UKRAINIAN MEDICAL STOMATOLOGICAL ACADEMY
Yeroshenko G.A., Klepets O.V., Perederii N.O., Vatsenko A.V., Ulanovska-Tsyba N.A., Riabushko O.B., Shevchenko K.V.
Biological features
of the human vital activity
Training text-book
on Medical biology (module I)
for students of medical and stomatological faculties
Poltava – 2021
Composite authors:
Yeroshenko G.A., Klepets O.V., Perederii N.O., Vatsenko A.V., Ulanovska-Tsyba N.A., Riabushko O.B., Shevchenko K.V.
Reviewers:
L.Ya. Fedoniuk – the head of the Medical Biology department of the Ternopil National Medical University, doctor of biological sciences, professor.
L.Ye. Kovalchuk – the head of the Medical Biology and Medical Genetics department of Ivano Frankivsk National Medical University, doctor of medical sciences, professor.
S.M. Bilash – the head of the Clinical Anatomy and Operative Surgery Department of Ukrainian Medical Stomatological Academy, doctor of biological sciences, professor
O.M. Bieliaieva – the head of the Foreign Languages with Latin and Medical Terminology Department of Ukrainian Medical Stomatological Academy, candidate of pedagogical sciences, associate professor.
Recommended by the Academic Board of the Ukrainian Medical Stomatological Academy as a training text-book for English-speaking students in speciality 221 Dentistry and 222 Medicine in a higher educational institutions of the Ministry of Health of Ukraine (dated 10.03.2021, minutes of the meeting № 7).
B 60 Biological features of the human vital activity. Training text-book on Medical biology (module I) for students of medical and stomatological faculties / G.A. Yeroshenko, O.V. Klepets, N.O. Perederii et al. – Poltava, 2021. – 82 p.
ISBN 978-617-7464-73-9
Textbook for students of the internatonal faculty of training foreign students in the specialty 222 – Medicine, 221 – Dentistry
Training text-book includes the tests of the 1st level (with one right answer), tests of the 2nd level – with the numerous choice of answers, typical tasks, in accordance with the Program of Medical biology for the students of medical and stomatological faculties of Higher Medical Educational Establishments of III–IV levels of accreditation, and also materials for self- preparation work.
Text-book will help students to master theoretical knowledge during audience classes and self-dependent preparation to the module control.
Methodical edition includes tests from the base of previous years tests of licensed examination «Krok-1» and tests which worked out by teachers of Medical biology departments that will help students to prepare effectively and pass module control as well as licensed examination.
UDC 577:61 (075.8)
The test tasks highlighted by the frame are taken from the «Krok-1» database.
TOPIC: Introduction to the course of medical biology.
Levels of living matter organization. Optical systems in biological research
Medical biology as a science about human vital activity. The essence of life. Forms of life, its fundamental properties and traits. Structural levels of life organization as a result of evolution. Importance of ideas about the levels of living for medicine. Optical systems in biological research. Structure of the light microscope. Making of temporary micropreparations, studying and description.
Medical biology as a science about human vital activity
Biology (from greek bios – life, logos – science) – the science about life and the general regularities of existence and development of living organisms: life processes, interaction with the environment, origin, historical and individual development of all living organisms. The theoretical foundation of biology based on Darwin's theory of evolution, cell theory of Teodor Schwann (1838) and Matias Schleiden (1839), Rudolf Virchow who has introduced the cell theory in medicine and other discoveries.
Modern biology is a complex of fundamental researches of wildlife in different levels. At the present moment of development biology could solve many biomedical problems, to penetrate into cells structure, its molecular organization and to get new understanding of the processes inside the cell.
Medical biology is the science about processes and mechanisms that occur in the human body, reguliarity of human cellular and tissue structure, individual human development, evolutionary and adaptive processes in human populations, adaptation to environmental conditions and influence of teratogenic and mutagenic factors, parasitic diseases, that exist in different human populations, and methods of their prevention and diagnosis, also many other theoretical and practical problems of a man. One of the major tasks of medical biology ‒ the study of human heredity, genotype of inherited diseases, genetic heterogeneity and individual genotypes and morphological differences of people, their environmental adaptability, development of boundary conditions, physiological characteristics and behavior.
Levels of living matter organization
Levels of life (levels of living matter) are structural organization of biosystems, reflecting their hierarchy depending on the degree of difficulty. There are basic structural levels:
Microsystems:
1. Molecular-genetic (fundamental) (size ≤ 1 nm):
elementary unit ‒ gene;
elementary processes ‒ replication and other processes of matrix synthesis, gene mutation.
2. Subcellular (size: 1–100 nm).
3. Cell (fundamental) (size: 0.2–20 microns).
Mesosystems:
4.Tissue (sizes: 10–100 microns).
5.Organ (sizes: ≥ 0.1 mm).
6.Organismic (or ontogenetic) (fundamental) (size: few mm – few dozens m).
Macrosystems:
7. Population-species (fundamental).
8. Biogeocenotic (or ecosystem).
9. Biosphere (global).
Basic properties of organisms
Questions about the human nature have been interested humanity throughout its development, but the final answer is not ready yet. Most scientists believe that life is a special form of existence of matter that differs from non-alive nature by features of the structure and functioning which in biology is called vital activity.
Living organisms ‒ complete biological system capable of self-regulation, self-renewal and self- reproduction (the fundamental properties of living). In their chemical composition is dominated by organic compounds: proteins, lipids, carbohydrates, nucleic acids, etc. They are forming by four chemical elements:
carbon, hydrogen, oxygen and nitrogen. Time of existence of organic compounds is limited. That is why biological systems are constantly changing and forming new ones.
Each biological system is capable to self-regulation ‒ it means regulation of their vital functions and maintaining their internal medium. That is why all living organisms are able to adapt for changes in the environment and respond for changes by intensity of their vital processes.
The necessary condition for existence of living beings is metabolism. As an open system living organism receives all necessary product from environment giving back the waste products of their metabolism.
Metabolism is closely associated with the transformation of energy: during the formation of complex compounds the energy expended but their cleavage is released. Functioning of any living organisms is impossible without wasting of energy so one of the most important process is a constant flow of energy from the environment. Only green plants and some prokaryotes and protozoans are capable of photosynthesis, absorbing light energy. Most organisms obtain the energy by means of food.
An important property of living organisms is ability for reproduction. Life of an individual organism as biological system is limited by particular term so existence of each species is provided by total reproduction of individuals.
The fundamental properties of living organisms
Self-regulation Self-renewal Self-reproduction
1. Exchange of substances and energy
3. Flow of energy and information
2. Reproduction on all levels
Living organisms biosystem as open self-regulated system
М1–М2 – metabolism; Е1–Е2 – exchange of energy; І1–І2 – exchange of information.
