Mitochondria and lysosomes
The weight of the brain in relation to body weight is about 2%, but at the same time it consumes 12-17% of glucose and up to 20% of oxygen from the body’s total budget, and neither is stored for future use, but is used immediately. Glucose oxidation occurs in mitochondria, which serve as the energy stations of the cell. The more intense the activity of a cell, the more mitochondria it contains. In nerve cells they are fairly evenly distributed in the cytoplasm, but can move there and change their shape.
The diameter of mitochondria ranges from 0.4 to 1 µm, they have two membranes, an outer and an inner, each of which is slightly thinner than the cell membrane. The inner membrane has numerous shelf-like projections or cristae. Thanks to such cristae, the working surface of mitochondria increases significantly. Inside the mitochondria there is a fluid in which calcium and magnesium accumulate in the form of dense granules. The cristae and internal space of mitochondria contain respiratory enzymes, which oxidize the products of glycolysis - anaerobic breakdown of glucose, fatty acid metabolites, and amino acids. The released energy of these compounds is stored in adenosine triphosphoric acid (ATP) molecules, which are formed in mitochondria through phosphorylation of adenosine diphosphoric acid (ADP) molecules.
Mitochondria have their own DNA and RNA, as well as ribosomes on which some proteins are synthesized. This circumstance gives grounds to call mitochondria semi-autonomous organelles. Their lifespan is short and approximately half of the mitochondria present in the cell are renewed every 10-12 days: new mitochondria are formed to replace those that have exhausted their resources and have collapsed.
Lysosomes are vesicles with a diameter of 250-500 nm bounded by their own membrane, inside which they contain various proteolytic, i.e. protein breaking down enzymes. With the help of these enzymes, large protein molecules are divided into small ones or even amino acids. Lysosomal enzymes are synthesized on ER ribosomes, then enter the Golgi apparatus in transport vesicles, where a carbohydrate component is often added to them, thereby converting them into glycolipids. Next, the enzymes are packaged into the membrane of the Golgi apparatus and bud from it, thereby turning into a lysosome. The hydrolytic enzymes of lysosomes rid the cell of worn out or collapsing cytoplasmic structures and excess membranes that have become unnecessary. Worn or damaged organelles fuse with lysosomes and are digested by lysosomal enzymes.
How important such activity is can be judged by the manifestations of diseases that lead to excessive accumulation of certain substances in the cytoplasm only because they cease to be destroyed due to a deficiency of just one of the lysosomal enzymes. For example, in hereditary Tay-Sachs disease there is a deficiency of hexosaminidase, an enzyme that breaks down galactosides in nerve cells. As a result, all lysosomes become densely packed with these undigested substances, and such patients experience serious neurological disorders. Lysosome enzymes are capable of breaking down substances not only of internal, endogenous origin, but also compounds that enter the cell from the outside through phagocytosis or pinocytosis.
Cytoskeleton
The shape of the cell is determined by a network of fibrillar, i.e. fibrous proteins, which can belong to one of three types: 1) microtubules; 2) neurofilaments; 3) microfilaments (Fig. 1.6). Fibrillar proteins are assembled from repeating identical units - monomers. If we denote a monomer by the letter M, then the structure of a fibrillar protein can be simplified as M-M-M-M-M... So microtubules are assembled from tubulin molecules, microfilaments from actin molecules, and assembly and disassembly occurs as needed. In nerve cells, many, but not all, fibrillar proteins are oriented along processes - axons or dendrites.
Microtubules are the thickest elements of the cytoskeleton; they have the shape of hollow cylinders with a diameter of 25-28 nm. Each cylinder is formed from 13 subunits - protofilaments, each protofilament is assembled from tubulin molecules. The location of microtubules in a cell largely determines its shape. Microtubules serve as a kind of stationary rails along which some organelles move: secretory vesicles, mitochondria, lysosomes. The speed of such movement in the axon can exceed 15 mm/hour; this type of axonal transport is called fast.
