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MindMap Gallery cells (raw)
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cells (raw)
Cell (Life), which summarizes knowledge points such as cell wall and cell membrane, cytoplasm, biofilm system, and cell nucleus. Hope this mind map helps you!
Edited at 2024-02-15 23:48:09
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cells (raw)
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This article discusses the Easter eggs and homages in Zootopia 2 that you may have discovered. The main content includes: character and archetype Easter eggs, cinematic universe crossover Easter eggs, animal ecology and behavior references, symbol and metaphor Easter eggs, social satire and brand allusions, and emotional storylines and sequel foreshadowing.
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- Outline
cell
cell wall and cell membrane
cell wall
plant cell wall
Cellulose, pectin
Cellulase and pectinase can be used to remove the cell wall to obtain protoplasts
Formation process: Cellulose synthesized by the Golgi body is transported to the middle of the cell through vesicles to form a cell plate structure. Multiple vesicles fuse with each other and gradually form a new cell wall; after the vesicles fuse with the cell membrane, they become part of the new cell membrane.
fungal cell wall
Chitin
Chitinase can be used to remove cell walls
bacterial cell wall
peptidoglycan
Function: The cell wall is relatively tough and supportive, supporting the cells, maintaining the normal shape of the cells, and protecting the internal structure of the cells.
cell membrane
Element
Paper: about 50%, mainly phospholipids, animal cells also contain cholesterol
Protein: about 40%, closely related to the function of the cell membrane; the more complex the function of the cell membrane, the more types and quantities of proteins
Sugar; 2% to 10%, mainly used to form glycoproteins or glycolipids, with protective and lubricating effects
Different cell membranes have the same types of components, but the amounts of each component are different.
During the process of cell carcinogenesis, cell membrane components change and glycoproteins decrease, which significantly reduces the adhesion activity between cancer cells and makes them easy to disperse and metastasize in the body; however, the number of certain glycoproteins increases, such as oncinoembryonic protein, which can be Tests to Diagnose Cancer
Preparation method
Experimental principle: cells absorb water and burst
Experimental materials: Mature red blood cells from humans or other mammals
Reason for material selection: Mature red blood cells of mammals, pure cell membranes without nuclei and many organelles. Animal cells have no cell walls, and cells easily rupture due to water absorption.
Structure (Liquidity)
Discovery journey
At the end of the 19th century, Irvington conducted cell permeability experiments: Substances soluble in lipids pass through the cell membrane more easily than substances insoluble in lipids, which led to the conclusion that the cell membrane is composed of lipids.
At the beginning of the 20th century, the cell membranes of mammalian red blood cells were extracted and chemically analyzed. The main components of the membranes were lipids and proteins.
In 1925, two scientists in the Netherlands extracted lipids from human red blood cells and spread them into a monolayer on the air-water interface. They measured that the area of the monolayer was twice the surface area of the red blood cells. From this, they concluded that the lipids in the cell membrane The lipid molecules must be arranged into two consecutive layers
In 1959, Robertson observed the dark-light-dark three-layer structure of the cell membrane through an electron microscope, deducing that all biological membranes are static structures composed of a protein-lipid-protein three-layer structure.
After the 1960s, the static structure of biological membranes was questioned. New technologies (scanning electron microscopy, etc.) found that membrane proteins were not all spread on the surface of paper, and some proteins were embedded in the lipid bilayer.
In 1970, fluorescent protein labeling and cell fusion techniques demonstrated that cell membranes are fluid.
In 1972, Sanger Nickerson proposed the flow mosaic model
Fluid tessellation model content
Suitable for all biofilms
The phospholipid bilayer forms the basic scaffolding of the membrane and is fluid The hydrophobic "tails" of the phospholipid bimolecules are connected and located in the center of the membrane
Some proteins are embedded on the surface of phospholipids, some are partially embedded in the phospholipid bilayer, and some penetrate the entire phospholipid bilayer. Most proteins can also move, and the transport of carrier proteins has molecular specificity.
On the surface of the cell membrane, there is a layer of glycoproteins formed by the combination of proteins and sugars on the cell membrane, called the glycocoat, which has the functions of protection, lubrication and cell recognition.
In addition to phospholipids, there are also some glycolipids and cholesterol in the cell membrane; the functions of lipids are similar to glycoproteins; cholesterol is unique to animal cell membranes; glycolipids and glycoproteins are distributed on the outer surface of the cell membrane;
Function (selective transparency)
Separates the cells from the external environment and ensures the relative stability of the internal environment of the cells.