Optical systems in biological research. Structure of the light microscope During performing of biological research are using well-known as well as specific methods:
the method of observation;
method of biological experiment;
historical method;
descriptive method;
microscopic method;
X-ray analysis;
stepped centrifugation;
electron microscopy;
scanning electron microscopy;
electron microscope of histochemistry;
microspectral analysis;
statistical methods.
M1 М 2
E1 E2
І1 І2
The optical microscope, often referred to as light microscope, is an optical device for obtaining magnifications of very small objects, with using of visible light and a system of lenses.
Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although there are many complex designs which aim to improve resolution and sample contrast.
Every optical microscope consists of mechanical, optical and lighting systems.
The mechanical part of microscope includes:
– base (for supporting the microscope);
– arm (for retention of tube);
– tube (for retention of ocular);
– stage, or subject table (for placing the specimen);
– revolver (for shifting and retention of the objectives) – screw of stage moving;
– macroscrew (for moving a tube);
– microscrew (for adjustment of image clarity);
– screw of condenser.
The optical part of microscope consists of:
– ocular, or eyepiece (placed in the upper tube part;
the increasing degree can be x7, x10, x15);
– objectives (provide a different magnification, containing the lens of small increasing (x8), the lens of large
increasing (x40) and the immerse (x90) lens);
– aperture of stage (for passing light to the specimen).
To the light part of microscope are included:
– condenser (a system of lenses (mirrors) that collects and directs rays from a light source to the studied object);
– diaphragm (limiting beams of light rays);
– mirror (directs the flow of light; it has two surfaces – the plate and the concave one: to have the intensive lighting at the condenser lacking they use the concave glass surface; while working with immerse lens one can
use the condenser and the flat glass).
Consideration of any specimen begins at a small increase, which examines the general plan of its structure. In-depth study of structural components is provided on a large increase of the microscope.
Remember! The total increasing of microscope is equal to the ocular increasing multiplied by the lens increasing (e.g. the eyepiece 7 x the lens 8 = 40 times).
The microscope gives an increased and reversed imaging of the object!
The structure of light microscope: 1 – base; 2 – arm;
3 – tube; 4 – stage; 5 – aperture of stage; 6 – screw of stage moving; 7 – ocular; 8 – revolver; 9 – objectives;
10 – macroscrew; 11 – microscrew; 12 – condenser;
13 – screw of condenser; 14 – diaphragm, 15 – mirror.
The rules for work with microscope:
1. Set the microscope with the stand towards you and the subject table opposite you.
2. Put in the working state the lens of a small increasing. For this purpose rotate the revolving nosepiece till the required lens occupies the middle place in comparison with the tube and the subject table. When the lens occupies the middle place the light click is heard and the lens is fixed. Remember that the learning of any object begins with a small increasing!
3. By means of a coarse adjustment pick up the lens above the subject table up to altitude of about 0.5 cm.
4. Looking through the eyepiece with your left eye rotate the glass in various directions until the vision field will be lit up brightly and evenly.
5. Put the preparation on the subject table so that the object would be in the center of the subject table opening.
6. Further, under the eyesight control slowly lower the draw tube by the coarse of adjustment so the lens to be found at the distance of 2 mm from the preparation.
7. Look through the eyepiece and simultaneously slowly pick the tube up until the object picture appears in the field of vision.
8. To come to the object vision at the large microscope increasing first of all it’s necessary to place the object in the center of the vision field. If the object isn’t centered so at a large increasing it may stay out of the vision field.
9. Moving the revolving nosepiece put the lenses of large increasing in working state.
10. Lower the tube under the eye control (see how the tube is lowering not into the eyepiece but from one side) nearly to the contact with the preparation.
11.Then looking through the eyepiece slowly (!) to pick the tube up till the object picture is in the vision field.
12.To have the careful focusing use the fine adjustment.
13.When studying the smallest objects in light microscope they use immerse (from Latin immersion – to plunge into) lens. While working with this lens it’s necessary to drop the special substance on the cover glass. This substance has the similar refraction index with the glass. Normally to gain this goal they use the cedar oil.
There is no air layer between the lens and the covering glass. That’s why the light ray passes through the homogeneous with regard to the refraction index without any refraction.
14.Lower the tube (looking at it from one side) so that the lower lens would plunge into the immerse oil drop.
15.Then looking through the lens by means only of the fine adjustment you should lower and then raise the lens carefully to receive the exact vision.
Remember! The work with the optical microscope requires more careful attention!
1st level tests
(one correct answer)
1. One of the basic properties of living organisms isability for reproduction. What of the following level of organization of living organisms is carried out of this process on the basis of matrix synthesis?
A. Organismic B. Subcellular C. Cellular D. Tissue E. Molecular.
2. Existence of life on all levels is determined the structure of lower level. What level of organization existence of life is preceded and provides on cellular level:
