Wondershare EdrawMind
MindMap Gallery Biology Compulsory 1 Molecules and Cells
- 138
Biology Compulsory 1 Molecules and Cells
This is a mind map about molecules and cells in Biology Compulsory Course 1, which summarizes the introduction to cells, the molecules that make up cells, the basic structure of cells, and the material input and output of cells.
Edited at 2024-02-03 13:57:01
- What is a Limit
Explore the fascinating world of limits, a fundamental concept in calculus that underpins derivatives and integrals. This overview delves into the core idea of limits, emphasizing how they describe the value a function approaches as the input nears a certain point. Learn about intuitive understandings through approaches versus equals, and the formal ε–δ definition that rigorously defines limits. Discover various types of limits, including one-sided and limits at infinity, and when limits exist or fail. Uncover key properties, their relationship to continuity, and techniques for evaluating limits. Join us in mastering the foundational concepts that shape mathematical analysis!
- Work and Power
Explore the fundamental concepts of work and power, essential for understanding energy dynamics in physics. This overview covers core definitions, including work as energy transfer and power as the rate of work done. Delve into the work-energy relation, examining the work-kinetic energy theorem and the distinctions between conservative and nonconservative forces. Learn how to calculate work under various conditions, from constant forces to variable forces and multiple interactions. The mechanical energy framework explains energy conservation principles, while power calculations provide insight into energy transfer rates. Utilize graphical tools and diagrams to visualize these concepts, avoiding common pitfalls in understanding work and its implications.
- What are Isotopes
Discover the fascinating world of isotopes, the variants of chemical elements that share the same number of protons but differ in neutrons, leading to unique properties. This overview covers the core definitions and atomic structure basics of isotopes, including their notation and abundance. Learn about examples like hydrogen, carbon, and oxygen, and differentiate between stable isotopes and radioisotopes. Understand the significance of isotopic variation, its origins in stellar processes and fractionation, and how we measure isotopes using advanced techniques like mass spectrometry. Join us in exploring the critical role isotopes play in science and nature.
Biology Compulsory 1 Molecules and Cells
- What is a Limit
Explore the fascinating world of limits, a fundamental concept in calculus that underpins derivatives and integrals. This overview delves into the core idea of limits, emphasizing how they describe the value a function approaches as the input nears a certain point. Learn about intuitive understandings through approaches versus equals, and the formal ε–δ definition that rigorously defines limits. Discover various types of limits, including one-sided and limits at infinity, and when limits exist or fail. Uncover key properties, their relationship to continuity, and techniques for evaluating limits. Join us in mastering the foundational concepts that shape mathematical analysis!
- Work and Power
Explore the fundamental concepts of work and power, essential for understanding energy dynamics in physics. This overview covers core definitions, including work as energy transfer and power as the rate of work done. Delve into the work-energy relation, examining the work-kinetic energy theorem and the distinctions between conservative and nonconservative forces. Learn how to calculate work under various conditions, from constant forces to variable forces and multiple interactions. The mechanical energy framework explains energy conservation principles, while power calculations provide insight into energy transfer rates. Utilize graphical tools and diagrams to visualize these concepts, avoiding common pitfalls in understanding work and its implications.
- What are Isotopes
Discover the fascinating world of isotopes, the variants of chemical elements that share the same number of protons but differ in neutrons, leading to unique properties. This overview covers the core definitions and atomic structure basics of isotopes, including their notation and abundance. Learn about examples like hydrogen, carbon, and oxygen, and differentiate between stable isotopes and radioisotopes. Understand the significance of isotopic variation, its origins in stellar processes and fractionation, and how we measure isotopes using advanced techniques like mass spectrometry. Join us in exploring the critical role isotopes play in science and nature.
- Recommended to you
- Outline
Biology Compulsory 1 Molecules and Cells
Chapter 1 Entering the cell
Section 1 Cells are the basic units of life activities
Cell theory and its establishment process
Founder: Schleiden, Schwann
Main takeaways:
1. A cell is an organism. All animals and plants develop from cells and are composed of cells and cell products;
2. A cell is a relatively independent unit, which not only has its own life, but also contributes to the overall life composed of other cells;
3. New cells are produced by the division of old cells.
significance:
1. The cell theory reveals the unity of animals and plants, thereby clarifying the unity of the biological world;
2. The cell theory made people realize that plants and cells have a common structural basis, thus breaking the long-standing ideological barrier between botany and zoology;
3. Promote the long-accumulated disciplines of anatomy, biology, embryology and other disciplines to gain a common foundation. The integration and unification of these disciplines gave birth to the birth of biology;
4. The conclusion that cell division produces new cells in the cell theory not only explains ontogeny, but also paved the way for the later establishment of the theory of biological evolution.
Cells are the basic system of life
Population: a group of all individuals of the same species within a certain spatial range;
Community: a larger whole formed by the interaction of different populations;
Ecosystem: The larger whole formed by the interaction of communities and the inorganic environment;
Biosphere: The greater whole in which all ecosystems on Earth are interconnected.
Section 2 Diversity and Unity of Cells
Observe cells
① Rotate the reflector to make the field of vision brighter;
② After observing clearly under low magnification, move the object image to be magnified and observed to the center of the field of view;
③ Turn the converter to change to a high-magnification objective lens;
④Use the fine focusing screw to adjust the focus and observe.