Controls the entry and exit of substances into cells; required nutrients enter, while substances harmful to cells or unnecessary cannot easily enter; secretions such as antibodies, hormones, and metabolic waste of cells must be discharged outside the cells, but important substances such as nucleic acids will not be lost to the cells. outside The control effect of the cell membrane is relative. Some viruses and bacteria can also enter the cell.
communication between cells
Indirect: transmitting information through chemicals secreted by cells Endocrine cells → secrete hormones → enter body fluids → transport body fluids to target cell receptors → transmit information to target cells hormone → target cell
Direct: transfer of information through contact between the cell membranes of two adjacent cells Cell ←→ Recognition and combination between cells, such as sperm and egg cells
Plasmodesmata: Communication of information through channels formed between two adjacent cells (can transfer nutrients) Cell ⇌ Cell Higher plant cells communicate information through plasmodesmata
Functional basis
The functions of material transport and information exchange in the cell membrane are reflected by the proteins on the membrane. The proteins on the membrane mainly include carrier proteins and specific receptor proteins.
The role of carrier proteins is to transport materials, including active transport and assisted diffusion. Their specificity and quantity determine the type and quantity of material transported, reflecting the selective permeability of the cell membrane.
The role of specific receptor proteins is to transmit information
Features
Structural features
a certain amount of liquidity
Reason: Phospholipid molecules and most protein molecules in the membrane structure can move
Influencing factors: Mainly affected by temperature. Within an appropriate temperature range, as the external temperature increases, the fluidity of the membrane increases. However, if the temperature exceeds a certain range, the membrane will be damaged.
Examples: cell fusion, engulfment, vomiting, amoeba deformation, phagocytosis of pathogens by phagocytes, secretion of secretory proteins, sperm-egg union, plasmolysis and restoration of plant cells, etc.
Features
Selectivity
Reason: There is a carrier protein on the cell membrane, and the carrier protein is specific
Influencing factors: The type and quantity of carrier proteins determine the type and quantity of substances transported
Examples: Absorption of mineral ions by plant roots, absorption of nutrients by intestinal villous epithelial cells
Connection: Fluidity is the basis of permselectivity. Only fluidity of a membrane can achieve permselectivity. Only living cells have membrane fluidity and permselectivity. Dead cells will lose fluidity and membrane permselectivity. sex
application
Using mobility to perform animal cell fusion and plant somatic cell hybridization
In scientific research, the "staining exclusion method" is commonly used to identify living cells and dead cells. For example: dead animal cells stained with table blue will be stained blue, while living animal cells will not be stained. Principle: The cell membrane of living cells is selectively permeable
Membrane Protein
Receptor protein: Receptor for signaling molecules, which can also be directly contacted by cells for signal recognition.
Carrier protein: assists in the transport of substances across membranes (assisted diffusion, active transport)
Enzymes with catalysis: Active transport carriers on the cell membrane function as ATP hydrolases (releasing energy for active transport)
cytoplasm
cytoplasmic matrix
composition
Composition: water, inorganic salts, lipids, sugars, amino acids, nucleotides and various enzymes (there are thousands of enzymes, which are the main site of cell metabolism)
The cytoplasm, excluding the parts other than organelles, is in a colloid state.
It is called cytoplasmic matrix at the submicroscopic level; it is called cytosol in cell biochemistry (the supernatant part of the cell homogenate after ultracentrifugation to remove all organelles and particles)
Cytoskeleton refers to a network structure composed of protein fibers, which is closely related to cell movement, division, differentiation, material transportation, energy conversion, information transmission and other life activities.
The cytoskeleton supports organelles such as the endoplasmic reticulum and mitochondria, while free ribosomes are suspended at the intersections of the micronetwork.
Function
It is the main place where living cells carry out metabolism, providing the necessary substances for metabolism.
Provide a stable microenvironment for cell organelles
Affects cell shape
Can carry out a variety of chemical reactions
organelles
Separation method
Differential centrifugation: The sedimentation rate depends on the mass, size and density of the particles. After the cell membrane is destroyed, a homogenate composed of various organelles and other substances in the tissue is formed. The homogenate is put into a centrifuge tube and centrifuged at different speeds with a high-speed centrifuge to separate the various organelles.
Centrifugal technology: When the biological sample suspension rotates at high speed, due to the huge centrifugal force, the suspended tiny particles, biological macromolecules, etc. settle at a certain speed, thereby being separated from the solution.
