This "High School Biology Lesson Plan: Flow Mosaic Model of Biomembrane" is compiled for everyone. I hope it will be helpful to everyone. The following information is for reference only! ! !
Section 2 Flow Mosaic Model of Biofilm
Course Standard Requirements
1. Briefly describe the basic contents of the flow mosaic model of biofilm
2. Give an example of the fluidity characteristics of biological membranes
3. Give an example of a cell membrane that is a selectively permeable membrane
4. The components and functions of a cell membrane
5. Scientists’ exploration process of cell membrane structure
Knowledge network system
Basic scaffolding phospholipid bilayer
Protein mosaic asymmetry
Structural characteristics of biological membranes: Fluidity
The surface of the cell membrane consists of sugar coat and glycolipids
The main components are phospholipids, proteins and a small amount of sugars
Functional characteristics Selective permeability
Summary of major difficulties and hot spots
1. The process of exploring the structure of biofilms
The scientific experimental hypothesis of time scientists
At the end of the 19th century
Irvington
conducted tens of thousands of permeability experiments on plant cells using more than 500 substances and found that lipids are easier to pass through the cell membrane. Membranes are composed of lipids.
In 1925, two Dutch scientists extracted lipids from the cell membrane and spread them into a single layer of molecules with an area twice that of the cell membrane. The lipids in the cell membrane were two continuous layers
1959 Robertson saw under the electron microscope that the cell membrane is composed of a three-layer structure of "protein-lipid-protein" and that the biological membrane is a three-layer static unified structure
In 1970 Frey and Eddyn
< p> Labeled the proteins of two cells with green and red fluorescent dyes respectively, and fused the two cells, and found that the uniformly fluorescent cell membrane was fluid1972 Sanger and Nickerson
The flow mosaic model is proposed based on new observations and experimental evidence
*There are many molecular structure models of biological membranes, the more popular ones are the "flow mosaic model"
2. Biology The basic characteristics of the membrane molecular structure are:
(1) Mosaicism: The basic structure of the membrane is composed of lipid bilayers embedded in proteins
(2) Fluidity: Membrane structure The protein and lipid molecules in the membrane can move in various forms. The overall structure of the membrane is also fluid. The important physiological significance of fluidity: material transport, cell recognition, cell fusion, cell surface receptor function regulation, etc.
(3) Asymmetry: The molecular properties and structures on both sides of the membrane are different
(4) Protein polarity: The polar region of the polypeptide chain protrudes toward the membrane surface and is not The polar part is buried inside the lipid bilayer. Therefore, protein molecules have affinity with both water-soluble and fat-soluble molecules.
3. Basic contents of the flow mosaic model
Structural characteristics:
(1) Phospholipid bilayer: the basic scaffold that constitutes the membrane
< p> (The hydrophilic head of the phospholipid molecule faces both sides, and the hydrophobic tail faces inward)(2) Protein molecules: on the membrane surface, or partially or completely embedded in the phospholipid bilayer< /p>
Sugar coat (a small amount): the surface of the cell membrane
Functional characteristics:
(3) Lipid molecules can move and are fluid;
< p> (4) The protein molecules of the membrane can also move. (Also reflects the fluidity of the membrane)(5) On the surface of the cell membrane, there is a layer of glycoprotein formed by the combination of proteins on the cell membrane and sugars
called the glycocoat. (The sugar coat is closely related to cell recognition, intercellular information exchange, etc.)
4. Why is the cell membrane said to be a selectively permeable membrane?
The transmembrane transport of water molecules follows the relative content gradient. This is not always the case for the transmembrane transport of other substances, depending on the needs of cell life activities. Cells absorb substances selectively.
Conclusion: The cell membrane is not only a semipermeable membrane, but also a selectively permeable membrane
Analysis of classic examples
Example 1 Amoeba can phagocytose whole bacteria. This Fact statement ( ).
A. The cell membrane has selective permeability; B. The cell membrane has total permeability;
C. The cell membrane has a certain fluidity; D. The cell membrane has a protective effect.
Answer C
Analysis The knowledge point assessed in this question is the structural characteristics of the cell membrane, but it asks students to analyze it through an example, requiring students to apply the knowledge they have learned. to get the correct answer. Many students will mistakenly choose A. This option is the functional characteristic of the cell membrane, but it is inconsistent with the question situation.