Prokaryotic cells and eukaryotic cells
Concept: Scientists divide cells into two categories: eukaryotic cells and prokaryotic cells based on whether there is a nucleus bounded by the nuclear membrane.
Eukaryotes: Organisms composed of eukaryotic cells are called eukaryotes, such as plants, animals, fungi, etc.
Prokaryotes: Organisms made of prokaryotic cells are called prokaryotes.
The main difference: whether there is a nucleus bounded by the nuclear membrane
Nucleoid: There is no nucleus surrounded by a nuclear membrane and no chromosomes, but there are circular DNA molecules located in a specific area within the cell. This area is called nucleoid.
Cyanobacteria cells: contain phycocyanin and chlorophyll in their bodies and are autotrophs capable of photosynthesis.
Chapter 2 Molecules that make up cells
Section 1 Elements and Compounds in Cells
elements that make up cells
Massive elements: C, H, O, N, P, S, K, Ca, Mg, etc.
Trace elements: Fe, Mn, Zn, Cu, B, Mo, etc.
The most basic element: C
Basic elements: C, H, O, N
Main elements: C, H, O, N, P, S
Source of elements: selectively absorbed from inorganic nature
compounds that make up cells
compound
Inorganic compounds: water (85% ~ 90%), inorganic salts (1% ~ 1.5%)
Organic compounds: protein (7% ~ 10%), lipid (1% ~ 2%),...
The compound that accounts for most of the cell's fresh weight is water;
The organic matter that accounts for the most fresh weight of cells is protein;
The compounds that account for the largest amount of cell dry weight are proteins;
Fresh weight-H₂O=dry weight
Main compounds that make up cells
Water (70% to 90%), protein (7% to 10%), lipid (1% to 2%), inorganic salts (1% to 1.5%), sugars and nucleic acids (1% to 1.5%)
Carbohydrates, fats and proteins in biological tissues
Fehling's reagent reacts with reducing sugar to produce brick red color
Fat is stained orange with Sudan 3 dye
Biuret reagent reacts with protein and turns purple
Section 2 Inorganic substances in cells
water in cells
Moisture content of organisms: The moisture content of organisms varies with different species of organisms, generally ranging from 60% to 95%. The water content of jellyfish reaches 97%.
The meaning of water: Water is an important component of cells and the most abundant compound in living cells.
water form
Free water: Most of the water is in a free state and can flow freely, which is called free water;
Free water is a good solvent within cells;
The greater the proportion of free water in the cell, the more vigorous the metabolism of the cell.
Bound water: Part of the water combined with other substances in the cell is called bound water;
Bound water is an important component of cell structure;
The greater the proportion of bound water in a cell, the stronger the cell's ability to withstand adverse environments such as drought and cold.
Free water and bound water can be converted into each other
Free water can be converted into bound water by cooling;
Bound water can be converted into free water by heating.
inorganic salts in cells
Most inorganic salts in cells exist in the form of ions
Cations with higher content: Na⁺, K⁺, Ca⁺, Mg²⁺, Fe²⁺, Fe³⁺, etc.
Anions with higher content: Cl⁻, SO₄³⁻, HCO₃⁻, etc.
Certain inorganic salt ions in living organisms must be maintained in a certain amount, which is very important for maintaining the acid-base balance (osmotic pressure) of cells
Many kinds of inorganic salts play an important role in maintaining the life activities of cells and organisms.
Section 3 Carbohydrates and Lipids in Cells
Sugar is the main energy substance
Sugar molecules are generally composed of three elements: C, H, and O
In most sugar molecules, the ratio of hydrogen atoms to oxygen atoms is 2:1, similar to water molecules, so sugars are also called "carbohydrates", abbreviated as (CH₂O)
Monosaccharide
Glucose (C₆H₁₂O₆);
Glucose is the main energy substance required for cell life activities and is often described as the "fuel of life";
Sugars that cannot be hydrolyzed are monosaccharides, common monosaccharides include fructose, galactose, ribose, deoxyribose, etc.
Disaccharide (C₁₂H₂₂O₁₁)
Disaccharides are formed by the dehydration and condensation of two molecules of monosaccharides, and generally need to be hydrolyzed into monosaccharides before they can be absorbed by cells;
The most common disaccharides in life are sucrose, brown sugar, white sugar, rock sugar, etc.;
Sucrose is abundant in sugar cane and sugar beets, and is also found in most fruits and vegetables.
Polysaccharide [(C₆H₁₀O₅)]
Most sugars in living organisms exist in the form of polysaccharides;
Starch is the most common polysaccharide;
Starch ingested by the human body must be digested and broken down into glucose before it can be absorbed and utilized by cells;
Starch is abundantly found in the abnormal stems or roots of potatoes, yams, sweet potatoes and other plants, as well as in the fruits of some plants;
It is also found in large amounts in the seeds of food crops, corn, wheat, and rice.
cellulose
It is also a polysaccharide, insoluble in water and difficult to digest. Its basic unit is also a glucose molecule.