Division of labor
Mitochondria
Ingredients: Contains phospholipids, proteins, DNA, RNA Distribution: Except for special cells, all eukaryotic cells have Function: The main place of aerobic respiration, the power of cells, and workshop cells. About 95% of the energy required for life activities comes from mitochondria.
chloroplast
Ingredients: Phospholipids, proteins, DNA, RNA Distribution: Plant mesophyll cells, etc. Function: The cells of green plants that perform photosynthesis contain organelles that are the "nutrient manufacturing workshops" and "energy conversion stations" of plant cells.
endoplasmic reticulum
Ingredients: Phospholipids, proteins Distribution: Both animals and plants
Rough endoplasmic reticulum: protein processing Smooth endoplasmic reticulum: the “workshop” of lipid synthesis. For example: can synthesize sex hormones
golgi apparatus
Ingredients: Phospholipids, proteins Distribution: Both animals and plants Function: "Workshop" and "Sending Station" for processing, classifying, and packaging proteins from the endoplasmic reticulum
The central body
Ingredients: protein Distribution: animals and some lower plants Function: Related to cell mitosis, usually replicates during interphase, enters the cell poles during division, emits new rays, and forms the spindle
Ribosome
Ingredients: protein, RNA Distribution: Found in both eukaryotic and prokaryotic cells, it is the most widely distributed organelle Function: A protein-producing machine, in which free ribosomes synthesize intracellular proteins and attached ribosomes synthesize secreted proteins
vacuole
Ingredients: single-layer membrane, containing phospholipids, cell fluid containing sugars, inorganic salts, pigments, proteins and other substances Distribution: Mature plant cells Function: Regulates the environment within plant cells. Filled vacuoles can also keep plant cells strong.
lysosome
Ingredients: phospholipids, proteins, containing a variety of hydrolases Distribution: Both animals and plants Function: It is a "digestion workshop" that decomposes aging and damaged organelles, engulfs and kills viruses and germs that invade cells; the products decomposed by lysosomes, if they are useful substances for cells, can be reused by cells, while waste is recycled Expelled from cells
Structural supplement
Chloroplasts and mitochondria both contain DNA and RNA molecules, as well as ribosomes, which can be transcribed and translated; they synthesize proteins to control some of their own traits. These two organelles are also called "semi-autonomous organelles."
Chloroplasts and mitochondria increase membrane area in different ways: The inner mitochondrial membrane folds inward to form cristae, which increases the membrane area, thus increasing attachment sites for enzymes and promoting aerobic respiration. The chloroplast grana is composed of stacked endocysts, which increases the membrane area. It also has a large number of pigments and enzymes that can carry out the light reactions of photosynthesis.
The structure and function of cells are adapted to different functions. Cells with different functions have different structural characteristics. For example: cells with strong protein synthesis have more ribosomes. In addition, the nucleoli in the nucleus are larger and there are more nuclear pores; mesophyll cells contain a large number of chloroplasts, but root cells do not contain chloroplasts; cells with strong metabolism In cells, there are many mitochondria; there is only one organelle in prokaryotic cells, namely ribosomes
Rough endoplasmic reticulum and smooth endoplasmic reticulum have different functions. Rough endoplasmic reticulum processes proteins, while smooth endoplasmic reticulum processes lipids.
Proteins synthesized by ribosomes attached to the endoplasmic reticulum are processed by the attached endoplasmic reticulum to form secreted proteins Proteins synthesized by free ribosomes will form intracellular proteins without being processed by the endoplasmic reticulum.
In addition to the functions of processing, classifying, and packaging proteins, the Golgi apparatus also has the following functions in different cells: 1. Cell walls are formed during plant division. 2. Formation of synaptic vesicles on the presynaptic membrane of nerve cells 3. Formation of lysosomes 4. The acrosome is formed during sperm deformation.
Pigments in plant cells (the two have different properties and completely different functions) 1. The pigments in chloroplasts are called "photosynthetic pigments" and are distributed on the thylakoid film, including chlorophyll a, chlorophyll b, carotene and lutein. They are fat-soluble pigments and are extracted by organic solvents. 2. The pigment in the vacuole is "anthocyanin", which is a water-soluble pigment
biofilm system
system
Cell model: single layer, the outer membrane of the cell
Nuclear membrane: double layer, with nuclear pores, the outer membrane of the nucleus
organelle membrane
Double membrane: chloroplast, mitochondria
Intralipid membrane: endoplasmic reticulum, Golgi apparatus, vacuoles, lysosomes, etc.
