The first chapter close to the cell

Section 1 From Biosphere to Cell

First, related concepts,

Fine cell: the basic unit of organism structure and function. All living things are made up of cells except viruses. Cells are the most basic life system on earth.

The structural level of life system: cells → tissues → organs → systems (plants have no systems) → individuals → groups.

→ Community → Ecosystem → Biosphere

Second, the virus related knowledge:

1, virus is a kind of organism without cell structure. Main features:

① The individual is tiny, generally between 10~30nm, and most of them can only be seen with an electron microscope;

There is only one kind of nucleic acid, DNA or RNA, and there is no virus containing two kinds of nucleic acids;

3. Specializing in intracellular parasitic life;

④ Simple structure, generally consisting of nucleic acid (DNA or RNA) and protein shell.

2. According to different parasitic hosts, viruses can be divided into three categories: animal viruses, plant viruses and bacterial viruses (phages). According to the different kinds of nucleic acids contained in viruses, they can be divided into DNA viruses and RNA viruses.

3. Common viruses are: human influenza virus (causing influenza), SARS virus, human immunodeficiency virus (HIV)[ causing AIDS], avian influenza virus, hepatitis B virus, human smallpox virus, rabies virus, tobacco mosaic virus, etc.

Section 2 Diversity and Unity of Cells

1. Cell type: Cells are divided into prokaryotic cells and eukaryotic cells according to whether they have nuclei or not.

Second, the comparison between prokaryotic cells and eukaryotic cells:

1. Prokaryotic cells: small cells, nuclear-free membranes, nucleoli and nucleation; The area where genetic material (a circular DNA molecule) is concentrated is called pseudonucleus; Without chromosomes, DNA will not combine with protein; The organelles only have ribosomes; It has a cell wall whose composition is different from that of eukaryotic cells.

2. Eukaryotic cells: cells are large, with nuclear membranes, nucleoli and eukaryotes; There are a certain number of chromosomes (DNA binding protein); There are many kinds of organelles.

Prokaryote: an organism composed of prokaryotic cells. Such as: cyanobacteria, bacteria (such as nitrifying bacteria, lactic acid bacteria, Escherichia coli, pneumococcus), actinomycetes, mycoplasma and so on. All belong to prokaryotes.

4. Eukaryote: an organism composed of eukaryotic cells. Such as animals (paramecium, amoeba), plants, fungi (yeast, mold, myxomycetes) and so on.

Third, the establishment of cell theory:

1, 1665 robert hooke, an Englishman, observed the cork slices with a microscope designed and manufactured by himself (the magnification is 40- 140 times), described the structure of plant cells for the first time, and named cells with Latin cella for the first time.

2. 1680 A. van Leeuwenhoek of the Netherlands observed living cells for the first time, and observed protozoa, human sperm, red blood cells of salmon, bacteria in dental calculus, etc.

3.65438 to 1930s, Germans Schleiden and Wang Shi proposed that all animals and plants are composed of cells, and cells are the basic units of all animals and plants. This theory, called "cell theory", reveals the unity of organism structure.

Chapter II Molecules Constituting Cells

Section 1 Elements and Compounds in Cells

1. 1. The biological world and the abiotic world are unified: the chemical elements that make up cells can be found in the abiotic world.

2. There is a difference between the biological world and the abiotic world: the content of chemical elements in cells that constitute organisms is obviously different from that in the abiotic world.

Second, there are more than 20 chemical elements that make up organisms:

Macroelements: carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, calcium, magnesium, potassium, etc.

Trace elements: iron, manganese, boron, zinc, copper and molybdenum;

Basic element: c;

Main elements; Carbon, oxygen, hydrogen, nitrogen, sulfur and phosphorus;

The cell contains at most 4 elements: c, o, h, n;

water

Inorganic inorganic salt

Constituent cell protein

Compound lipid

Organic sugar

nucleic acid

3. The most abundant compound in living cells is water (85%-90%); The most abundant organic matter is protein (7%-

10%); The chemical element with the largest proportion of cell fresh weight is O, and the chemical element with the largest proportion of dry cell weight is C.

The main undertaker of life activities in the second quarter-protein.

First, related concepts:

Amino acid: the basic unit of protein. There are about 20 kinds of amino acids that make up protein.