Example 2 (2004 Hubei Simulation Question) There are some red substances in the cell fluid of amaranth. No matter how you wash it with water, the red substance is still not visible in the water. But if you put the amaranth into boiling water and scald it, The water immediately turned red. This phenomenon is because
A. Boiling water causes the cell membrane to lose its permselectivity. B. The cell membrane has no permselectivity in clear water.
C. Pigments decompose into small molecular substances in boiling water. D .No matter enters or exits in clear water
[Analysis] The structural characteristic of the cell membrane is fluidity, and the physiological function of the cell membrane is selective permeability, which is a unique function of living cells. Under normal circumstances, pigments and other substances are macromolecules and are needed by cells. The cell membrane of living cells will not allow them to escape easily, so in clear water, red pigments will not come out. If put into boiling water, the high temperature will kill the cells, destroy their structure, and make the cell membrane inactive. The cell membrane will become permeable. After losing its selectivity, the pigment substances in the cell can come out without restriction. So the water turns red.
[Answer] A
Basic question training
1. Multiple choice questions
1. According to research, cholesterol and small molecule fatty acids , vitamin D and other substances are easier to pass through the cell membrane preferentially. This is because ( )
A The cell membrane has a certain fluidity B The cell membrane is selectively permeable
C The structure of the cell membrane is based on phospholipids The molecular layer is the basic skeleton D. The cell membrane is inlaid with various protein molecules
2. Which of the following membrane structures can pass biological macromolecules ( )
A. Cell membrane B. Nuclear membrane C. Mitochondria Membrane C Chloroplast membrane
3. A molecule of CO2 diffuses out from the mitochondrial matrix of the mesophyll cell and enters the chloroplast matrix of an adjacent cell. The number of biofilm layers it passes through is ( )< /p>
A 5 ??B 6 C 7 D 8
4. The chemical substance on the cell membrane that is closely related to cell recognition, immune response, information transmission and blood type determination is ( )
A Glycoprotein B Phospholipid C Fat D Nucleic acid
5. Pseudopodia can be extended from any part of the amoeba, and some white blood cells of the human body can engulf germs. The completion of these physiological processes depends on the cell membrane. ( )
A Protection B Certain mobility C Active transport D Permselectivity
6. Among the following substances, the one that cannot cross the cell membrane to enter or leave the cell is ( )
A Vitamin D and sex hormones B Water and urea C Amino acids and glucose D Enzymes and insulin
7. Proteins on biological membranes are usually combined with polysaccharides to form glycoproteins. In cellular life activities, glycoproteins play important functions in cell recognition and information transmission inside and outside the cell. Among the following biological structures, the one with the highest glycoprotein content may be ( )
A. Thylakoid membrane B. Mitochondrial membrane C. Cell membrane D. Endoplasmic reticulum membrane
8 , water-soluble stain PI, which can combine with nucleic acids to color cell nuclei, and can be used to identify dead and alive cells. When cells are soaked in a certain concentration of PI, only the nuclei of dead cells will be stained, while living cells will not be stained. However, when PI is injected into the cells, the nuclei will be stained.