The driving force behind fast transport is a special protein, kinesin, which at one end of the molecule connects to the organelle being transported, and at the other to a microtubule, along which it slides, using the energy of ATP to move. ATP molecules are associated with microtubules, and kinesin has the activity of ATPase, an enzyme that breaks down ATP.
Neurofilaments are formed by strands of monomers twisted in pairs. Two such twists wrap around each other, forming a protofilament. A twist of two protofilaments is a protofibril, and three helically twisted protofibrils are a neurofilament, a kind of rope having a diameter of about 10 nm. Neurofilaments are found in the cell more often than other fibrillar proteins; their elastic twisted structure creates the main framework of the cytoskeleton.
They retain silver nitrate well, with the help of which Golgi and then Ramon y Cajal stained nervous tissue, studied it and laid the foundation for the neural theory. In some degenerative brain lesions, such as in Alzheimer's disease, the most common cause of senile dementia, the shape of neurofilaments changes significantly; they gather into characteristic Alzheimer's tangles.
Microfilaments are among the thinnest elements of the cytoskeleton, their diameter is only 3-5 nm. They are formed from spherical actin molecules assembled like a double string of beads. Each actin monomer contains an ATP molecule, the energy of which provides contraction of microfilaments. Such contractions can change the shape of the cell, its axon or dendrites.
Summary
The elementary unit of all living organisms, the cell, is limited from the environment by a plasma membrane, which is formed by lipids and several types of proteins that determine the individuality of the cell. The passage of various substances through the cell membrane is carried out by several transport mechanisms. The cell nucleus contains genetic information encoded by a sequence of four nucleotides of DNA. This information is used to form proteins necessary for the cell with the participation of mRNA. Protein synthesis occurs on ribosomes, further transformations of protein molecules are carried out in the ER. Secretory granules are formed in the Golgi apparatus, designed to transmit information to other cells. Mitochondria provide the cell with the necessary amount of energy, while lysosomes remove unnecessary cell components. Cytoskeletal proteins create the shape of the cell and participate in the mechanisms of intracellular transport.
Mitochondria are the organelles of all eukaryotic cells. They are characterized by an abundance of internal membranes. Two membranes - outer and inner - separate them from the cytoplasm. Membranes form large internal compartments in mitochondria in which oxidative phosphorylation reactions occur. As a result of these processes, the energy of oxidation reactions is converted into energy contained in ATP molecules. At the same time, mitochondria are extremely efficient at using sugar and fatty acids for oxidation.
Mitochondria (Greek mitos-thread, chondros-grain) occupy a significant part of the cytoplasm in eukaryotic cells. Calculations show that there are about a thousand mitochondria per liver cell. This is approximately 20% of the total volume of cytoplasm and about 30-35% of the total amount of protein in the cell. In oocytes there are up to 300,000 mitochondria, in giant amoebas up to 500,000. There are fewer mitochondria in the cells of green plants than in animal cells.
Mitochondria were described at the end of the last century, since their sizes are quite large, they are comparable to the size of a bacterial cell, and are clearly visible using a light microscope. Typically, mitochondria are a cylinder with a diameter of 0.5 μm and a length of up to 1 μm. However, in different organisms the length of mitochondria varies widely from 7 to 10 μm. Branched spider-like mitochondria are present in yeast cells, muscle cells, and trypanosomes. They have a high enough density that they can be observed in living cells. Such observations using microfilm filming show that the shape of mitochondria in living cells is very variable; they are unusually mobile and plastic organelles. Within a minute, they can change their cylindrical shape 15-20 times, taking the form of bubbles, dumbbells, tennis rackets, they can bend and straighten.
The localization of mitochondria in cells is determined by two factors. Firstly, it depends on the location of other organelles and inclusions. In differentiated plant cells, mitochondria are moved to the periphery of the cell by the central vacuole; in meristem cells they are located more or less evenly. In dividing cells, mitochondria are also located peripherally, they are displaced by the fission spindle. The orientation of mitochondria can be determined by cytoplasmic microtubules. Secondly, mitochondria accumulate in energy-dependent areas of the cell. In skeletal muscles - between myofibrils, in spermatozoa they tightly wrap around the flagellum, in protozoa equipped with cilia, mitochondria lie at the base of the cilia under the plasma membrane. In nerve cells - near the synapses where the transmission of nerve impulses occurs. In secretory cells, mitochondria are associated with areas of rough ER.