A. Molecular B. Tissue C. Organismic
D. Population-species E. Biocenotic.
3. To the light part of microscope belong:
A. Mirror B. Revolver C. Base
D. Arm E. Ocular.
4. To the optical part of microscope belong:
A. Objective
B. Micrometer screw C. Mirror
D. Base
E. Macrometer screw.
5. To the mechanical part of microscope belong:
A. Tube B. Condensor C. Ocular D. Mirror E. Objective.
6. Immersion is used for increasing:
A. х 7 B. х 10 C. х 40 D. х 20 E. х 90.
7. Which process takes place during lowering of condenser of light microscope:
A. Illumination of the specimen diminishes B. Illumination of the specimen increases C. Focus is changed
D. The image of object becomes more clear E. The contrasty of image of object diminishes.
8. What function of micrometer screw:
A. Exact focus of object's image
B. Diminishing of the object
C. Improvement of light of the object D. Focusing of image
E. Increasing of image.
9. Part of the field of vision is lighted up well and part is black if:
A. Dirty lenses of objective B. Dirty lenses of ocular C. Dirty glass
D. Objective did not occupy the fixed position in the revolver disk
E. Dirty covering glass.
10. Image of object on a microslide isvisible on small icreasing but does not on large increasing of microscope because:
A. Dirty covering glass
B. Covering glass lies under the microslide C. Dirty lenses of ocular
D. Objective is out of plane of image focus E. Insufficient light of object.
11. Define property of life which provides heredity between parents and descendants:
A. Self-regeneration B. Self-regulation C. Self-reproduction D. Development E. Growth.
12. What factors conditioned appearance of independent systematic unit of Homo sapiens in the process of evolution?
A. Social B. Biological C. Anthropogenic D. Physical E. Chemical.
13. Choose the wrong answer:
A. Organism is the opened biological system B. Multicellular organism is not simply sum of
cells in the «cellular state»
C. Organism is a self-regulated system D. Organism is not self-regulated system
E. Organism is opened self-regenerative and self-reproductive system.
14. Choose the correct answer:
A. Cell is an elementary unit of structure and development of organisms
B. Cell is able to development
C. Cell is an elementary opened biological system which is able to the self-regeneration and development
D. Cell is an elementary opened biological system which is able to the self-regeneration and self-regulation
E. Cell is an elementary opened biological system which is able to the self-regeneration.
15. What level of organization is fundamental and determines the typical metabolism?
A. Organismic B. Subcellular C. Cellular
D. TissueMolecular-genetic.
16. Chromosome of prokatyotes is a circular DNA molecule. Name the level of organization of hereditary material:
A. Chromosomal B. Microfibre
C. Molecular-genetic D. Nucleosome E. Tissue.
17. One of fundamental level is organismic. On this level genotype is determined by ontogenesis of organism,
its phenotype, adaptation and behavior in the environment. What ecological problems do arise up for a man on this level?
A. Increase of amount of population B. Development of border states C. Increase of agriculture cenosis D. Pollution of environment E. Destruction of ozone layer.
18. Organisms which do not have membranous organelles and their genetic material does not have nucleosome organization belong to the group:
A. Fungi B. Viruses C. Eykaryotes D. Prokaryotes E. Protozoa.
19. Living matter is characterized by evolutionally conditioned structural levels of organization. On which of these levels the genotype determines the typical for an organism metabolism and energy:
A. Molecular-genetics B. Organs
C. Organismic D. Cellular E. Tissue.
20. Metabolism, changing of an energy and information are necessary for the existence of living biological systems. Which ensuring universal substance provides needs of metabolic energy?
A. Adenosine triphosphate B. Dioxyadenyltriphosphate C. Glucose
D. Creatine phosphate E. Acetyl-CoA.
21. Wildlife is characterized by the evolutional conditioned structural levels of the organization. What level is the genoplast as a control system?
A. Molecular-genetic B. Organism
C. Biogeocenotic D. Tissue
E. Overmolecular.
22. What forms of life exhibit their properties only at the stage of intracellular parasitism?
A. Bacteria B. Bacteriophages C. Cyanea
D. Parasitic fungi E. Salmonella.
23. Cell as an open biological system is characterized by metabolism, energy and information. What mitochondrial formation process provides the maximum amount of energy during respiration?
A. Krebs cycle B. Glycolysis
C. Transport H+ channel by ATP synthase D. Moving of electrons in electron transport
chain
E. Photorespiration.
24. Each biological system is capable of self-regulation:
the regulation of their vital functions, maintaining of
homeostasis. What is important property defines self- regulation?
A. Energy conversion
B. Update of molecular composition C. Adapting to environmental changes D. Reproductions of biosystems E. Synthesis of nucleic acids.
25. Attribute of life is the preservation and transmission of information flow. What process provides information safety on the molecular genetic level?
A. Mitosis
B. Sexual reproduction C. Transcription D. Gene expression E. Replication.
26. Each biological system adapts to the environmental changes and defines changes in their life functions and homeostasis maintaining. What is the fundamental property of living systems which determines the ability to adapt to the different environmental conditions?
A. Self-renewal B. Self-regulation C. Metabolism D. Self-renewal E. Reproduction.
27. What is the name of the genotypes and phenotypes adapted to each other in their environmental populations?
A. Biogeocenosis B. Genoplast C. Anthropocenosis D. Population E. Isolation.
28. On which levels do environmental problems appear such as growth of mutagenic effects and mutational increase in their genofund?
A. Organism B. Subcellular C. Cellular D. Tissue
E. Molecular-genetiс.
2nd level tests
(few correct answers)
1. Name the level of organization of the livingsystems on which a genotype is determined by the typical cellular metabolism:
A. Molecular-genetics:
B. Organismic C. Cellular
D. Population-species E. Subcellular
F. Biosphere.
2. Name the fundamental level of life organization:
A. Ontogenetics B. Subcellular C. Cellular
D. Molecular-genetics E. Population-species.
3. Name the level of life organization where genotype determines ontogenesis:
A. Population-species B. Molecular-genetics C. Cellular
D. Organismic E. Subcellular F. Biosphere.
4. Fundamental properties of a cell as a open biosystem are:
A. Self-correction B. Self-regulation C. Self-reproduction D. Self-providing.
5. Cell or an organism have such properties as an open alive system:
A. Metabolism B. Variation C. Ontogenesis D. Discrete unit.
TOPIC: Cell morphophysiology. Structural components of cytoplasm
Structural-functional organization of eukaryotic cells. Chemical composition of cells: macro- and microelements. Water, importance of hydrogen bonds in the processes of cellular activity. Organic compounds ‒ carbon-containing substances of living organisms. Cytoplasm and cytoskeleton. Cyclosis.
Cytoplasmic organelles ‒ membranous and non-membranous, importance and principles of functioning.
Inclusion of cells, their function. Methods of studying of structure and functioning of cells.
Cell theory. The study of cellular activity is one of the necessary steps in understanding of pathological processes that students continue to study on the pathological anatomy and physiology departments, inner and surgical diseases and also on other departments where the diseases studied on organisms, systems and tissue- organ levels.
Cell theory was established in 1838–1839 (T. Schwann, M. Schleiden). The main statements of the cell theory have retained their value to the present time, but nowadays were obtained new data about structure and vital functions of cells.
The modern cell theory includes such statments:
Cell is an elementary structural-functional and genetic unit of life.
Cells of different organisms homologous by their structure.
Cell division occurs by dividing of an initial mother cell.
Multicellular organisms are complexes of various cells and their derivatives which are incorporated in the whole integrated system of tissues, organs and united among themselves by intercellular, humoral and nervous forms of regulation.
Cell is the smallest structure of life, which has all characteristics and properties of life.
The concept of cell as the smallest unit of life proved by T. Schwann and R. Virchow who believed that every cell is characterized by all attributes of living things.
According to the modern data, all living organisms are opened self-regulated systems where important components are nucleic acids and proteins.
DNA codes information about the structure of proteins, but protein are complexes of molecules which have functional specificity and determine realization of genetic information and properties of life: ability to self-reproduction and self-regulation, ensure the flow of matter and energy during metabolism, heredity and variability, sensitivity, movement, adaptation. Such properties firstly defined on the cellular level that is why cells are elementary structural and functional units of life.
The cell.
Non-cellular and cellular forms of life
Throughout the organic world can be divided into two life forms: cellular and non-cellular.