The basic principle of using PI to identify cells is ( )
A. The nucleic acid structures of dead cells and living cells are different B. The nucleic acid content of dead cells and living cells is different
C. Living cells can break down the dye PI D. The cell membrane of living cells prevents the entry of PI
9. Based on the data in the table, indicate which of the following statements is wrong ( )
Ingredients
Mitochondrial membrane proteins
p>(Mass fraction/%) Lipids
(Mass fraction/%)
Outer membrane 52 48
Intima 76 24
A. The inner membrane contains many enzymes related to aerobic respiration B. The inner membrane has more functions than the outer membrane
C. The chemical composition of the inner membrane and the outer membrane is roughly the sameD .The inner membrane surface area is large, resulting in high protein content
10. A scientist discovered that when the temperature rises to a certain level, the thickness of the cell membrane becomes smaller and the area increases. This is due to what characteristics of the cell membrane? What was decided? ( )
A. It is a selectively permeable membrane B. It has certain fluidity C. It has specificity D. It has the function of transporting substances
11. Structure of biological membrane The characteristics are
A. The phospholipid molecules that make up the biological membrane can move
B. The protein molecules that make up the biological membrane can move
C. The phospholipids that make up the biological membrane Molecules and protein molecules are stationary
D. Phospholipid molecules and most protein molecules that constitute biological membranes can move
12. The recognition function of cell membranes is mainly determined by
< p> A. Cholesterol B, protein C, phospholipid D, sugar13. What is not a component of the cell membrane
A. protein B, sugar C, lipid D, nucleic acid
14. Which of the following statements is correct
A. Phospholipid molecules play an important role in the function of cell membranes, so the functions are complex, and the types and numbers of phospholipid molecules are many
< p> B. Phospholipid molecules play an important role in the function of the cell membrane, so the function is complex. The type and number of phospholipid molecules must be the sameC. Protein molecules play an important role in the function of the cell membrane, so the function is complex. , the type and number of protein molecules are greater
D. Protein molecules play an important role in the function of the cell membrane, so the function is complex, the type and number of protein molecules are the same
15. The cell wall The functional characteristics are
A. Total permeability B. Semi-permeability C. Impermeability D. Selective permeability
16. The chemical composition of the cell wall is
< p> A. Cholesterol and cellulose B. Cellulose and pectin C. Pectin and phospholipid D. Phospholipid and protein17. Oxygen in the blood enters the mitochondria of muscle cells for aerobic respiration, at least The number of membranes and phospholipid layers to pass through is
A, 3, 6, B, 3, 3 C, 2, 4 D, 2, 2
18. Macromolecular protein The structures that can pass through are
A. Mitochondrial membrane and chloroplast membrane B. Cell membrane and tonoplast membrane C. Selective permeability membrane D. Cell wall and nuclear pore
19. Scientists will lactation Mature red blood cells of animals or humans are put into distilled water, causing the red blood cells to rupture and cause hemolysis. The dissolved extracellular substances are then washed away. The remaining structure is called "blood shadow" in biology. So, the main component of the blood shadow is have( ).
A． Inorganic salts, proteins B. Protein, carbohydrate C. Fat, protein D. Lipids, proteins
20. Among the following descriptions of the structure and composition of various biological membranes in cells, which one is incorrect ( ).
A． Mainly composed of protein, lipids and a small amount of sugar
B. The phospholipid bilayer is the basic skeleton of various biological membranes
C. The types and amounts of proteins on different biological membranes are different
D. The endoplasmic reticulum membrane can generate the Golgi membrane, indicating that the chemical composition of the two is exactly the same
21. Generally, the cell membrane of plant cells cannot be seen under a light microscope. In which of the following cases, can it be seen? to the cell membrane ( ).
A. When cells divide B. When plasmolysis occurs
C. When the microscope field of view is brightened D. When cells absorb water and ions
22. Scientists extracted the phospholipid component of the cell membrane and spread it into a monolayer on the "air-water" interface. They found that the surface area of ??this monolayer was quite twice the surface area of ??the original cell membrane. This shows that the distribution of phospholipid molecules on the cell membrane is ( ).
A. Single layer arrangement B. Uniform and sparse arrangement C. Double layer arrangement D. Evenly and closely arranged
23. Among the following statements about the properties of cell membranes, which one is wrong ( ).
A. With mobility and selective permeability B. Proteins are evenly distributed on the phospholipid bilayer
C. Small lipid molecules are easy to diffuse freely through D. Both the inner and outer surfaces of the phospholipid bilayer are hydrophilic
24. Which of the following statements is not a structural feature of the cell membrane? ( )
A. The cell membrane is a selectively permeable membrane B. The cell membrane is composed of phospholipid molecules and protein molecules
C. The molecular structure of the cell membrane is fluid D. Some protein molecules can move between the inside and outside of the membrane
25. The characteristic that makes phospholipids particularly suitable for forming cell membranes is ( ).
A. They are hydrophobic B. They are hydrophilic
C. They absorb water quickly D. They are both hydrophilic and hydrophobic
26. If the plant cell membrane changes from a selectively permeable membrane to a fully permeable membrane, the cell will ( ).