A real opportunity to understand the fine structure of mitochondria and their functions appeared only after 1948, when methods for isolating mitochondria from cells were developed and their biochemical study began. Each mitochondrion is surrounded by two highly specialized membranes that play a major role in its function. These membranes form two isolated mitochondrial compartments - the intermembrane space and the inner matrix. The inner membrane forms numerous cristae, increasing its total surface.
The matrix contains a highly concentrated mixture of hundreds of different enzymes necessary for the oxidation of pyruvate, fatty acids, and citric acid cycle enzymes. 67% of all mitochondrial protein is contained in the matrix. The matrix contains its own DNA, represented by several identical molecules and is close to bacterial in the composition of nucleotides, in addition, it is also circular like that of bacteria. The mitochondrial matrix also includes specific mitochondrial ribosomes. Their properties are also close to bacterial (70S).
The presence of DNA, ribosomes and enzymes involved in the functioning of the mitochondrial genome indicates some autonomy of mitochondria.
ATP synthesis occurs in mitochondria based on the oxidation of organic substrates and phosphorylation of ADP. The release of energy during aerobic oxidation of food is called respiration.
Mitochondria are one of the most important components of any cell. They are also called chondriosomes. These are granular or thread-like organelles that are part of the cytoplasm of plants and animals. They are the producers of ATP molecules, which are so necessary for many processes in the cell.
What are mitochondria?
Mitochondria are the energy base of cells; their activity is based on the oxidation and use of energy released during the breakdown of ATP molecules. In simple language, biologists call it an energy production station for cells.
In 1850, mitochondria were identified as granules in muscles. Their number varied depending on growth conditions: they accumulate more in those cells where there is a high oxygen deficiency. This happens most often during physical activity. In such tissues, an acute lack of energy appears, which is replenished by mitochondria.
Appearance of the term and place in the theory of symbiogenesis
In 1897, Bend first introduced the concept of “mitochondrion” to designate a granular and filamentous structure in which they vary in shape and size: thickness is 0.6 µm, length - from 1 to 11 µm. In rare situations, mitochondria can be large and branched.
The theory of symbiogenesis gives a clear idea of what mitochondria are and how they appeared in cells. It says that the chondriosome arose in the process of damage to bacterial cells, prokaryotes. Since they could not autonomously use oxygen to generate energy, this prevented them from fully developing, while progenotes could develop unhindered. During evolution, the connection between them made it possible for progenotes to transfer their genes to eukaryotes. Thanks to this progress, mitochondria are no longer independent organisms. Their gene pool cannot be fully realized, since it is partially blocked by enzymes that are present in any cell.
Where do they live?
Mitochondria are concentrated in those areas of the cytoplasm where the need for ATP appears. For example, in the muscle tissue of the heart they are located near the myofibrils, and in spermatozoa they form a protective camouflage around the axis of the cord. There they generate a lot of energy to make the “tail” spin. This is how the sperm moves towards the egg.
In cells, new mitochondria are formed by simple division of previous organelles. During it, all hereditary information is preserved.
Mitochondria: what they look like
The shape of the mitochondria resembles a cylinder. They are often found in eukaryotes, occupying from 10 to 21% of the cell volume. Their sizes and shapes vary greatly and can change depending on conditions, but the width is constant: 0.5-1 microns. The movements of chondriosomes depend on the places in the cell where energy is rapidly wasted. They move through the cytoplasm using cytoskeletal structures for movement.
A replacement for mitochondria of different sizes, which work separately from each other and supply energy to certain zones of the cytoplasm, are long and branched mitochondria. They are able to provide energy to areas of cells located far from each other. Such joint work of chondriosomes is observed not only in unicellular organisms, but also in multicellular ones. The most complex structure of chondriosomes is found in the muscles of the mammalian skeleton, where the largest branched chondriosomes are joined to each other using intermitochondrial contacts (IMCs).