Non-cellular forms of life – viruses – are forming the kingdom of Vira which is divided by the type of nucleic acids on riboviruses and deoxyviruses. Viruses of human and vertebrates include 17 families where 6 of them are DNA-containing (DNA genomic) and 11 ones are RNA-containing (RNA genomic).
Viruses are form of life that exhibit the properties of living cells and only parasitizing in pro- and eukaryotes. Viruses are microscopic in size but vary in wide limits: from 15–18 nm to 300–400 nm and have different shapes: bacilli-shaped, spherical, spermatozoid-shaped et al.
Viruses differ from pro- and eukaryotes by structural organization and functional features. They contain only one of the nucleic acids ‒ DNA or RNA and have non-cellular structure. Viruses are not capable of growth and binary fission. Viruses are formed acquiring certain shape and exact size that do not change. Reproduction of virus is cell replicating by means of nucleic acids. In the virus there are no an autonomous process of metabolism
and own systems of energy storage and protein synthesis, they use enzyme systems, energy sources of living cells, turn the work of cells to produce new viral particles.
Viruses exist in two forms: extracellular – virion and intracellular ‒ a virus. According to the structure virions are divided into simple and complex. Simple virions consist of NA and protein. NA is covered with outer protein envelope – capsid, which protect viral genome from external environment. NA and protein form together nucleocapsid.
Complex virions have NA, protein, lipids, carbohydrates and enzymes. Lipids, carbohydrates and proteins make up the outer membrane called supercapsid.
The molecular weight of viral DNA is 10–100 times less than the molecular weight of bacterial DNA. The genome contains up to several hundred genes. DNA can be single and double-stranded, they are capable of being locked in the ring and replicated in this form, transcribed, acquired resistance to endonuclease enzymes, and incorporate into the cell genome.
Viral RNA are similar to the RNA of cells but can be one-stranded and double-stranded. One-stranded RNA depending on the functions are divided into 2 groups. Some of them are able to perform the function of iRNA (positive genom), others may be a matrix for the formation of iRNA during reverse transcription (negative genom).
Viruses, which parasite in bacterial cells, are called bacteriophages. They have a more complex structure than most viruses. The bacteriophage consists of the head and the appendage. The head contains nucleic acid.
The capsid of the head has a cubic structure, and the appendage is spiral. Penetrating to the bacterial cell, the phages inject the nucleic acid through the canal of appendage. In a bacterial cell, phage's nucleic acid is intensively multiplied, causing its lysis. Sometimes the penetration of phages into a bacterial cell is not accompanied by its lysis, and the phage's DNA is embedded in the bacterial genome and transmitted to its descendants.
Viruses have a great importance, the most of them cause diseases of plants, animals and humans. In human viral diseases are: smallpox, taiga encephalitis, measles, influenza, AIDS and others. In addition, viruses can provide transfer of genetic material (transduction).
Cellular life forms, depending on presence of formed nucleus, divided into prokaryotes and eukaryotes.
Prokaryotes – organisms whose cells have no nucleus. Eukaryotes – organisms whose cells have one or more nuclei. Prokaryotes include representatives of bacteria and blue-green algae.
The cells of prokaryotes are small in size (0.1–0.25 mcm – mycoplasma; 1.10 mcm – bacteria, blue-green algae). Prokaryotes cells have a cell membrane, cytoplasm. The membrane is represented by the complex structure of the cell wall and cytoplasmic membrane. On the surface the mucous capsule can be formed. In the cytoplasm are organelles: ribosomes and membrane formation ‒ mezosome, photosynthetic membranes, etc.
In the middle zone of prokariotic cel it can be founded nucleoid (localization of hereditary material) where the bacterial chromosome ‒ circular molecule of DNA which is not connected with protein histones ‒ localized.
Prokaryotic cell hasn’t typical membranous organelles. There are no centrioles, the system of microtubules and microfilaments is poorly developed. Prokaryotes cells have an intensive metabolism, often occurring mutations and faster processes of adaptation to the environment. Cell reproduction is binary fission with doubling of DNA molecule.
Comparison of prokaryotes and eukaryotes
Cell structure Prokaryotes Eukaryotes
Cell membrane +
+
Nucleus
–
+Hereditary material Circular DNA Linear chromosome,
DNA-histone, proteins
ER
–
+Ribosome Smaller in size Larger in size
Golgi complex
–
+Lysosome
–
+Mitochondrion
–
+Mesosome +
–
Eukaryotes include representatives of three kingdoms: Plants, Fungi, Animals. Their cells have a nucleus, membrane organelles (ER, Golgi complex, lysosomes) and developed non-membranous organelles (ribosomes, microtubules and microfilaments system, centrioles). Hereditary material presented by linear chromosomes that include DNA, histones, acidic proteins. The main way of division is mitosis ‒ complex of evolutionary process which provides transmission and distribution of hereditary material.
Structural and functional organization of eukaryotic cells
Eukaryotic cells are constructed of three main components: membrane, cytoplasm and nucleus. There are two subtypes of cell: cells of unicellular organisms which are also individual organisms and cells of multicellular organisms (plants, animals, fungi).
Particular importance in cellular organization belongs to biological membranes (biomembranes) which form: cell membrane (plasmalemma), membrane of nucleus and membrane of mitochondria and plastids, membranous organelles (endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, vacuoles).
Membranes are complex molecular systems, liquid-crystalline solutions of globular proteins in lipid biostructures which define the basic life processes at the cellular level.
Cell membrane.
Organelles of cytoplasm. Cells of multicellular organisms separated by cell membrane, which formed a membrane covered by the layer outside (thickness 10‒20 nm). Inside the membrane the cortical layer of cytoplasm has attached where the large number of microfilaments and microtubules are formed by the contractile proteins. Cells filled by cytoplasm where the nucleus localized.
Cytoplasm (cytosol + cytoskeleton + organelles + inclusion). Chemical content:
Water (≥ 75%);
Salt (1–2%);
Gases (CO2, O2, N2, NH4+);
Organic matter (20–25%) – about 10,000 different proteins, fats, carbohydrates, NA.
Functions of cytoplasm:
- environment for biochemical reactions;
- support structure of organells;
- the growth and differentiation of cells;
- restoration of molecules structures;
- reservoir for different substrates;
- ensure constancy of the concentration of substances which are necessary for the existence of cells (homeostasis);
- transformation of damaged materials.
The cytoplasm is the main mass of a cell, its internal content, except the nucleus. It contains 75‒85%
water, 15-25% protein and many other substances. Cytoplasm is homogeneous, colorless, transparent with viscous liquid. Cytoplasm is a multicomponent, multifunctional complex. The cytoplasm contains the cytosol (cytoplasmic matrix), organelles and inclusions.