A. Zoom out b. Expansion c. death d. Growth
27. (Multiple choice question) Among the following statements about cell membranes, which one is correct
A. Phospholipid molecules are arranged into a bilayer
B. The arrangement of substance molecules on both sides of the membrane is asymmetrical
C. Globular protein molecules are covered or embedded in the phospholipid bilayer
D. The movement of the substances that make up the membrane gives it a certain flow Sex
2. Non-choice questions
1. Based on the chemical composition and structural characteristics of the cell membrane, analyze the following materials and answer relevant questions:
(1) 1895 When Overton was studying the permeability of various unfertilized egg cells in 1998, he discovered that fat-soluble substances easily penetrate the cell membrane, while it is very difficult for lipid-insoluble substances to penetrate the cell membrane. This shows that among the main components that make up the cell membrane are _______________.
(2) In 1925, Gorter Grendel used acetone to extract the lipids of the red blood cell membrane and spread it on the air-water interface. The area of ??this single layer of molecules was equivalent to twice the original surface area of ??the red blood cells. . It can be said that the cell membrane is composed of _________.
(3) Scientists use green and red fluorescent dyes to mark proteins on human and mouse cell membranes respectively, and then fuse the two cells into one cell. Initially, half of the membrane fluoresces green and the other half fluoresces red. After a period of time, the fluorescent dots of the two colors are evenly distributed, as shown in the figure below:
① The results of this experiment indicate that the cell membrane _______________, because ________________________________________
_______________________________.
② If the fused cells are kept at 0°C for 40 minutes after the two cells fuse into one cell, half of the membrane of the fused cell will still fluoresce green and the other half will fluoresce red. This means ____________________.
③The virus melting agent commonly used in cell fusion is _________.
2. The process of exploring the structure of biological membranes
At the end of the 19th century, Irvington’s experiments and inferences: membranes are composed of;
At the beginning of the 20th century, Scientists' chemical analysis results indicate that membranes are mainly composed of , the fusion experiment of fluorescently labeled mouse cells and human cells pointed out that the cell membrane has;
In 1972, Sanger and He proposed.
3. Adjacent phospholipid molecules that make up the cell membrane change positions 1 million times per minute, which indicates that the cell membrane has _________ characteristics.
4. The process of scientists studying the structure of cell membranes began with the phenomenon of _______________. __________ is the basis for understanding structure, and __________ provides clues for exploring structure. People put forward hypotheses based on __________, and then revised the hypotheses through further __________, in which the progress of __________ played a key role.
5. When someone studied the permeability of unfertilized egg cells, they found that fat-soluble substances can easily pass through the cell membrane, while substances that are insoluble in lipids cannot easily pass through the cell membrane. It can be seen that there must be some substance in the chemical composition of the cell membrane that is conducive to the passage of lipid substances. Extract this substance and spread it into a monomolecular layer at the air-water interface. The area of ??this molecular layer is equivalent to twice the original cell surface area. Based on the above facts, it is speculated:
(1) This chemical component on the cell membrane is __________.
(2) The distribution of this chemical component on the cell membrane is: ____________________.
6. In human and mouse cell fusion experiments, two types of antibodies are labeled with two fluorescent substances to bind to antigenic substances on the surface of mouse and human cell membranes respectively (Figure 4-7). Experimental results show that when cells begin to fuse, the surface antigens of human and mouse cells are "differentiated" and each is only distributed on the surface of their respective cells; but after fusion, the two antigens are evenly distributed on the surface of the fused cells. Please analyze and answer the following questions.
Figure 4-7
(1) Cell fusion experiments show that the __________ molecules that make up the cell membrane can move, which also proves that the cell membrane has __________ Features.
(2) In cell fusion experiments, an antibody can only bind to the corresponding antigen, indicating that this type of substance has __________ properties in its molecular structure.
(3) If the cell fusion experiment is performed at 20°C, the time for the two surface antigens to be evenly distributed will be greatly extended, which shows that ____________________________. If it is under 1°C, it is difficult for the two surface antigens to be evenly distributed, which also illustrates ____________________________.