Chitin
Chitin is also a polysaccharide, also known as chitin;
Widely found in the exoskeletons of crustaceans and insects;
Chitin is widely used in medicine, chemical industry, etc.
lipids in cells
Chemical elements that make up lipids: C, H, O (some paper also contains P and N)
Unlike sugars, the oxygen content in lipid molecules is much lower than that of sugars, while the hydrogen content is higher;
Common lipids: fats, phospholipids and sterols, etc.;
Their molecular structures are very different, and they are usually insoluble in water, but soluble in fat-soluble organic solvents, such as acetone, chloroform, ether, etc.;
Fat is the most common lipid;
Fat is an ester formed by the reaction of three molecules of fatty acids with one molecule of glycerol, namely triacylglycerol (also known as triglyceride);
Fat is a good energy storage material in cells
Phospholipids
The difference from fat is that one of the hydroxyl groups (-OH) of glycerol is not combined with fatty acids to form fat, but with phosphoric acid and other derivatives;
In addition to C, H, and O, phospholipids also contain P and even N;
Phospholipids are an important component of cell membranes and the membranes of various organelles.
sterol
Sterols include cholesterol, sex hormones, vitamin D, etc.;
Cholesterol is an important component of animal cell membranes and is also involved in the transport of lipids in the blood in the human body;
Sex hormones can promote the development of human and animal reproductive organs and the formation of germ cells;
Vitamin D can effectively promote the intestinal absorption of calcium and phosphorus in humans and animals.
Sugars and lipids in cells can be converted into each other
Section 4 Protein is the main carrier of life activities
Protein is the main carrier of life activities
protein function
Many proteins are important substances that make up the structure of cells and organisms, called structural proteins;
Some proteins can regulate the body's life activities, such as insulin and growth hormone;
Chemical reactions in cells are inseparable from the catalysis of enzymes, and most enzymes are proteins;
Some proteins have transport functions;
Some proteins have immune functions. Antibodies in the human body are proteins that can help the body resist antigens such as bacteria and viruses;
Generally speaking, proteins are the basic components of cells and have important functions such as participating in cell structure, catalytic transport, information transmission, and immunity;
All life activities of cells are inseparable from proteins;
The fact that proteins can undertake so many functions is related to the diversity of proteins;
The basic building blocks of protein – amino acids
There are 21 types of amino acids that make up proteins;
Amino acids are the basic units that make up proteins;
Each amino acid contains at least one amino group and one carboxyl group, and both have an amino group and a carboxyl group connected in the same Taiyuan. Each amino acid contains at least one amino group (-NH₂) and one carboxyl group (-COOH), and both have an amino group. attached to the same carbon atom as a carboxyl group;
This carbon atom is also connected to an oxygen atom and a side chain group. This testing group is represented by R;
The difference between various amino acids lies in the difference in the R group;
Lysine, tryptophan, phenylalanine, methionine, threonine, isoleucine, leucine, and valine are eight amino acids that cannot be synthesized by the human body. This type of amino acid is called For essential amino acids. The other 13 amino acids can be synthesized by the human body and are called non-essential amino acids;
Although the types of amino acids are limited, they constitute a wide variety of proteins with diverse functions
Protein structure and its diversity
Protein is a biological macromolecule composed of amino acids as basic units
Amino acid molecules are first connected by mutual binding: the carboxyl group (-COOH) of one amino acid molecule is connected to the amino group (-NH₂) of another amino acid molecule, and a molecule of water is removed at the same time. This combination method is called dehydration condensation;
The chemical bond that connects two amino acid molecules is called a peptide bond, and the compound formed by the condensation of two amino acids is called a dipeptide;
Compounds formed by the condensation of multiple amino acids and containing multiple peptide bonds are called polypeptides;
Polypeptides usually take the form of cushion-like structures called peptide chains.
binding process
Dehydration and condensation between amino acids form peptide chains;
Specific regions of a peptide chain undergo regular coiling and folding;
This peptide chain is further coiled to form a certain spatial structure;
Four peptide chains come together to form a complex spatial structure.
Number of peptide bonds formed = number of amino acids - number of peptide chains = number of water molecules removed
There are different types of amino acids, different amounts, and the order of arrangement is also ever-changing. This is the reason why there are so many types of proteins in cells.
Section 5 Nucleic acid is the carrier of genetic information
Types of nucleic acids and their distribution
One type is deoxyribonucleic acid, referred to as DNA; the other type is ribonucleic acid, referred to as RNA;
The DNA of eukaryotic cells is mainly distributed in the nucleus, mitochondria, and chloroplasts also contain a small amount of DNA;
RNA is mainly distributed in the cytoplasm.
Nucleic acids are long chains of linked nucleotides
Nucleotides are the basic building blocks of nucleic acids;
A nucleotide is composed of a nitrogen-containing base molecule, a five-carbon sugar molecule, and a phosphate molecule;
According to the different five-carbon sugars, nucleotides can be divided into deoxyribonucleotides (referred to as deoxyribonucleotides) and ribonucleotides;
DNA is a long chain made of deoxynucleotides linked together, and RNA is a long chain made of ribonucleotides linked together;
Generally, in the cells of organisms, DNA is composed of two deoxynucleotide strands, and RNA is composed of a ribonucleotide strand;
The sequence of deoxyribonucleotides stores the genetic information of organisms, and DNA molecules are organisms that store and transmit genetic information. The genetic information of most viruses is stored in RNA;
Nucleic acids are substances that carry genetic information in cells and play an extremely important role in genetic variation and protein biosynthesis of organisms;
Biological macromolecules use carbon chains as skeletons
The basic unit of protein is amino acid, and the basic unit of amino acid is nucleotide. These basic units are called monomers;
Each monomer has a carbon chain composed of several connected carbon atoms as the basic skeleton. Biological macromolecules are polymers connected by many monomers, so biological macromolecules also use carbon chains as the basic skeleton;
"Carbon is the core element of life" "Without carbon, there would be no life."