Cytosol (or hyaloplasm) is 55% of total cells mass. This colloid formed by mix complex of macromolecules:
fats, carbohydrates and non-organic substances (more than 10,000 different proteins).
In the cytosol there are non-organic (water, salts, gases) and organic substances. Water is the main part of cytosol (75%). Salts are 1‒2% cytosol, they form ions. Mostly they are carbonates, bicarbonates, phosphates, sulfates and chlorides of sodium, potassium, calcium, magnesium and iron. They determine the osmotic properties of cytosol. Many of them are involved in biological processes. Cells has oxygen, carbon, nitrogen and ammonia. CO2 is a result of metabolism, the final product of oxidation reactions and permanently removed from cells.
Organic substances constitute 20‒25% of living cells mass. The main groups of these substances are:
proteins, fats, carbohydrates and nucleic acids. They define the structure and function of cells (energy substrates oxidation and so on).
Functions of cell organelles provides by continuous, necessary for them surroundings of cytosol. From the cytosol organelles receive the necessary materials and involved to the maintenance of cell homeostasis.
Chemical reactions occurring in the cytosol provide constancy of a cell and its structural organization. In the cytosol constantly maintained concentration of water, gas, substances for chemical reactions, pH. These conditions are necessary for the flow of biochemical and physiological processes. Due to continuous synthesis of molecules all damaged molecules are exchanged by new synthesized molecules.
Cytoskeleton is a network of protein filaments and microtubules which covered inside by cytoplasmic membrane and goes through the internal space of a cell. Cytoskeleton consists of three types of structures:
1) microtubules (formed by several proteins fibrils containing globular protein – tubulin; 2) microfilaments (the thinnest) which formed by globular proteins – actin; 3) intermediate filaments (several microfilaments combination).
Functions of cytoskeleton:
1. Determination of volume and shape of cells and their changes. The main role has fibrillar net – cortex that covers membrane inside. Microfilaments and microtubules are connected to the net which greatly stabilizes the shape of cells. The system of protein filaments is able for contraction and tension which leads to the change of shape.
2. Movement of organelles and their transport. Cytoskeleton filaments attached to the cell organelles. This is stabilizing of their position in cytoplasm. Changing the length of fibrils leads to movement of cellular structures.
3. Forming of compartments of cytoplasm. Binding of several cytoskeleton filaments created favorable conditions for the placement of complex enzymatic proteins. It provides structural union of enzymes for specific metabolic processes.
4. Integration of all cytoplasm to the organic whole.
5. Formation of spindle during mitosis and specific organelles (villi and flagella). Providing contractile function of muscle fibers.
6. Formation of contacts between cells (desmosomes).
Cytoplasm is heterogeneous in its structure. Membrane components of cytoplasm are closed zones (compartments) which specialized to perform certain functions. Content of separated or interconnected compartments is isolated by membranes from hyaloplasm and plasmallema.
Membrane structures of cytoplasm can be divided into several groups:
1) One-membranous organelles are vacuole, endoplasmic reticulum (ER), Golgi complex, lysosomes, peroxisome.
2) Two-membranous organelles ‒ mitochondria and plastids. They have an outer and inner membranes, which do not pass each other, opposite to nuclear membrane where the outer membrane can be connected with ER membranes.
3) Non-membranous organelles ‒ ribosomes, centrioles, microtubules, microfilaments, myofibrils, etc.
Tubular and vacuole system presented by tubular or flattened cavity (tank) and separated from the membrane of hyaloplasm and placed throughout the cytoplasm.
Endoplasmic reticulum.
There are many ribosomes on rough (or granular) ER because it synthesizes proteins, most of these proteins secreted from cells, for example, proteins that are secreted by cells of glands. Here also formed proteins and lipids of plasmalemma.
Tanks can form tightly packed layer structure ‒ the most active sites of protein synthesis, called ergoplasm.
Agranular (or smooth) ER does not have ribosomes. It takes part in an exchange of fats, carbohydrates, steroid hormones and other substances. In the tubules there are accumulation and transport of substances from sites of synthesis to zone of formation of granules. In the cells of various organs ER can perform specific functions. For example, in liver cells with developed smooth ER toxic substances and some drugs are destroyed. In tubes of smooth ER in muscle cells ions Ca2+, required for the constriction process, are deposited.
Golgi complex formed by dictyosome (from several to thousands per cell). Dictyosome formed from 3–12 flat discoid cisterns, the edges are separated by blisters (vesicles).
Some areas – expansion of tank form larger vesicles (vacuoles). Golgi complex forms secretory vesicles and vacuoles containing proteins and other compounds secreted by cells.
Preceded secretion (prosecret) comes to the dictyosome from synthesis zone, there some chemical modification occurs, and then the secret is separated into portions membrane (segregation). Golgi complex forms lysosomes and also synthesizes polysaccharides, glycoproteins, glycolipids.
System of cytoplasmic structures is a single entity and some individual elements can pass through each other. Thus the outer membrane of nuclear envelope membrane becomes granular ER, etc.
Mitochondria – two-membranous semi-autonomous organelles of all eukaryotic cells, round or oval- shaped; dimensions: thickness 0.5 mm, length 5–10 microns for the most cells.
Matrix. In the matrix there are grains (diameter 20‒40 nm), which accumulate Ca2+ and Mg2+, and polysaccharides (glycogen), 2‒6 copies of circular DNA molecules (proteins without histones), ribosomes, tRNA, enzymes of DNA replication, transcription and translation.
According to the size and structure of ribosomes, DNA organization of this organelle is similar to prokaryotes mitochondrion. Mitochondrial DNA genes of synthesis include the mitochondrial rRNA, tRNA and inner proteins. Most mitochondrial proteins encoded in nuclear DNA and are formed in the cytoplasm.
Lysosomes – one-membranous organelles, which sometimes are covered outside with a layer of fibrous protein.
Lysosomes divided into four types: primary lysosomes, secondary lysosomes, residual cells and autophagous.
Primary lysosomes are small membranous structures, 100 nm in diameter, filled with enzymes in an inactive state.
Secondary lysosomes formed from the merger of primary endocytosis of vacuoles. Processes of digestion of substances that come during endocytosis take place by means of hydrolytic enzymes.
Secondary lysosomes are divided into heterolysosomes and autolysosomes.
Microbodies are group of membranous organelles, vesicles, diameter is about 0.1‒1.5 mcm with grained matrix and protein inclusions. These organelles include, for instance, peroxisome. They contain enzymes oxidase, which catalyze the deamination of amino acids and the formation of hydrogen peroxide (H2O2). Hydrogen peroxide is a toxic product, it can be destroyed by enzyme peroxidase (catalase).