They are narrow gaps between adjacent mitochondrial membranes. This space has a high electron density. MMKs are more common in cells where they bind together with working chondriosomes.
To better understand the issue, you need to briefly describe the significance of mitochondria, the structure and functions of these amazing organelles.
How are they built?
To understand what mitochondria are, you need to know their structure. This unusual source of energy is spherical in shape, but often elongated. Two membranes are located close to each other:
- external (smooth);
- internal, which forms leaf-shaped (cristae) and tubular (tubules) outgrowths.
Apart from the size and shape of the mitochondria, their structure and functions are the same. The chondriosome is delimited by two membranes measuring 6 nm. The outer membrane of the mitochondria resembles a container that protects them from the hyaloplasm. The inner membrane is separated from the outer membrane by a region 11-19 nm wide. A distinctive feature of the inner membrane is its ability to protrude into the mitochondria, taking the form of flattened ridges.
The internal cavity of the mitochondrion is filled with a matrix, which has a fine-grained structure, where threads and granules (15-20 nm) are sometimes found. Matrix threads create organelles, and small granules create mitochondrial ribosomes.
At the first stage it takes place in the hyaloplasm. At this stage, the initial oxidation of substrates or glucose occurs to These procedures take place without oxygen - anaerobic oxidation. The next stage of energy production consists of aerobic oxidation and breakdown of ATP, this process occurs in the mitochondria of cells.
What do mitochondria do?
The main functions of this organelle are:
The presence of its own deoxyribonucleic acid in mitochondria once again confirms the symbiotic theory of the appearance of these organelles. Also, in addition to their main work, they are involved in the synthesis of hormones and amino acids.
Mitochondrial pathology
Mutations occurring in the mitochondrial genome lead to depressing consequences. The human carrier is DNA, which is passed on to offspring from parents, while the mitochondrial genome is passed on only from the mother. This fact is explained very simply: children receive the cytoplasm with chondriosomes enclosed in it along with the female egg; they are absent in sperm. Women with this disorder can pass on mitochondrial disease to their offspring, but a sick man cannot.
Under normal conditions, chondriosomes have the same copy of DNA - homoplasmy. Mutations can occur in the mitochondrial genome, and heteroplasmy occurs due to the coexistence of healthy and mutated cells.
Thanks to modern medicine, more than 200 diseases have been identified today, the cause of which was a mutation in mitochondrial DNA. Not in all cases, but mitochondrial diseases respond well to therapeutic maintenance and treatment.
So we figured out the question of what mitochondria are. Like all other organelles, they are very important for the cell. They indirectly take part in all processes that require energy.
Mitochondria and plastids have their own circular DNA and small ribosomes, through which they make part of their own proteins (semi-autonomous organelles).
Mitochondria take part in (the oxidation of organic substances) - they supply ATP (energy) for the life of the cell, and are the “energy stations of the cell.”
Non-membrane organelles
Ribosomes- these are organelles that deal with... They consist of two subunits, chemically consisting of ribosomal RNA and proteins. The subunits are synthesized in the nucleolus. Some of the ribosomes are attached to the EPS; this EPS is called rough (granular).
Cell center consists of two centrioles that form the spindle during cell division - mitosis and meiosis.
Cilia, flagella serve for movement.
Choose one, the most correct option. The cell cytoplasm contains
1) protein threads
2) cilia and flagella
3) mitochondria
4) cell center and lysosomes
Answer
Establish a correspondence between the functions and organelles of cells: 1) ribosomes, 2) chloroplasts. Write numbers 1 and 2 in the correct order.
A) located on the granular ER
B) protein synthesis
B) photosynthesis
D) consist of two subunits
D) consist of grana with thylakoids
E) form a polysome
Answer
Establish a correspondence between the structure of the cell organelle and the organelle: 1) Golgi apparatus, 2) chloroplast. Write numbers 1 and 2 in the order corresponding to the letters.