Dehydration condensation: The amino group (-—NH2) of one amino acid molecule is connected with the carboxyl group (-—COOH) of another amino acid molecule, and at the same time one molecule of water is lost.

Peptide bond: chemical bond (—NH—CO—) connecting two amino acid molecules in a peptide chain.

Dipeptide: a compound formed by the condensation of two amino acid molecules, which contains only one peptide bond.

Polypeptide: A chain structure formed by the condensation of three or more amino acid molecules.

Peptide chain: Polypeptide is usually a chain structure, called peptide chain.

Second, the general formula of amino acid molecules:

3. Characteristics of amino acid structure: each amino acid molecule contains at least one amino group (-NH2) and one carboxyl group (-COOH), and both amino groups and one carboxyl group are connected to the same carbon atom (for example, those with -NH2 and -COOH but not connected to the same carbon atom are not called amino acids); Different R groups produce different kinds of amino acids.

4. The diversity of protein is due to the different number, types and arrangement order of amino acids that make up protein, and the ever-changing spatial structure of polypeptide chains.

Verb (abbreviation of verb) protein's main function (main undertaker of life activities):

① Important substances that constitute cells and organisms, such as actin;

2 catalysis: such as enzymes;

③ Regulation: such as insulin and growth hormone;

④ Immune function: such as antibody and antigen;

⑤ Transport: such as hemoglobin in red blood cells.

Correlation calculation of intransitive verbs:

① Number of peptide bonds = number of water molecules removed = number of amino acids-number of peptide chains

② The number of carboxyl groups (COOH) or amino groups (NH2) = the number of peptide chains.

Section 3 Carrier of Genetic Information-Nucleic Acid

Types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

2. Nucleic acid: A substance that carries genetic information in cells and plays an important role in the heredity, variation and protein synthesis of organisms.

Third, the basic unit of nucleic acid is: nucleotide, which consists of one molecule of phosphoric acid, one molecule of five-carbon sugar (DNA is deoxyribose, RNA is ribose) and one molecule of nitrogenous bases; The nucleotides that make up DNA are called deoxynucleotides, and the nucleotides that make up RNA are called ribonucleotides.

The bases contained in DNA are adenine (a), guanine (g), cytosine (c) and thymine (t).

The bases contained in RNA are adenine (a), guanine (g), cytosine (c) and uridine (u).

Verb (abbreviation of verb) distribution of nucleic acid: the DNA of eukaryotic cells is mainly distributed in the nucleus; Mitochondria and chloroplasts also contain small amounts of DNA；; RNA is mainly distributed in cytoplasm.

Sugar and lipid in cells in the fourth quarter

First, related concepts:

Sugar: it is the main energy substance; Mainly divided into monosaccharides, disaccharides and polysaccharides.

Monosaccharide: sugar that cannot be hydrolyzed again. Such as glucose.

Disaccharide: A sugar that can produce two monosaccharides after hydrolysis.

Polysaccharide: a sugar that can produce many monosaccharides after hydrolysis. The basic unit of polysaccharide is glucose.

Soluble reducing sugar: glucose, fructose, maltose, etc

Second, the comparison of sugar:

Main functions of common species distribution of classification elements

Monosaccharide c

H

O ribonucleic acid of animal and plant components

Deoxyribose

Glucose, fructose and galactose are important energy substances.

Disaccharide sucrose plant∕

maltose

Lactose animal

Polysaccharide starch plants plant energy storage substance

Main components of cellulose cell wall

Glycogen (glycogen, muscle glycogen) animal energy storage substance

Third, the comparison of lipids:

Classification element common category function

Lipid fat c, h, O ∕ 1, the main energy storage substances.

2, heat preservation

3, reduce friction, buffer decompression

Phospholipids c, h, o

Main components of (n, P) ∕ cell membrane

Sterol cholesterol is related to cell membrane fluidity.

Sex hormones maintain biological secondary sexual characteristics and promote the development of reproductive organs

Vitamin D is beneficial to the absorption of calcium and phosphorus.

Section 5 Inorganic substances in cells

First, the main points of knowledge about water

There is a functional relationship between formal content and existence.

Water free water is about 95% 1, a good solvent.