Peroxisomes are bounded by ER membrane and formed on extended sections of tanks. In animals and some plants peroxisomes take part in the splitting of fats and carbohydrates.
Vacuoles are membrane organelles of plant cells that perform important functions. In the young cells they are small, then grow and merge forming one or more large vacuoles, occupying up to 80% of the cytoplasm.
Functions:
maintaining turgor pressure;
osmoregulation;
accumulation of substances excreted by cells;
accumulation of reserve substances (proteins, monosaccharides, inulin);
accumulation of enzymes which digest nutrients during germination of seeds.
Ribosomes are small round bodies with diameter of 20‒30 mm, located on hyaloplasm membranes and granular ER.
Ribosomes consist of small and large subunits, the association occurs in the presence of informational RNA. Each subunit is located on the molecule of rRNA and proteins.
Ribosomes which are combined with iRNA resemble a series of necklaces and this structure called polysomes. Free polysomes are located in cytoplasm or attached to membranes of granular ER. The proteins that are used for own needs of cell are synthesized in polysomes of hyaloplasm, but proteins which cells secret (digestive enzymes, saliva mucin and others) are synthesized on polysomes of granular ER.
Centrioles are non-membranous organelles, according to the electron microscope have the appearance of hollow cylinder (width 0.15 mcm, length 0.3‒0.5 mcm). The walls of cylinder is formed by 27 microtubules, grouped in 9 triplets. Near the centrioles there are satellites of microtubules, fibrous roots, additional microtubules, which form a special zone ‒ centrosphere. Centrioles (2‒3) and centrosphere form the cell center.
Cell center changes its structure during the cell cycle. For example, from prophase to telophase centrioles have similar structure, but during mitosis two cell center are formed with two centrioles.
At the end of telophase when despiralization of chromosomes occurs and interphase nuclei formed new one, maternal spindle division is destroyed and daughter centrioles move to the small distance and lose their previous perpendicular placement. In G1 (G0) during interphase cell center is formed by 3 centrioles. The functions of centrioles ‒ formation of division apparatus during mitosis, providing movement of chromatids (chromosomes) in anaphase (mitosis), organization of cytoplasmic microtubules (cytoskeleton) during interphase. Centrioles are characteristic of animal cells, they are absent in higher plants, fungi and some Protozoa. Threads of mitotic spindle consists of microtubules. When cell division centrioles diverge in opposite directions and form the poles of the cell they provide moving apart of sisters’ chromatids (chromosomes) in anaphase (mitosis).
Cytoplasm of eukaryotic cells contains two types of structural elements of non-membranous nature ‒ microtubules and microfilaments.
Microtubules are tubular formation of different lengths (24 nm diameter, wall thickness is 5 nm). Located in the free state in cytoplasm of cells they are structural elements of cilia, flagella, mitotic spindle threads, centrioles. Microtubules are formed from subunits of proteins by their polymerization (in the presence of Mg2+).
In cytoplasm free tubes perform controversial feature, determine the shape of cells and directed movement of cytoplasmic components.
Microfilaments – long and thin structure of the cytoplasm (thickness is 7 nm) which can form bundles.
Especially many of them located in the cortical layer of cytoplasm. There are actin microfilaments (contain contractile proteins ‒ actin), which provide cellular forms of movement, for example, ameboid type. They serve as the frame function and determine the movement of intracellular organelles and hyaloplasm.
Under plasmalemma and in space around the nuleus there are thick bundles of microfilaments (about 10 nm) ‒ intermediate microfilaments. In different types of cells they are constructed from different proteins.
The system of intermediate microfilaments is also dynamically moving as well as systems of microtubules and actin filaments. In dividing cells, they break up into two horseshoe-shaped structures after formation of daughter cells surrounding by nucleus again. Therefore, their main function is mechanical. This proves the fact, that in many epithelial cells, especially integumentary epithelium, intermediate microfilaments form thick bundles of monofibrills that help for cells to be more elastic.
1st level tests (one correct answer) 1. A 36-year-old patient underwent tooth extraction at
a dental clinic. After two weeks the stratified squamous epithelium regenerated at the site of extraction. What organelles were involved in the restoration of the mucous membrane?
A. Centrosomes B. Mitochondria
C. Smooth endoplasmic reticulum D. Ribosomes
E. Lysosomes.
2. During histologic examination of the skeletal muscle specimen, the investigator discovers an organelle that has 2 membranes: smooth outer membrane and internal, that forms multiple ridges of visible folds (crysts). Which of the following is the most likely function of this structure?
A. Formation of mitotic spindle B. Synthesis of carbohydrates
C. Synthesis and energy accumulation in the form of ATP
D. There is no correct answer
E. Intracellular digestion of macromolecules.
3. A patient with chronic hepatitis undergoes blood test for serum protein fractions. Total protein levels are low, which indicates that in the hepatic cells the following organelles are functionally disturbed:
A. Granular endoplasmic reticulum B. Mitochondria
C. Cytoskeleton D. Golgi apparatus E. Lysosomes.
4. Long-term taking of medicines can affect cells of the liver. Particularly, it can cause marked hypertrophy of agranular endoplasmic reticulum due to the following function of this organelle:
A. Nucleic acid synthesis
B. Protein synthesis
C. Formation of maturation spindle D. Detoxication of harmful substances E. Intracellular digestion.
5. Cells of a healthy liver actively synthesize glycogen and proteins. What organelles are the most developed in them?
A. Cell center B. Lysosomes C. Mitochondria D. Peroxisomes
E. Granular and agranular endoplasmic reticulum.
6. The organisms to be identified have a nucleus surrounded by a nuclear membrane. Genetic material is concentrated predominantly in the chromosomes that consist of DNA strands and protein molecules. These cells divide mitotically. Identify these organisms:
A. Bacteriophages B. Prokaryotes C. Eukaryotes D. Viruses E. Bacteria.
7. Cytochemical investigation revealed high content of hydrolytic enzymes in the cytoplasm. This phenomenon indicates the activity of the following organelles:
A. Lysosomes
B. Endoplasmic reticulum C. Mitochondria
D. Polysomes E. Cell center.
8. Human red blood cells contain no mitochondria.
What is the main pathway for ATP production in these cells?
A. Oxidative phosphorylation
B. Creatine kinase reaction C. Cyclase reaction D. Anaerobic glycolysis E. Aerobic glycolysis.
9. The cell of the laboratory animal was overdosed with Roentgen rays. As a result albuminous fragments formed in the cytoplasm. What cell organoid will take part at their utilization?
A. Golgi complex B. Ribosome
C. Endoplasmic reticulum D. Lysosomes
E. Cell centre.
10. In course of practical training students studied a stained blood smear of a mouse with bacteria phagocyted by leukocytes. What cell organella completes digestion of these bacteria?