A) double membrane organelle
B) has its own DNA
B) has a secretory apparatus
D) consists of a membrane, bubbles, tanks
D) consists of thylakoids grana and stroma
E) single-membrane organelle
Answer
Establish a correspondence between the characteristics and organelles of the cell: 1) chloroplast, 2) endoplasmic reticulum. Write numbers 1 and 2 in the order corresponding to the letters.
A) a system of tubules formed by a membrane
B) the organelle is formed by two membranes
B) transports substances
D) synthesizes primary organic matter
D) includes thylakoids
Answer
Choose one, the most correct option. Single-membrane cell components -
1) chloroplasts
2) vacuoles
3) cell center
4) ribosomes
Answer
All of the following features, except two, can be used to describe the structural features and functioning of ribosomes. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) consist of triplets of microtubules
2) participate in the process of protein biosynthesis
3) form the spindle
4) formed by protein and RNA
5) consist of two subunits
Answer
All of the characteristics listed below, except two, are used to describe the cell shown in the figure. Identify two characteristics that “drop out” from the general list, write down the numbers under which they are indicated.
1) the presence of a nucleolus with chromatin
2) the presence of a cellulose cell membrane
3) presence of mitochondria
4) prokaryotic cell
5) ability for phagocytosis
Answer
1) the presence of chloroplasts
2) the presence of a developed network of vacuoles
3) presence of glycocalyx
4) presence of a cell center
5) ability for intracellular digestion
Answer
All of the characteristics listed below, except two, are used to describe the cell shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) the presence of chloroplasts
2) presence of glycocalyx
3) ability to photosynthesize
4) ability to phagocytose
5) ability for protein biosynthesis
Answer
All of the characteristics listed below, except two, are used to describe the cell shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) mitosis
2) phagocytosis
3) starch
4) chitin
5) meiosis
Answer
All of the characteristics listed below, except two, can be used to describe the cell shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) there is a cell membrane
2) the cell wall consists of chitin
3) the hereditary apparatus is contained in a ring chromosome
4) storage substance - glycogen
5) the cell is capable of photosynthesis
Answer
Choose two correct answers out of five and write down the numbers under which they are indicated in the table. Select double membrane organelles:
1) lysosome
2) ribosome
3) mitochondria
4) Golgi apparatus
5) chloroplast
Answer
Analyze the table. For each lettered cell, select the appropriate term from the list provided:
1) core
2) ribosome
3) protein biosynthesis
4) cytoplasm
5) oxidative phosphorylation
6) transcription
7) lysosome
Answer
Analyze the table “Structures of a eukaryotic cell.” For each cell indicated by a letter, select the corresponding term from the list provided.
1) glycolysis
2) chloroplasts
3) broadcast
4) mitochondria
5) transcription
6) core
7) cytoplasm
8) cell center
Answer
1) Golgi complex
2) synthesis of carbohydrates
3) single membrane
4) starch hydrolysis
5) lysosome
6) non-membrane
Answer
Analyze the table. For each lettered cell, select the appropriate term from the list provided.
1) double membrane
2) endoplasmic reticulum
3) protein biosynthesis
4) cell center
5) non-membrane
6) biosynthesis of carbohydrates
7) single membrane
8) lysosome
Answer
1) glycolysis
2) lysosome
3) protein biosynthesis
4) mitochondria
5) photosynthesis
6) core
7) cytoplasm
8) cell center
Answer
Analyze the table “Cell Structures”. For each cell indicated by a letter, select the corresponding term from the list provided.
1) glucose oxidation
2) ribosome
3) splitting of polymers
4) chloroplast
5) protein synthesis
6) core
7) cytoplasm
8) spindle formation
Answer
Analyze the table. For each lettered cell, select the appropriate term from the list provided.
1) double membrane
2) endoplasmic reticulum
3) breakdown of organic substances
4) Golgi complex
5) non-membrane
6) protein biosynthesis
7) single membrane
8) cell center
Answer
Analyze the table “Cell Organelles”. For each cell indicated by a letter, select the corresponding term from the list provided.