Chapter 3 Basic Structure of Cells
Section 1 Structure and Function of Cell Membrane
function of cell membrane
Separate cells from the outside environment
Separating living matter from the external environment produced primitive cells and became relatively independent systems;
The cell membrane ensures the relative stability of the internal environment of the cell.
Controlling the movement of substances in and out of cells
Generally speaking, nutrients needed by cells can enter cells slowly, while substances that cells do not need cannot easily enter cells;
The control role of the cell membrane is relative.
exchange information between cells
Maintain the realization of functional coordination so that organisms can survive healthily;
Indirect communication: Hormones secreted by endocrine cells bind to receptors on the cell membrane surface of target cells and transmit information to target cells;
Direct communication: The cell membranes of two adjacent cells are in contact, and information is passed from one cell to another;
Information is transmitted by forming special channels: a channel is formed between two adjacent cells, and the material carrying information enters another cell through the channel (for example, higher plant cells are connected to each other through plasmodesmata, which also plays a role in information exchange)
Exploring the structure of cell membranes
Cell membranes are mainly composed of lipids and proteins
Among them, paper accounts for about 50% of the total mass of the cell membrane, protein accounts for about 40%, and sugars account for 2% to 10%;
Among the lipids that make up cell membranes, phospholipids are the most abundant, and there is also a small amount of cholesterol.
The more complex the function of the cell membrane, the greater the number and type of proteins.
The cell membrane is fluid
Basic contents of flow mosaic model
Cell membranes are mainly composed of phospholipid molecules and protein molecules;
The phospholipid bilayer is the basic component of the membrane, and its interior is the hydrophobic end of the phospholipid molecules, which has a barrier function ()
Protein molecules are embedded in the phospholipid bilayer in different ways
Some are embedded on the surface of the phospholipid bilayer;
Some are partially or completely embedded in the phospholipid bilayer;
Some penetrate the entire phospholipid bilayer
cell membrane fluidity
The phospholipid molecules that make up the membrane can move freely sideways. Most of the proteins in the membrane can also move.
Significance: The fluidity of cells is very important for cells to complete functions such as material transportation, growth, division, and movement.
(The outer surface of the cell membrane contains sugar molecules, which combine with protein molecules to form protein sugars or combine with lipids to form glycolipids. These sugar molecules are called sugar coats, and they are recognized by the cell surface, transmit information between cells, etc. functions are closely related)
Section 2 Division of labor and cooperation among cell organelles
Organelles are distributed in the cytoplasmic matrix
division of labor between cells
Cell wall: The cell wall is located outside the cell membrane of plant cells and is mainly composed of cellulose and pectin. It supports and protects the cells;
Vacuoles: Vacuoles mainly exist in plant cells. They contain cell fluid, containing sugars, inorganic salts, pigments, and proteins. They can regulate the environment within plant cells. Filled vacuoles can also keep plant cells strong;
Chloroplast: Chloroplast is an organelle in the cells of green plants that can carry out photosynthesis. It is the "nutrient manufacturing workshop" and "energy conversion station" of plant cells;
Lysosome: Lysosome is mainly distributed in animal cells and is the "digestion workshop" of the cell. It contains a variety of hydrolytic enzymes inside, which can decompose aging and damaged organelles, phagocytose and kill viruses or bacteria that invade the cell;
Centrosome: Centrosome is distributed in animal and lower plant cells. It consists of two mutually perpendicularly arranged centers and surrounding materials. It is related to cell mitosis.
Ribosomes: Some ribosomes are abundant in the rough endoplasmic reticulum, and some are free in the cytoplasmic matrix and are "machines for producing proteins";
Endoplasmic reticulum: The endoplasmic reticulum is the synthesis, processing site and transportation channel for macromolecules such as proteins. It is connected by tubular, vesicular or flat sac-like structures surrounded by membranes to form a continuous membranous duct system with interconnected lumens. . Some endoplasmic reticulum has ribosomes attached, which is called rough endoplasmic reticulum, and some endoplasmic reticulum does not contain ribosomes, which is called smooth endoplasmic reticulum;
Mitochondria: Mitochondria are the main place where cells carry out aerobic respiration and are the "power workshops" of cells. Approximately 95% of the energy required for cell life activities comes from mitochondria;
Golgi apparatus: The Golgi apparatus is mainly the "workshop" and "sending station" that processes, sorts, and packages proteins from the endoplasmic reticulum.
The organelles in the cytoplasm are not floating in the cytoplasm, but have a structure that supports them - the cytoskeleton.