Prokaryotes only have cell membranes and cannot form a biofilm system
Unique component of animal cell membranes: cholesterol
Function
cell membrane
Provide cells with a relatively stable internal environment
Determines material transport, energy conversion and information transfer between cells and the external environment
other cell membranes
Enzyme attachment site → function → creates conditions for a variety of chemical reactions to proceed
Regionalize the interior of cells → function → ensure efficient and orderly progress of cell life activities
Concept and research methods of secreted proteins
Secreted proteins: refers to proteins that are synthesized in cells and then secreted to work outside the cells. Commonly considered secreted proteins include: antibodies, digestive enzymes, insulin, protein hormones, etc.
Intracellular proteins: proteins that remain in the cell to function after being synthesized in the cell, including: respiratory enzymes, hemoglobin, etc.
isotope labeling
Also known as the isotope tracing method, it is a method that uses isotope atoms to study the process of organic reactions.
Commonly used isotopes include: ¹⁴C (¹²C), ³H (¹H), ¹⁸O (¹⁶O), ¹⁵N (¹⁴N), ³²P (³¹P), ³⁵S (³²S)
Isotopic labeling to study the synthesis and processing of secreted proteins as the picture shows
The connections between biofilms
Component connection: The components of each biofilm are basically similar, consisting of lipids, proteins and a small amount of sugars, reflecting the unity of the biofilm system; however, the proportion of each component in various biofilms is different, reflecting Differences in biofilms
Structural connection: the endoplasmic reticulum membrane is directly connected to the cell membrane and the outer membrane of the mitochondria; during the processing and secretion of secreted proteins, the endoplasmic reticulum membrane is indirectly connected to the Golgi membrane and the cell membrane through vesicles, and biological membranes can transform into each other. , this is because the composition and structure of various membranes are basically the same. In the process of indirect transformation, the Golgi apparatus is the "hub" of transformation.
cell nucleus
structure
Nuclear membrane: a double membrane that separates the contents of the nucleus from the cytoplasm
Chromatin: Mainly composed of DNA and protein, DNA is the carrier of genetic information
Nuclear pore: related to the synthesis of certain RNA (i.e. tRNA) and the formation of ribosomes
Nuclear pore: enables frequent material exchange and information exchange between the nucleus and the cytoplasm (DNA cannot pass through the nuclear pore, but RNA can) The proteins surrounding the nuclear pore that control the entry and exit of materials are selective and do not control entry or exit based only on the size of the molecule.
Note: Cells with strong metabolism will have larger and more nucleoli. The number of membrane layers transported through the nuclear pore is 0
experiment
Nuclear transplantation of two axolotl cells
Experimental conclusion: The inheritance of skin color is controlled by the cell nucleus
Experimental analysis: no control group
Fertilized eggs of the hanged salamander
Experimental conclusion: Salamander cell division and differentiation are controlled by the nucleus
Experimental analysis: both mutual control and self-control
amoeba cutting
Experimental conclusion: The division, growth, regeneration and stress of amoeba are controlled by the cell nucleus
Experimental analysis: both mutual control and self-control
Umbrella grafting and nuclear transfer
Experimental conclusion: The shape of the umbrella algae "cap" is controlled by the cell nucleus
Experimental analysis: There are mutual controls in the Umbrella grafting experiments, but it cannot prove that the cell nuclei in the rhizoids determine their properties; the nuclear transplantation experiment can eliminate the influence of other substances in the rhizomes, thereby proving the experimental conclusions.
Function
The nucleus is the genetic information repository and the main place where genetic material is stored and replicated.
The nucleus is the control center of cell metabolism and genetics
other
The nucleus is the most important part of the cell structure. Cells without a nucleus can neither grow nor divide.
Both nuclear molds and nuclear pores are selectively permeable. Although nuclear pores allow large molecules to pass through, they are still selective
The nucleolus is not a storage site for genetic material
Chromatin is an extremely fine filament, formed by the tight combination of DNA and histones. It is named because it is easily stained darkly by basic dyes. During cell division, the cell nucleus disintegrates, and the chromatin filaments are highly spiralized, shortened and thickened, and become cylindrical or rod-shaped chromosomes clearly visible under a light microscope. At the end of cell division, the chromosomes unwind and reform into thin filaments of chromatin that are enclosed in the newly formed nucleus. Chromatin and chromosomes are two states of the same substance in cells at different stages.