1) chloroplast
2) endoplasmic reticulum
3) cytoplasm
4) karyoplasm
5) Golgi apparatus
6) biological oxidation
7) transport of substances in the cell
8) glucose synthesis
Answer
1. Select two correct answers out of five and write down the numbers under which they are indicated in the table. Cytoplasm performs a number of functions in a cell:
1) communicates between the nucleus and organelles
2) acts as a matrix for the synthesis of carbohydrates
3) serves as the location of the nucleus and organelles
4) transmits hereditary information
5) serves as the location of chromosomes in eukaryotic cells
Answer
2. Identify two true statements from the general list, and write down the numbers under which they are indicated. Cytoplasm performs functions in the cell
1) the internal environment in which the organelles are located
2) glucose synthesis
3) relationships between metabolic processes
4) oxidation of organic substances to inorganic ones
5) synthesis of ATP molecules
Answer
Choose two correct answers out of five and write down the numbers under which they are indicated. Select non-membrane organelles:
1) mitochondria
2) ribosome
3) core
4) microtubule
5) Golgi apparatus
Answer
The following features, except two, are used to describe the functions of the cell organelle depicted. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) serves as an energy station
2) breaks down biopolymers into monomers
3) provides packaging of substances from the cell
4) synthesizes and accumulates ATP molecules
5) participates in biological oxidation
Answer
Establish a correspondence between the structure of the organelle and its type: 1) cell center, 2) ribosome
A) consists of two perpendicularly located cylinders
B) consists of two subunits
B) formed by microtubules
D) contains proteins that ensure the movement of chromosomes
D) contains proteins and nucleic acid
Answer
Establish the sequence of structures in a eukaryotic plant cell (starting from the outside)
1) plasma membrane
2) cell wall
3) core
4) cytoplasm
5) chromosomes
Answer
Choose three options. How are mitochondria different from lysosomes?
1) have outer and inner membranes
2) have numerous outgrowths - cristae
3) participate in the processes of energy release
4) in them, pyruvic acid is oxidized to carbon dioxide and water
5) in them biopolymers are broken down into monomers
6) participate in metabolism
Answer
1. Establish a correspondence between the characteristics of a cell organelle and its type: 1) mitochondria, 2) lysosome. Write numbers 1 and 2 in the correct order.
A) single-membrane organelle
B) internal contents - matrix
D) the presence of cristae
D) semi-autonomous organelle
Answer
2. Establish a correspondence between the characteristics and organelles of the cell: 1) mitochondria, 2) lysosome. Write numbers 1 and 2 in the order corresponding to the letters.
A) hydrolytic cleavage of biopolymers
B) oxidative phosphorylation
B) single-membrane organelle
D) the presence of cristae
D) formation of a digestive vacuole in animals
Answer
3. Establish a correspondence between the feature and the cell organelle for which it is characteristic: 1) lysosome, 2) mitochondria. Write numbers 1 and 2 in the order corresponding to the letters.
A) the presence of two membranes
B) accumulation of energy in ATP
B) the presence of hydrolytic enzymes
D) digestion of cell organelles
D) formation of digestive vacuoles in protozoa
E) breakdown of organic substances to carbon dioxide and water
Answer
Establish a correspondence between the cell organelle: 1) cell center, 2) contractile vacuole, 3) mitochondria. Write numbers 1-3 in the correct order.
A) participates in cell division
B) ATP synthesis
B) release of excess fluid
D) “cellular respiration”
D) maintaining a constant cell volume
E) participates in the development of flagella and cilia
Answer
1. Establish a correspondence between the name of organelles and the presence or absence of a cell membrane: 1) membranous, 2) non-membrane. Write numbers 1 and 2 in the correct order.
A) vacuoles
B) lysosomes
B) cell center
D) ribosomes
D) plastids
E) Golgi apparatus
Answer
2. Establish a correspondence between cell organelles and their groups: 1) membrane, 2) non-membrane. Write numbers 1 and 2 in the order corresponding to the letters.