Innovative application training
1. The following materials show the researchers’ research on cell components and structures.
Please analyze according to the materials:
Material 1: Researchers treat mammal (or human) red blood cells with hypotonicity to cause hemolysis, causing hemoglobin and inorganic salts to dissolve out of the cells, leaving "empty shells" (called blood shadows), and Perform chemical composition analysis. Through blood shadow studies and other methods, the chemical composition of various membranes was measured, as shown in the table:
Protein (%)
Lipids (mainly phospholipids) (%)
p>Carbohydrates (%)
Human red blood cell membrane
49
43
8
Mouse liver cell membrane
44
52
4
Amoeba membrane
54
42
4
Inner mitochondrial membrane
76
24
0
Spinach chloroplast lamellar membrane
70
30
0
(1) Blood shadow can be inferred from the above processing It is pure material and can be used for research.
(2) The above data shows that the chemical components that make up the cell membrane are mainly that there are some differences in the types of chemical substances that make up the cell membrane and the intracellular membrane (making up the organelle membrane). These differences may cause the difference between the two. difference.
Material 2 uses acetone to extract lipids (mainly phospholipids) from cell membranes, then place the extracted lipids in a special water tank to make it into a monolayer, and measure its surface area. The measurements were compared with the surface area of ??red blood cells and were found to be twice as large.
The picture on the right is a model diagram of a phospholipid molecule. A phospholipid molecule is composed of a hydrophilic polar head and a hydrophobic tail.
(3) According to the information given in Material 2, it can be inferred that the phospholipid molecules in the cell membrane are arranged in a
form. According to the aqueous solution environment inside and outside the cell membrane and the characteristics of the phospholipid molecules, please Specify the arrangement of phospholipid molecules in the cell membrane (refer to the phospholipid molecular pattern diagram) and draw a simple schematic diagram.
Material 3 The researchers used red fluorescence to label antibodies (proteins) on the human cell membrane, and green fluorescence to label the antibodies on the mouse cell membrane, and then fused the two. Start with half green and half red. The two fluorescences were found to be evenly distributed after 40 minutes at 37°C.
(4) Description of this experiment.
Based on the above experiments and other experiments, scientists proposed the "flow mosaic model" of the cell membrane.
2. Use the following materials to design an experiment to verify that the cell membrane of living cells has selective permeability, while the cell membrane of dead cells loses selective permeability.
Experimental materials and utensils: brightly colored flowers, test tubes, small beakers, alcohol lamps, matches, test tube clamps, petri dishes, water
Ask questions:
Make assumptions:
Predict experimental results:
Experimental steps:
Section 2 Flow mosaic model of biofilm
1. Multiple choice questions
1-5 CBAB 6-10 DCDDB 11-15 DBDCA 16-20 BADDD 21-26 BCBADC 27 ABD
2. Non-choice questions
1. (1) Lipid molecules
(2) Phospholipid bilayer (or two layers of phospholipid molecules)
(3) ① Mobility of protein molecules with certain fluidity Caused by ②The activity of protein molecules is affected by temperature ③Sendai virus
2. Lipid lipid protein protein-lipid-protein fluidity Nickerson flow mosaic model
3. Movement (flow)
4. Transmembrane transport of substances Analysis of composition phenomena and functions Experimental observation Experimental methods and techniques
5. (1) Phospholipids (2) Two consecutive layers
p>6. (1) Protein fluidity (2) Specificity (3) As the ambient temperature decreases, the movement of protein molecules on the membrane slows down. When the ambient temperature is very low, the movement of protein molecules on the membrane almost stops.
3. Innovative application questions
(1) Cell membrane
(2) Lipids (or phospholipids) and proteins; functions
(3) Bilayer;
(4) The protein molecules that make up the cell membrane can move, and the phospholipid bilayer also has a certain fluidity (or the fluidity of the cell membrane)
2. Ask questions:
Are the pigments in the living cells of flowers selected? Can they come out? What about dead cells?
Make hypotheses:
The pigments in living cells are not selectively discharged, and the membranes of dead cells lose their selectivity and leak out.
Predict the experimental results:
When flowers are placed in water, the water does not change color; when heated Kill the cells, and after a period of time, the water will change color.
Experimental steps:
1. Soak the flowers in water for a period of time, and the water will not change color.
(As a control group)
2. Put some flowers into water and heat and boil to kill the cells and cool. After a period of time, the water will change color
Conclusion:
< p> The experimental phenomenon is consistent with the prediction, indicating that the cell membrane of living cells is selectively permeable, while the cell membrane of dead cells loses selective permeability, and substances can freely diffuse in