A. Mytochondrions
B. Granular endoplasmic reticulum C. Golgi apparatus
D. Ribosomes E. Lisosomes.
11. There is an organelle in cell. The function is:
lysosome formation, polysaccharide synthesis, lipid synthesis and other. Name this organelle.
A. Lysosome B. ER
C. Complex Golgi D. Peroxisome E. Ribosome.
12. Child has a dyspepsia caused by dehydration of organism. What solution is needed to renew osmotic pressure of circulatory blood?
A. Isotonic solution NaCI B. Hypotonic solution C. Hypertensive solution D. Salt solution
E. 1% solution of glucose.
13. Glass-shaped cells inside the epithelium of mucous membrane of intestine and respiratory tracts excrete the glycoprotein mucin which forms mucus in solution. What organoid secretes the mucus?
A. ER B. Lysosome C. Golgi complex D. Ribosome E. Cell centre.
14. In the cells of frog experimentally destroyed the system of microtubules, located in a cytoplasm. Cells became sphere-shaped. What function of microtubules?
A. Modify products which are coming to the cell B. Forming of secondary protein structure C. Forming of cytoskeleton
D. Secretion of steroid hormones E. Detoxication of products.
15. The main function of hepatocyte is detoxication.
The organelle, which performs this function, is:
A. Mitochondria B. Centrosome C. Nucleus D. ER E. Ribosome.
16. Oval-shaped structure and two membranes with cristae has:
A. Lysosome B. Rybosome C. Mitochondria D. Centrosome E. ER.
17. In the cells of muscles tissue there is an intensive aerobic process of forming and accumulation of ATP energy. In what cell organoid do these processes take place?
A. Peroxisome B. ER
C. Lysosome D. Mitochondria E. Cell centre.
18. The virus of flu got into the cell. The mechanism of biosynthesis of protein reorganized abnormally and afterwards the synthesis of viral protein began to carried out:
A. On polyribosomes B. In nucleus
C. In lysosome D. In peroxisome E. In cell centre.
19. One-membranous organelle contains enzymes and provides intracellular digestion. Name this organelle.
A. ER
B. Centrosome C. Lysosome D. Ribosome E. Mitochondria.
20. The 40-years man has a wound after pulling out of tooth where the active process of regeneration takes place. Define the organelle performs this process immediately:
A. Ribosome B. Lysosome C. ER
D. Centrosome E. Mitochondria.
21. One-membranous circle-shaped organelle has a size 0.2–1 mcm and contains enzymes. The forming of this organelle connected with Golgi complex. Name this organelle:
A. Centrosome B. Ribosome C. Plastids D. Mitochondria E. Lysosome.
22. Circle-shaped organelle (one-membranous) with hydrolytic enzymes has a name:
A. Centrosome B. Lysosome C. ER
D. Complex Golgi E. Ribosome.
23. In one of organoids there are processes of protein construction and complexing of protein with carbonhydrates, fats take place. Name this organoid:
A. Golgi complex B. ER
C. Lysosome D. Ribosome E. Mitochondria.
24. What organic matters are synthesized on the membranes of granular ER?
A. Nucleic acids B. Protein C. Carbohydrate D. Lipids
E. ATP.
25. Which organelle completes digestion of bacteria:
A. Lysosome B. Mitochondria C. Granular ER D. Golgi complex
E. Ribosome.
26. In all kind of cells there are non-membranous organoids which consist of two different particles. They have microscopic sizes and take part in the process of protein synthesis. Name this organelle:
A. Ribosome B. Lysosome C. Complex Golgi D. Cell centre E. Mitochondria.
27. During the study of pancreas cells by an electronic microscope some organelle was found out which consists of plenty ductings, cisterns and connected with plasmalemma:
A. Centrosome B. Mitochondria C. ER
D. Lysosome E. Peroxisome.
28. Near the nucleus some organelle was found out which consists of two cylinders and formed microtubules and located perpendicularly. It determines that this organelle is a constituent of mitotical spindle of division in animal cells. The name of this organelle is:
A. Mitochondria B. Ribosome C. ER
D. Centrosome E. Lysosome.
29. There are inconstant structures in nucleus which disappear at the beginning of cell division and afterwards again appear. They contain protein, RNA and take part in forming of subunits of ribosomes. How are such structures called?
A. Nucleolus B. Nucleosome C. Polysome D. Microfilaments E. Microtubules.
30. Sick person has a pancreatytis. This disease can be reason of autolysis of pancreas caused by function of:
A. Lysosome B. Mitochondria C. Ribosome D. ER E. Microvilli.
31. In animal cell two-membranous organelle which has molecules of DNA and ribosome was found. What is the basic function of this organelle:
A. Synthesis of protein B. Synthesis of ATP
C. Transport and modification of protein D. Synthesis of cytoplasm protein E. Formation of ribosome.
32. Forming of subunits of ribosomes is broken experimentally (by the action of mutagene factors). What metabolic process will be destroyed?
A. Synthesis of ATP
B. Biosynthesis of carbohydrates C. Photosynthesis
D. Cell division
E. Synthesis of protein.
33. There are membranous organelles in eukaryotes cell, which appear in complex Golgi and have enzymes for destruction of H2O2. What function of this organelle?
A. Formation of ATP B. Synthesis of polypeptide
C. Breaking up of protein D. Synthesis of carbohydrates E. Oxidation of lipids.
34. Mitochondria is semiautonomous organelle, matrix has 2–6 own rings of DNA, ribosomes, RNA, enzymes of replication, transcription and translation.
Where the information about the primary structure of most mitochondria protein is coded?
A. DNA of cytoplasm
B. DNA of sexual chromosomes C. RNA of matrix
D. DNA of mitochondria E. DNA of chromosomes.
35. Two types of cells appeared in the process of evolution: prokaryotes and eukaryotes. Which kinds of organelles are peculiar to the both types:
A. Lysosome B. ER
C. Mitochondria D. Ribosome E. Golgi complex.
36. ER is represented by smooth and rough systems which are functionally different. Protein and lipid synthesis are taking place:
A. In Golgi complex B. In smooth ER C. In rough ER
D. In smooth and rough ER E. In ribosomes.
37. Animal cells are able to the active movement.
What structures provide such peculiarity:
A. Actin microfilaments B. Microtubules
C. Intermediate microfilaments
D. Cell centre and microtubules of spindle E. Myofibrils.
38. Cell come under ionizing radiation influence by means of deficite of vitamin E. As a result of this is increased output of enzyme hydrolases to the cytoplasm and complete destruction of intracellular structures. What organoids are richer of hydrolases and can be reason of autolysis?