The cytoskeleton is a network structure composed of protein fibers
effect
Maintain cell shape;
anchors and supports many organelles;
Closely related to cell movement, division, differentiation, material transportation, energy conversion, information transmission and other life activities;
Coordination between organelles
Secreted protein synthesis and transport
Some proteins are synthesized within cells and then secreted outside the cells to function. These proteins are called secreted proteins.
isotope labeling
In the same element, atoms with the same number of protons and different numbers of neutrons are isotopes;
Using isotopes with special physical properties to mark the whereabouts of atoms in chemical reactions is called isotope labeling.
Secretory protein synthesis
In free ribosomes, the synthesis of polypeptide chains begins with amino acids as raw materials;
Together with ribosomes, it is transferred to the rough endoplasmic reticulum to continue the synthesis process. While being synthesized, it is transferred to the endoplasmic reticulum cavity, and then processed and folded to form a protein with a certain spatial structure;
The endoplasmic reticulum membrane bulges to form vesicles, which wrap proteins and leave the endoplasmic reticulum to the Golgi, where the body fuses with the Golgi membrane. The vesicle membrane becomes part of the Golgi membrane;
The Golgi apparatus further modifies and processes the protein, and then the Golgi apparatus model horizontally wraps the protein vesicles;
The vesicles are transported to the cell membrane, fuse with the cell membrane, and secrete the protein out of the cell.
During the synthesis, processing and transportation of secreted proteins, energy is required, which mainly comes from mitochondria.
The Golgi apparatus plays an important role as a transportation hub
cell biofilm system
Organelle membranes, cell membranes, nuclear membranes and other structures together constitute the cell's biofilm system.
Biofilm systems play an important role in the life activities of cells
Provide cells with a relatively stable internal environment;
It plays a decisive role in the process of material transportation, energy conversion and information transmission between cells and the external environment;
Many important chemical reactions require the participation of enzymes, and the vast membrane area provides attachment points for a variety of enzymes;
The biofilm within the cell separates various organelles, allowing multiple chemical reactions to occur simultaneously within the cell without interfering with each other, ensuring the orderly conduct of cellular life activities.
Section 3 Structure and Function of Cell Nucleus
function of cell nucleus
The nucleus controls the metabolism and inheritance of the cell;
The nucleus is the "control center" of the cell.
structure of cell nucleus
Nuclear membrane: A double-layered membrane separates the inner material from the cytoplasm and transports small molecules;
Nucleolus: related to the synthesis of certain RNA and the formation of ribosomes;
Chromatin: Mainly composed of DNA and protein, DNA is the carrier of genetic information;
Nuclear pore: realizes frequent material exchange and information exchange between the nucleus and the cytoplasm, and transports macromolecules
morphology of chromosomes
During cell division, the nucleus disintegrates and the chromatin is highly spiralized, shortened and thickened, becoming cylindrical or rod-shaped chromosomes clearly visible under a light microscope;
At the end of cell division, the chromosomes unwind and re-form into filaments of chromatin that are enclosed in the newly formed nucleus.
Broken filamentous chromosomes are easier to replicate
Chromatin and chromosomes are the same material, two states of existence at different stages of the cell
The cell nucleus is the genetic information database and the control center of cell metabolism and genetics.
The interdependence of the nucleus and cytoplasm
Build model
type
Physical model (actual, in pictorial form, not photographic);
Conceptual model (mind map);
Mathematical model (formula)
Chapter 4 Material Input and Output of Cells
Section 1 Passive transportation
Osmosis
The diffusion of water molecules or other solvent molecules through a semipermeable membrane is called osmosis
Principle: If there is a concentration difference on both sides of the semi-permeable membrane, the direction of penetration is that water molecules penetrate from the side with a higher relative content of water to the side with a lower relative content.
conditions for osmosis to occur
with semipermeable membrane
The solution on both sides of the semipermeable membrane has a concentration difference
Hypotonic solution: When the concentration of the external solution is lower than the concentration of the cytoplasm, the cells absorb water and swell.
Hypertonic solution: When the concentration of the external solution is higher than the concentration of the cytoplasm, the cells lose water and shrink
Isotonic solution: When the concentration of the external solution is the same as that of the cytoplasm, the cell morphology remains unchanged.
Cells are fully permeable
protoplasm layer
The cell membrane, the tonoplast and the cytoplasm between the two membranes are called the protoplasm layer
The composition of the protoplasm layer
cell membrane
cytoplasm
tonoplast
The cell membrane is equivalent to a semipermeable membrane
There is a concentration difference between the cytoplasm within the cell membrane and the external solution
plasmolysis
Concept: Separation of protoplasm and cell wall
When the concentration of the cell fluid is less than the concentration of the external solution, the water in the cell fluid passes through the protoplasm layer and enters the external solution, causing both the cell wall and the protoplasm layer to shrink to a certain extent. When the cells continue to lose water, due to the ratio of the protoplasm layer The cell wall is highly stretchable, and the protoplasm layer will gradually separate from the cell wall.
