Divided by element content: large amounts of elements: C, H, O, N, P, S, K, Ca, Mg, etc. Trace elements: Fe, Mn, Zn, Cu, B, Mo (molybdenum), I (iodine), etc.

Divided according to the effect of elements on organisms. Main elements: O>C>H>N>P>S (content, that is, the percentage of fresh weight of cells) Basic elements: C (the most basic element that constitutes cells), H, O, N

Water 70%~90%, protein 7%~10%, nucleic acid and sugar 1%~1.5%, lipid 1%~2%, inorganic salt 1%~1.5% Organic matter contains vitamins

Cell fresh weight: The most abundant compound is water and the element is oxygen The most abundant organic matter is protein The most abundant chemical element is hydrogen

Dry cell weight: The most abundant compound is protein The most abundant element is carbon

Reducing sugar Fehling's reagent → brick red precipitate (water bath heated to 50℃~60℃)

starch iodine → blue

Fat Sudan III stain → orange (microscopic examination)

Protein (peptide bond) biuret reagent → purple

Water exists in two forms in cells. Most of the water is free and can move freely, which is called free water; part of the water is combined with other substances in the cell, which is called bound water.

free water

bound water

Function: ① Plays an important role in maintaining the stability of body temperature ②Transportation ③Maintain the inherent posture of the plant ④ Plays an important role in regulating the life activities of organisms ⑤Lubrication effect Participate as a reactant in many biochemical reactions in metabolism (such as photosynthesis, cellular respiration, hydrolysis of polysaccharides, proteins, and nucleic acids)

Most inorganic salts in cells exist in the form of ions. A few combine with other compounds

Physiological effects: 1. The components of certain complex compounds 2. Maintain the life activities of cells and organisms 3. Maintain cell osmotic pressure balance and acid-base balance

Sugar is the main energy substance

Monosaccharides: Glucose, known as the "fuel of life", is the main energy substance required for cell biological activities (unhydrolyzable sugars)

Disaccharide: formed by the dehydration and condensation of two molecules of monosaccharide

Polysaccharide: Starch, energy storage substance in plant cells

Starch → (enzyme, hydrolysis) maltose → (enzyme, hydrolysis) → glucose → (enzyme, oxidative decomposition) → energy release

Fat is a good energy storage material in cells

Storage lipids: fat (C, H, O)

Structural lipids: phospholipids (C, H, O, N, P)

Active lipids: sterols (C, H, O)

Grease is mainly composed of glycerol and fatty acids. Grease molecules are insoluble in water.

Compared with sugar oxidation, fat has higher C and H content than sugar, consumes more oxygen (more water is generated under the same mass), and has a slower reaction rate, so it can release more energy.

Oxidation of sugars can occur under both aerobic and anaerobic conditions

Structural proteins: important substances that constitute the structure of cells and organisms

Catalysis: most enzymes (a few are RNA) (Supplement: most enzymes are proteins in nature)

Transport role: carrier protein, hemoglobin

Regulatory effect (information transmission): Regulates the body’s life activities, such as insulin (regulates blood sugar concentration, if there is a lack of insulin, diabetes will occur)

Immunity: Antibodies

The diversity of protein structures determines the diversity of protein functions

General structural formula: C2H4O2N R

Structural features: 1. Each amino acid contains at least one amino group and one carboxyl group 2. Both have an amino group and a carboxyl group connected to the same carbon atom.

1. The carboxyl group is acidic 2.Alanine is the simplest amino acid 3. Essential amino acids: "A brings a brightly colored book"

1. Amino acids dehydrate and condense to form a peptide bond and remove a molecule of water. 2. The amino and carboxyl groups on the R group generally do not participate in the dehydration condensation reaction. 3. Biological macromolecules: proteins, polysaccharides, nucleic acids 4. Elements such as C, H, O, N → amino acids (dehydration condensation) → dipeptides → polypeptides (one or several peptide bonds, twisting and folding) → proteins

Root cause: genetic diversity Direct reasons: 1. Different types, numbers and order of amino acids 2. The twisting and folding methods of peptide chains and the spatial structures they form are different.

If the amino acid sequence is changed or the spatial structure of the protein is changed, its physiological functions will be affected or even completely lost.

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

The characteristic of cyclic peptides is that the number of peptide bonds is the same as the number of amino acids. Number of water molecules removed = number of peptide bonds = number of amino acids A cyclic peptide has one more peptide bond than a peptide chain

N peptide chains have at least n free amino groups and at least n free carboxyl groups, which are located at both ends of the peptide chain, and the rest are in the R group.

Relative molecular mass of protein = number of amino acids x average relative molecular mass of amino acids - number of dehydrated molecules x 18 - number of disulfide bonds x 2

N=Number of peptide chains Number of peptide bonds R(N)=Number of amino acids R(N) O=Number of peptide chains x2 Number of peptide bonds R(O)=Number of amino acids×2 R(O)-Number of dehydration C=Number of amino acids x2 R(C) H=Number of amino acids x4-Number of dehydration x2

Denaturation (irreversible): The protein structure is susceptible to the influence of high temperature, over acidity, over alkali, heavy metals, etc., resulting in changes in spatial structure and loss of function, but does not involve the breakage of peptide bonds (can be detected with uret reagent) Undenatured (reversible): the solubility of the protein in the salt solution is reduced, but the spatial structure remains unchanged, that is, salting out

Eukaryotic cells: DNA is mainly distributed in the nucleus, with small amounts of DNA also contained in mitochondria and chloroplasts. RNA is mainly distributed in the cytoplasm, with a small amount also distributed in the nucleus.

Prokaryotic cells: DNA is mainly found in the nucleoid, and plasmids (small circular DNA molecules) are present in the cytoplasm. RNA is mainly distributed in the cytoplasm

DNA deoxyribonucleic acid, RNA ribonucleic acid

A molecule of nucleotide is composed of a molecule of nitrogenous base, a molecule of five-carbon sugar and a molecule of phosphoric acid

DNA is composed of two deoxynucleotide strands, forming a double helix structure. The two strands are connected by hydrogen bonds (such as A=T) RNA is composed of a chain of ribonucleotides, which is unstable and prone to genetic mutations.

There are: phosphoric acid, 2 kinds of five-carbon sugars, 5 kinds of bases, making up 8 kinds of nucleotides in the organism Adenine (A), guanine (G), cytosine (C), thymine (T), uracil (U) 4 types of deoxynucleotides, 4 types of ribonucleotides

1. The genetic information of organisms is stored in DNA molecules. The deoxynucleotide sequences of each individual's DNA have their own characteristics. If the number is not limited, when connected into long chains, the order of arrangement is extremely diverse, and the information capacity is very large. 2. Specificity: For a certain organism, the sequence of nucleotides in its genetic material is specific.

Carbon is the core element of life