A) mitochondria
B) ribosomes
B) centrioles
D) Golgi apparatus
D) endoplasmic reticulum
E) microtubules
Answer
3. Which three of the listed organelles are membranous?
1) lysosomes
2) centrioles
3) ribosomes
4) microtubules
5) vacuoles
6) leucoplasts
Answer
1. All but two of the cell structures listed below do not contain DNA. Identify two cell structures that “drop out” from the general list and write down the numbers under which they are indicated.
1) ribosomes
2) Golgi complex
3) cell center
4) mitochondria
5) plastids
Answer
2. Select three cell organelles containing hereditary information.
1) core
2) lysosomes
3) Golgi apparatus
4) ribosomes
5) mitochondria
6) chloroplasts
Answer
3. Choose two correct answers out of five. In what structures of eukaryotic cells are DNA molecules localized?
1) cytoplasm
2) core
3) mitochondria
4) ribosomes
5) lysosomes
Answer
Choose one, the most correct option. Where in the cell are there ribosomes, except for the ER?
1) in the centrioles of the cell center
2) in the Golgi apparatus
3) in mitochondria
4) in lysosomes
Answer
What are the features of the structure and functions of ribosomes? Choose the three correct options.
1) have one membrane
2) consist of DNA molecules
3) break down organic substances
4) consist of large and small particles
5) participate in the process of protein biosynthesis
6) consist of RNA and protein
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. What processes occur in the cell nucleus?
1) formation of the spindle
2) formation of lysosomes
3) doubling of DNA molecules
4) synthesis of mRNA molecules
5) formation of mitochondria
6) formation of ribosomal subunits
Answer
Establish a correspondence between the cell organelle and the type of structure to which it is classified: 1) single-membrane, 2) double-membrane. Write numbers 1 and 2 in the order corresponding to the letters.
A) lysosome
B) chloroplast
B) mitochondria
D) EPS
D) Golgi apparatus
Answer
Establish a correspondence between the characteristics and organelles: 1) chloroplast, 2) mitochondria. Write numbers 1 and 2 in the order corresponding to the letters.
A) the presence of stacks of grains
B) synthesis of carbohydrates
B) dissimilation reactions
D) transport of electrons excited by photons
D) synthesis of organic substances from inorganic ones
E) the presence of numerous cristae
Answer
All of the characteristics listed below, except two, can be used to describe the cell organelle shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) single-membrane organelle
2) contains fragments of ribosomes
3) the shell is riddled with pores
4) contains DNA molecules
5) contains mitochondria
Answer
The terms listed below, except two, are used to characterize the cell organelle, indicated in the figure by a question mark. Identify two terms that “drop out” from the general list and write down the numbers under which they are indicated.
1) membrane organelle
2) replication
3) chromosome divergence
4) centrioles
5) spindle
Answer
Establish a correspondence between the characteristics of a cell organelle and its type: 1) cell center, 2) endoplasmic reticulum. Write numbers 1 and 2 in the order corresponding to the letters.
A) transports organic substances
B) forms a spindle
B) consists of two centrioles
D) single-membrane organelle
D) contains ribosomes
E) non-membrane organelle
Answer
Establish a correspondence between the characteristics and organelles of the cell: 1) nucleus, 2) mitochondria. Write the numbers 1 and 2 in the order they correspond to the numbers.
A) closed DNA molecule
B) oxidative enzymes on cristae
B) internal contents - karyoplasm
D) linear chromosomes
D) the presence of chromatin in interphase
E) folded inner membrane
Answer
Establish a correspondence between the characteristics and organelles of the cell: 1) lysosome, 2) ribosome. Write numbers 1 and 2 in the order corresponding to the letters.
A) consists of two subunits
B) is a single-membrane structure
B) participates in the synthesis of the polypeptide chain
D) contains hydrolytic enzymes
D) located on the membrane of the endoplasmic reticulum
E) converts polymers into monomers
Answer
Establish a correspondence between the characteristics and cellular organelles: 1) mitochondria, 2) ribosome. Write numbers 1 and 2 in the order corresponding to the letters.