When the concentration of the cell fluid is greater than the concentration of the external solution, the water in the external solution will enter the cell fluid through the protoplasm layer, and the entire protoplasm layer will slowly return to its original state, causing the plant cells to gradually undergo plasmolysis. recovery
Conditions for choosing chemical reagents
Non-toxic to cells
Appropriate concentration
The reason for using the outer skin of purple onions for experiments: there are large purple vacuoles for easy observation
The reason for not selecting epidermal cells within scales: the cell membrane is colorless and difficult to observe
Substances enter and exit by diffusion without consuming the energy released by chemical reactions in cells. This method of transporting substances across membranes is called passive transport.
free diffusion and assisted diffusion
The way substances enter and exit cells through simple diffusion is called free diffusion, also called simple diffusion
Transport proteins on building membranes, the way substances diffuse into and out of cells is called assisted diffusion
Section 2 Active transport and endocytosis
active transport
The transport of substances across membranes against concentration gradients requires the assistance of carrier proteins and the consumption of energy released by chemical reactions within cells. This method is called active transport
Endocytosis and exocytosis
process
When a cell takes in a macromolecule, it first binds to the protein on the membrane, causing this part of the cell membrane to invaginate and form a small vesicle that surrounds the macromolecule.
The small vesicles are separated from the cell membrane, form vesicles, and enter the interior of the cell. This phenomenon is called endocytosis.
Macromolecules that need to be excreted from the cell membrane first form vesicles in the cell, move to the cell membrane, fuse with the cell membrane, and expel the macromolecules out of the cell. This phenomenon is called exocytosis.
In the process of transporting substances across membranes, swallowing and swallowing are common phenomena, and they also need to consume the energy released by cellular respiration.
Chapter 5 Energy Supply and Utilization of Cells
Section 1 Enzymes that reduce the activation energy of chemical reactions
1 The role and nature of enzymes
There are many chemical reactions going on in cells every moment, collectively called cell metabolism.
environment inside and outside the cell
normal temperature
normal pressure
water soluble
The role of enzymes in cell metabolism
Control variables and design controlled experiments
The changing factors during the experiment are called variables
The factors that are artificially controlled in the treatment of experimental subjects are called independent variables
The variable that changes when the independent variable changes is called the dependent variable
There are also some variable factors that affect the experimental results during the experiment, called irrelevant variables.
A control group without any treatment is called a blank control
catalysis
The energy required to change a substance from its normal state to an active state prone to chemical reactions is called activation energy.
Compared with inorganic catalysts, enzymes can reduce activation energy more significantly and have higher catalytic efficiency.
2 Characteristics of enzymes
Enzymes are catalytic organic substances produced by living cells, most of which are proteases
chemical nature
Most enzymes are proteins, and a few enzymes are RNA
Principle of action
Reduce the activation energy of a chemical reaction
basic unit
Amino acids or ribonucleotides (ribozymes)
synthesis place
Ribosomes and Nucleus
After action
The amount and properties of the enzyme remain unchanged
place of action
inside and outside the cell
Enzymes are highly efficient
significance
Ensures the smooth progress of chemical reactions within cells
Enzymes are specific
Enzyme action conditions are milder
Chemical reactions catalyzed by enzymes generally occur under relatively mild conditions.
Too acidic, too alkaline or too high a temperature will destroy the spatial structure of the enzyme and permanently inactivate the enzyme.
At about 0 degrees Celsius, the activity of the enzyme is very low, but the spatial structure of the enzyme is stable. At a suitable temperature, the activity of the enzyme will increase (therefore, enzyme preparations are suitable for storage at low temperatures)
Section 2 Cell’s “Energy Currency” ATP
ATP is a high-energy phosphate compound
The structure of ATP molecule: A-P~P~P
A stands for adenosine
P stands for phosphate group
~ represents a special chemical bond
The process of ATP hydrolysis is the process of releasing energy. The energy released by hydrolysis of 1 molATP is as high as 30.54kJ
ATP and ADP can be converted into each other
After ATP is hydrolyzed, it is converted into a compound more stable than ATP - ADP (adenosine diphosphate)
If the detached phosphate group is not transferred to other molecules, it becomes free phosphate (represented by Pi).
Under the action of relevant enzymes, ADP can accept energy and combine with Pi to re-form ATP.
The mutual conversion of ATP and ADP occurs all the time and is in dynamic balance.
significance
The energy supply mechanism for the mutual conversion of ATP and ADP is the same in the cells of all organisms, which reflects the unity of the biological world.
ADP+Pi+energy→enzyme→ATP
ATP utilization
Used for substance synthesis (a+b→c)
Used for muscle contraction (motor protein → ATP → protein movement)
The carrier protein involved in the active transport of Ca²⁺ is an enzyme that catalyzes the hydrolysis of ATP.
Section 3 Principles and Applications of Cellular Respiration
cellular respiration
Cellular respiration can be divided into two types: aerobic respiration and anaerobic respiration.
aerobic respiration
Main location: mitochondria
Mitochondria have two inner and outer membranes. Some parts of the inner membrane fold toward the inner cavity of the mitochondria to form cristae. The cristae greatly increases the surface area of the inner membrane. The cristae is surrounded by a liquid matrix. The inner membrane of the mitochondria and the matrix contain many an enzyme involved in aerobic respiration
total reaction
C₆H₁₂O₆ 6H₂O 6O₂→Enzyme→6CO₂ 12H₂O Energy
The first stage
One molecule of glucose is decomposed into two molecules of pyruvate, producing a small amount of [H] and releasing a small amount of energy.