A. Lysosome B. ER
C. Golgi complex D. Microtubules E. Mitochondria.
39. Ribosomes have 4 active centre, 3 in each subunits: M-centre (connection with mRNA), A-centre (aminoacids centre), P-centre (peptide centre), PTF-centre (peptidyltransferase centre). Define centre of formation of peptide bonds?
A. А-centre B. М-centre C. P-centre D. PTF-centre E. P- + А-centre.
40. Detoxification of harmful matters takes place in hepatocytes which come with the blood to the liver. What organoid provides detoxication of matters in hepatocytes:
A. Rough ER B. Peroxisome C. Mitochondria D. Lysosome E. Golgi complex.
2nd level tests
(several correct answers)
1. Choose structures and substances of ribosomes:A. DNA+protein B. rRNA+protein
C. small subunit + big subunit
D. small subunit + big subunit+mRNA E. Phosphoric acid.
2. DNA is located:
A. In nucleus
B. In mitohondria and plastids C. In vacuoles
D. In ribosome E. In cytoplasm F. In cell centre G. In chromosomes.
3. Name membranous organoids:
A. Cell membrane B. Centriole C. Complex Golgi D. Ribosomes E. Lysosome F. Vacuole.
4. Lysosome provides:
A. Protein processing B. Secretion
C. Intracellular digestion D. Cyclosis
E. Accumulation of waste products.
5. Non-membranous organelles are:
A. Vacuoles B. Cell centre C. ER
D. Ribosome
E. Microtubules and microvilli F. Chromosomes
G. Flagela, cilia.
6. Two-membranous organelles are:
A. Mitochondria
B. Cell centre C. ER
D. Ribosome
E. Microvilli and microtubules F. Chloroplasts
G. Nucleus.
7. The man has a wound with pus. Which organelles provide process of healing?
A. Lysosome B. Golgi complex C. Ribosome D. Nucleus E. ER.
8. Preparation has taken on cell which caused destruction of mitochondria. What processes will be broken:
A. Lipid synthesis B. Glycolysis
C. Spindle formation D. Providing of energy E. Protein synthesis.
9. Preparation has taken on cell which caused destruction of cell centre. What processes will be broken? Which organelles will be formed?
A. Centrioles B. Protein synthesis
C. Mitosis and spindle formation D. Chromosomes will not move apart E. Microfilaments and microtubule.
10. What organelles of cytoplasm contain DNA?
A. Ribosomes B. Mitochondria C. Chromosomes D. Chromatin E. Peroxisome F. Chloroplasts.
TOPIC: Cell membrane. Transport through the plasmalemma
Cell as an open system. Assimilation and dissimilation. Cell membranes, their structure and function.
Principle of compartmentation. Receptors of cells. Transport of substances through the plasmalemma. Flows ofsubstances and energy. Stages of energy exchange. The energy of a cell, ATP. Distribution of energy.
Cell as an open system
A cell consists of many different arranged molecules. Molecular complexes formed organelles, which also have structure of cell systems. The interior part of cell biomembranes is divided into compartments where only specific reactions take place. Thus, the cell is a complex system of macromolecules at several levels of organization.
It is indivisible whole system in which you can identify a number of subsystems that are responsible for specific functions: membrane, cytosol, nucleus, mitochondria and others. Cellular organelles are structurally and functionally linked. Vital functions of cells may only be exercised in a coordinated connection between them.
A cell is an open system because it does not completely isolated from the environment. For life and functioning cells must constantly interact with the environment. In particular, between environment and cells the matter, energy and information are constantly exchange. These processes provided orderly in time and space, coordinated flow of metabolic and physiological processes.
The flow of substances associated primarily with cell metabolism, which is the unity of catabolism and anabolism.
Anabolism is the process of substances flow into the cell and convert them to specific molecular complexes which characterized by cells. This process goes with the flow of energy. Synthesis of substances in animal cells is due to metabolism process in cytoplasm consists of:
1) products of digestion, which came from circulatory system. In the digestive tract the digested food turns to low-molecular organic substances: amino acids, nucleotides, carbohydrates – non-specific and identical for all nature. After they enter into cell and form the metabolic foundation.
2) catabolism products which are formed in cells. Catabolism is a set of biochemical processes of dissociation of macromolecules which cells release as energy of chemical bonds. Metabolism in cells supporting its stable molecular structure of both inorganic and organic compounds. Due to metabolism there are two very important functions have performed: (1) supported the structure of cells and (2) getting an energy that comes from organic matter.
Energy flow
There are many breakdown products turn into cell – monosaccharides, glycerol, lipids, amino acids and others. Together with product the energy «comes» into the cell that is «accumulated» in chemical bonds between molecules and atoms then converted into ATP by means of macroergic links between phosphoric acids.
The energy required to maintain stability of cellular systems: support structure, homeostasis and all anabolic functions.
For all animals the main process is tissue respiration. This is amount of biochemical reactions cleavage (dehydrogenation) of some organic compounds (glucose, lipids, amino acids, etc.), сompounds of hydrogen with oxygen in the mitochondria and the formation of H20 and also ATP. Cellular high-energy «fuel» in form of molecules of adenosine triphosphate (ATP), freely diffusing in the cell and certain «portions» gives energy for anabolic processes. Molecule of ATP is a nucleotide consisting of adenine, ribose and three residues of orthophosphoric acid. The processes of destruction of organic matter occurs in the mitochondrial matrix where the enzymes of oxidation and inner membrane containing ATP- synthetase forming ATP are present.
ATP and other energy-rich compounds called macroergic. Enzyme cleavage of phosphate of ATP is accompanied by forming a considerable amount of energy – 8 kcal (instead of 3 kcal of chemical bonds that are allocated during disconnection). This connection is called macroergic. The energy of ATP is converted in cells into various types of work:
chemical, osmotic, mechanical and others.
Anaerobic glycolysis which occurs in cytoplasm of cells is less effective due to the incomplete breakdown of glucose molecules. This process gives only 10% of the required energy. Products of glycolysis come in mitochondria, where fully oxidized and releases energy which is also converted into macroergic links of ATP.
Information streams There are three flows of information іn cells.
1. Cells perceive changes in the environment (mainly chemical signals) and can react with them. Adaptation provided with the change of activity or formation of new required enzymes and other macromolecules. Intracellular processes leading to the necessary changes of shape, size and functioning of cells. As a result, an adequate response to signals allows cells to adapt and survive in the environmental conditions that change.
2. Hereditary information is stored in molecules of DNA as the genetic code – a sequence of triplets of nucleotides. This information used to support structural and functional organization of cells and their long existence as a stable system. Information rewritten from DNA to RNA molecules that provide the necessary