A) non-membrane organelle
B) presence of own DNA
B) function - protein biosynthesis
D) consists of large and small subunits
D) the presence of cristae
E) semi-autonomous organelle
Answer
All of the features listed below, except two, are used to describe the cell structure shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) consists of RNA and proteins
2) consists of three subunits
3) synthesized in hyaloplasm
4) carries out protein synthesis
5) can attach to the EPS membrane
Answer
© D.V. Pozdnyakov, 2009-2019
A. Photosynthesis.
B. Chemosynthesis.
B. Energy metabolism.
D. Plastic exchange .
40. Viruses contain:
A. DNA only.
B. RNA only.
B. Either DNA or RNA.
D. Together DNA and RNA.
41. Which metal atoms are included in the composition of red blood cells:
B. Gland.
G. Magnesium.
42. Colorless blood cells capable of amoeboid movement through the walls of blood vessels:
A. Red blood cells.
B. Leukocytes.
B. Thrombocytes.
G. Platelets.
43. Blood cells capable of producing antibodies:
A. Leukocytes.
B. Platelets.
B. Lymphocytes.
G. Red blood cells.
44. How are the molecules of liquids arranged and how do they move?
A. Molecules are located at distances commensurate with the size of the molecules themselves, and move freely relative to each other.
B. Molecules are located at large distances (compared to the size of the molecules) from each other and move randomly.
B. Molecules are arranged in a strict order and vibrate around certain equilibrium positions.
45. Which of the following properties belong to gases? (3 answer options)
A. They occupy the entire volume provided to them.
B. Difficult to compress.
B. They have a crystalline structure.
D. Easily compressed.
D. They do not have their own shape.
46. A beaker contains water with a volume of 100 cm3. It is poured into a glass with a capacity of 200 cm3. Will the volume of water change?
A. Will increase.
B. Will decrease.
B. It won’t change.
47. Molecules are tightly packed, strongly attracted to each other, each molecule vibrates around a certain position. What kind of body is this?
B. Liquid.
B. Solid body.
D. There are no such bodies.
48. In what state can water be?
A. Only in a liquid state.
B. Only in the gaseous state.
B. Only in the solid state.
D. In all three states.
49. Is there a substance in which the molecules are located at large distances, are strongly attracted to each other and vibrate around certain positions?
B. Liquid.
B. solid body.
D. Such a substance does not exist.
50. Indicate substances that have a protein nature:
A. Enzymes.
B. Hormones.
B. Lipids.
G. Carbohydrates.
D. Pigments.
E. Amino acids.
51. Select a function that is performed almost exclusively by proteins in the body:
A. Energy.
B. Regulatory.
B. Informational.
G. Enzymatic.
52. Polysaccharides include:
A. Sucrose.
B. Ribose.
B. Starch.
G. Glucose .
53. From the list below, select: 1) monosaccharides; 2) disaccharides.
A. Glucose.
B. Ribose.
B. Sucrose.
G. Fructose.
D. Maltose.
Option 3
1. The force resulting from the deformation of a body and directed in the direction opposite to the movement of particles of the body is called:
A. elastic force.
B. gravity.
B. body weight.
2. A person whose mass is 80 kg holds a bag weighing 10 kg on his shoulders. With what force does a person press on the ground?
3. Determine the kinetic energy of a body weighing 200 g, which moves at a speed of 72 m/s.
4. Is work being done and if so, what sign?
Example: A load weighing 120 kg is lifted to a height of 50 cm;
5. The force of gravity is a force conditioned by:
A. Gravitational interaction.
B. Electromagnetic interaction.
B. Both gravitational and electromagnetic interaction.
6. What is Boltzmann's constant?
A. 1.3 * 1012 kg/mol.
B. 1.38 * 1023 K/J.
V. 1.38 * 10-23 J/K.
G. 1.3 * 10-12 mol/kg.
7. What are the names of the phenomena caused by changes in body temperature?
A. Electrical.
B. Thermal.
B. Magnetic.