Does not require the participation of oxygen
performed in the cytoplasmic matrix
second stage
Pyruvate and water are completely decomposed into carbon dioxide and [H], and a small amount of energy is released
No direct involvement of oxygen is required
Performed in the mitochondrial matrix (requires the participation of water)
The third phase
The [H] produced in the above two stages undergoes a series of chemical reactions and combines with oxygen to form water, while releasing a large amount of energy.
No direct involvement of oxygen is required
Performed on the inner mitochondrial membrane
Aerobic respiration refers to the process in which cells, with the participation of oxygen, use the catalysis of various enzymes to completely oxidize and decompose organic matter such as glucose to produce carbon dioxide and water, release energy, and generate a large amount of ATP.
Features
Aerobic respiration process is gentle
The energy in organic matter is gradually released through a series of chemical reactions
A significant portion of this energy is stored in ATP
anaerobic respiration
Reaction formula
Generate lactic acid: C₆H₁₂O₆→Enzyme→2C₃H₆O₃ (lactic acid) A small amount of energy
Generate alcohol: C₆H₁₂O₆→Enzyme→2C₂H₅OH (alcohol) 2CO₂ A small amount of energy
The first stage
Identical to the first stage of aerobic respiration
second stage
Pyruvate is broken down into alcohol and carbon dioxide, or converted into lactic acid, catalyzed by enzymes (different from those that catalyze aerobic respiration)
Whether it is decomposed into alcohol and carbon dioxide, or converted into lactic acid for anaerobic respiration, only a small amount of energy is released in the first stage and a small amount of ATP is generated.
Most of the energy in the glucose molecule is stored in alcohol or lactic acid
concept
In the absence of oxygen, the process of incomplete decomposition of organic matter such as glucose to release a small amount of energy is called anaerobic respiration.
cellular respiration
Cellular respiration refers to the process in which organic matter undergoes a series of oxidative decomposition within cells to generate carbon dioxide or other products, release energy, and generate ATP.
Application of principles of cellular respiration
Making of steamed buns, bread, kimchi and many other traditional foods
Modern fermentation industry produces penicillin, MSG and other products
Promote the respiration of crop roots by improving oxygen supply to facilitate crop growth
Measures such as lowering temperature and reducing oxygen content weaken the respiration of fruits and vegetables and reduce the consumption of organic matter.
Section 4 Photosynthesis and Energy Conversion
pigments that capture light energy
Carotenoids (content about 1/4)
Carotene (orange)
Lutein (yellow)
Mainly absorbs blue-violet light
Chlorophyll (content about 3/4)
Chlorophyll a (blue-green)
Chlorophyll b (yellow-green)
Mainly absorbs blue-violet and red light
The structure of chloroplasts is suitable for photosynthesis
Characteristics of chloroplasts
Chloroplasts are surrounded by a double membrane and contain many grana particles inside.
Each grana is made up of stacked disk-shaped cyst-like structures called thylakoids.
The four pigments that absorb light energy are distributed on the thin film of the thylakoids.
The spaces between grana particles are filled with matrix
principles of photosynthesis
concept
Photosynthesis refers to the process in which green plants use light energy to convert carbon dioxide and water into organic matter that stores positive energy through chloroplasts, and releases oxygen.
Reaction formula
CO₂ H₂O→Light Energy Chloroplast→(CH₂O) O₂
Where (CH₂O) represents sugar
light reaction stage
concept
The chemical reaction in the first stage of photosynthesis requires light to proceed. This stage is called the photoreaction stage.
Detailed explanation of light reaction process
NADP⁺＋H⁺＋2e⁺→NADPH
★H₂O→Light→1/2O₂↑＋NADPH
★ADP Pi Energy→ATP
Reaction site: thylakoid membrane
dark reaction stage
concept
The chemical reactions in the second stage of photosynthesis can proceed with or without light. This stage is called the dark reaction stage.
Application of the principles of photosynthesis
intensity of photosynthesis
Refers to the amount of sugar produced by plants through photosynthesis per unit time.
total reaction
CO₂ H₂O→Light Energy Chloroplast→(CH₂O) O₂
raw materials for photosynthesis
water
CO₂
The power of photosynthesis
light energy
photosynthesis rate = respiration rate
Influencing factors (internal factors)
Type and quantity of enzymes
Pigment content
Differences in leaf age
Chapter 6 The Life Course of Cells
Section 1 Cell Proliferation
Cell Proliferation
concept
The process by which cells increase their number through cell division is called cell proliferation
significance
Cell proliferation is an important cellular life activity and is the basis for growth, development, reproduction, and inheritance of organisms.
cell cycle
concept
For cells that divide continuously, one cell cycle begins when one division is completed and ends when the next division is completed.
Classification
interphase
division period
Early stage
medium term
later stage
Late period
Mitosis
concept
Mitosis is a continuous process. People divide them into four phases based on the behavior of chromosomes: prophase, metaphase, and anaphase.
process
interphase
Active material preparation is carried out for the division period, the replication of DNA molecules and the synthesis of related proteins are completed. At the same time, the cells have moderate growth. After the end of the division period, mitosis begins.
Features
The replication of DNA molecules and the synthesis of related proteins are completed
Cells have moderate growth
Early stage
Chromatin filaments are spirally wound, shortened and thickened to form chromosomes. Each chromosome consists of two side-by-side sister chromatids, which are connected by a common centromere.