2. Participate in various chemical reactions

3. Transport nutrients and metabolic wastes, which can be transformed into each other; When metabolism is vigorous, the free water content increases, on the contrary, the content decreases.

About 4.5% of the cell structure is combined with water, which is an important component.

Second, inorganic salts (mostly in ionic form) function:

(1) constitute some important compounds, such as chlorophyll and hemoglobin.

(2), to maintain the life activities of organisms (such as animals will twitch because of calcium deficiency)

③ Maintain acid-base balance and adjust osmotic pressure.

Chapter III Basic Structure of Cells

Section 1 Cell membrane-the boundary of the system

1. Cell membrane composition: mainly lipids (about 50%) and protein (about 40%), and a small amount of sugar.

(about 2%- 10%)

Second, the function of cell membrane:

(1) separate cells from the external environment.

(2), control substances in and out of the cell.

③ Information exchange between cells.

3. Plant cells contain cell walls, the main components of which are cellulose and pectin, which can support and protect cells; Its nature is completely permeable.

Division of labor and cooperation in organelles-system

First, related concepts:

Cytoplasm: Protoplasm inside and outside the cell membrane, called cytoplasm. Cytoplasm mainly includes cytoplasmic matrix and organelles.

Cytoplasmic matrix: The liquid part of cytoplasm is the matrix. It is the main place for cell metabolism.

Cytoplasmic organelle: A general term for various subcellular structures with specific functions in cytoplasm.

Second, the comparison of eight organelles:

1, Mitochondria: (granular, rod-shaped, with a double membrane, which is common in animal and plant cells, with a small amount of DNA and RNA protruding from the intima to form ridges, and there are many enzymes related to aerobic respiration in the intima, matrix and granules), Mitochondria is the main place for cells to carry out aerobic respiration, and about 95% of the energy needed for life activities comes from Mitochondria, which is the "power workshop" of cells.

2. Chloroplast: (oblate ellipsoid or spherical, with double-layer membrane, mainly existing in mesophyll cells of green plants), chloroplast is the organelle for photosynthesis of plants, and it is the "food workshop" and "energy conversion station" of plant cells, (containing chlorophyll and carotenoids, as well as a small amount of DNA and RNA, and chlorophyll is distributed on the membrane of basement membrane. There are enzymes needed for photosynthesis on the membrane of layered structure and in the matrix of chloroplast.

3. Ribosome: ellipsoidal granules, some attached to endoplasmic reticulum, some free in cytoplasmic matrix. It is the place where amino acids in cells synthesize protein.

4. Endoplasmic reticulum: a network connected by membrane structure. It is the "workshop" for the synthesis and processing of intracellular protein and lipid synthesis.

5. Golgi apparatus is related to the formation of cell wall in plant cells and the processing, classification and transportation of protein (secreted protein) in animal cells.

6. Centrosome: Each centrosome contains two centrioles, which are arranged vertically and exist in animal cells and lower plant cells, and are related to cell mitosis.

7. Vacuole: It mainly exists in mature plant cells, and there is cell fluid in the vacuole. Chemical composition: organic acids, alkaloids, sugars, protein, inorganic salts, pigments, etc. It has the functions of maintaining cell morphology, storing nutrients and regulating cell osmotic water absorption.

8. Lysosome: Known as the "digestive workshop", it contains a variety of hydrolases, which can decompose aging and damaged organelles, engulf and kill viruses or germs that invade cells.

Thirdly, the synthesis and transport of secreted proteins:

Ribosome (synthetic peptide chain) → endoplasmic reticulum (processed into protein with a certain spatial structure) →

Golgi apparatus (further modified and processed) → vesicle → cell membrane → extracellular.

Four. Biofilm system consists of organelle membrane, cell membrane and nuclear membrane.

Section III Core-Control Center of the System

1. The function of the nucleus: it is the genetic information base (the place where genetic materials are stored and copied) and the control center of cell metabolism and heredity;

Second, the structure of the nucleus:

1. Chromatin: composed of DNA and protein. Chromatin and chromosome are two existing states of the same substance in different periods of cells.

2. Nuclear membrane: double membrane, which separates nuclear matter from cytoplasm.

3, nucleoli: related to the synthesis of some RNA and the formation of ribosomes.

4. Nuclear pore: realize material exchange and information exchange between nucleus and cytoplasm.