Features
The nucleolus gradually disintegrates and the nuclear membrane gradually disappears
Spindle fibers emanate from the poles of the cell to form a spindle
Chromosomes are scattered in the center of the spindle
medium term
There are spindle fibers on both sides of the centromere of each chromosome. The spindle fibers pull the chromosomes to move so that the centromere of each chromosome is arranged on a plane in the center of the cell. This plane is consistent with the central axis of the spindle. Perpendicular to each other, similar to the position of the equator on the Earth, it is called the equatorial plate
Features
The chromosomes are fixed and the number is clear
The centromeres of chromosomes are arranged on the equatorial plate. This is the best time to observe chromosomes.
later stage
Each centromere splits into two sister chromosomes, and the monomer separates into two chromosomes, which are pulled by spindle fibers and move toward the two poles of the cell. As a result, there is a set of chromosomes at each pole of the cell. The shape and number of these two sets of chromosomes are exactly the same, and each set of chromosomes has the same shape and number as the chromosomes in the parent cell before division.
Features
The centromere divides into two sister chromosomes, and the monomer separates into two daughter chromosomes
The chromosomes are divided equally into two groups and move from the cell to the poles
Late period
When the two sets of chromosomes reach the two poles of the cell, each chromosome gradually turns into a long, slender and coiled chromatin filament. At the same time, the spindle fibers gradually disappear, a new nuclear membrane and nucleolus appear, and two new nuclei are formed. At this time, a cell plate appears at the equatorial plate, and the cell plate gradually expands to form a new cell wall.
Features
Each chromosome gradually becomes a long, coiled chromatin filament
The spindle fibers gradually disappeared, and new nuclear membranes and nucleoli appeared, forming two new nuclei.
A cell plate appears at the equatorial plate, and the cell plate gradually expands to form a new cell wall.
The difference between animal cell and plant cell division
Centrosome duplication in animal cells
The centrosomes of animal cells emit a large number of radiating star rays, and the star rays between the two sets of centrioles form the spindle.
At the end of animal cell division, no cell plate is formed. Instead, the cell membrane dents inward from the middle of the cell, and finally the cell is split into two parts.
The importance of mitosis
After the chromosomes of the young generation cells are replicated (the key is DNA replication), they are accurately divided into two daughter cells. Because there is genetic material DNA on the chromosomes, genetic stability is maintained between the parents and offspring of the cell.
Section 2 Cell Differentiation
concept
In ontogeny, the process in which the offspring produced by the proliferation of one or a kind of cell has stable differences in morphology, structure and physiological function is called cell differentiation.
Cell differentiation is the result of the selective expression of genes in cells, that is, during the process of individual development, the expression of genetic information is different in different types of cells.
The essence of cell differentiation
root cause
selective expression of genes
direct cause
Different types of proteins
Characteristics of cell differentiation
persistence
stability
irreversibility
The role of cell differentiation
Cell differentiation leads to the specialization of cells in multicellular organisms, which is beneficial to improving the efficiency of various physiological functions of the organism.
cell totipotency
concept
Totipotency of cells means that after cells divide and differentiate, they still have the potential and characteristics to produce a complete organism or differentiate into various other cells.
The higher the degree of differentiation, the weaker the totipotency
Section 3 Cell Aging and Death
Characteristics of cellular senescence
Changes in cell membrane permeability reduce material transport function
The water in the cells decreases, the cells shrink and become smaller in size
The activity of various enzymes in cells decreases, the respiration rate slows down, and the metabolism rate slows down
Pigments gradually accumulate in cells, hindering the communication and delivery of intracellular substances.
The area of the cell nucleus increases, the nuclear membrane folds in, the chromatin shrinks, and the staining deepens
Causes of cellular senescence
free radical theory
content
Abnormally active charged molecules or groups are usually called free radicals
Free radicals contain unpaired electrons and are highly reactive.
Free radicals attack and damage various biological molecules within cells that carry out normal functions.
In addition, free radicals can also attack DNA and may cause genetic mutations.
Attack proteins, causing protein activity to decrease, leading to cell aging
telomere theory
content
Each chromosome has a special sequence of DNA-protein complexes called telomeres at both ends.
Telomere DNA sequences shorten after each cell division
As the number of cell divisions increases, the truncated portion will gradually extend inward.
After the telomere DNA sequence is "truncated", the DNA sequence of the normal genes inside the telomere will be damaged, resulting in abnormal cell activities.
The relationship between cellular senescence and individual aging
For single cell organisms
The aging or death of cells is the aging or death of individuals
for multicellular organisms
Cellular aging and death are not the same thing as individual aging and death
As we age, the number of times cells continue to divide will gradually decrease, which means that cells will age as the number of divisions increases.
cell death
apoptosis
A major way of cell death
concept
The genetically determined process by which cells automatically end their lives is called apoptosis.
(Because apoptosis is strictly programmed and regulated by genetic mechanisms, it is a type of programmed death)
effect
Apoptosis plays a very critical role in the normal development of multicellular organisms, maintaining the stability of the internal environment and resisting interference from various external factors.
Necrosis
concept
Cell necrosis refers to cell damage and death caused by damage or interruption of normal metabolic activities of cells under the influence of various adverse factors, such as extreme physical and chemical factors or severe pathological stimulation.
autophagy
concept
Autophagy is when cells eat their own structures and substances