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1、Biochemistry is the application of chemistry to the study of biological processes at the cellular and molecular level. Generally speaking it is concerned with the chemistry of those compositions (such as protein, fat, saccharide and nucleic acid )found in living organisms and their metabolic process
2、.Saccharide 糖is a general synonym for sugars. They can be classified as monosaccharide, oligosaccharide少 and polysaccharide. Monosaccharide are the simplest carbohydrates. They cannot be hydrolyzed into simpler sugars. Examples are ribose, glucose, fructose and galactose. Monosaccharides are classif
3、ied by the number of carbon atoms they contain: Triose, Tetrose, Pentose, Hexose, Heptose, Octose, Nonose, Decose,GlucoseFructoseGalactoseRiboseAn oligosaccharide is a saccharide polymer containing a small number (typically three to ten) of component sugars, such as lactose and sucrose.蔗糖 Polysaccha
4、rides are relatively complex carbohydrates. They are polymers made up of many monosaccharides, such as starch淀粉, glycogen 糖原and. As a group, the polysaccharides play diverse and important roles within the biology of life processes; however, they can be divided into two broad groups according to thei
5、r function.Structural polysaccharides (such as cellulose)These polysaccharides are water insoluble and usually perform as strong support material in plants and animals.Storage polysaccharides (such as glycogen)LactosesucroseStarchIn humans and other vertebrates脊椎动物 it is principally stored in the li
6、ver and muscles and is the main form of stored carbohydrate in the body, acting as a reservoir of glucose (which the glycogen can be broken down into) for when the body is being starved of food.According to their component, polysaccharide can be divided intoHomopolysaccharide: polysaccharide formed
7、from only one kind of monosaccharide. Heteropolysaccharide: polysaccharide formed from different kinds of monosaccharideProteins are macromolecules大分子 made of amino acids氨基酸 and joined together by peptide 肽 bonds between the carboxyl 羧基and amino groups of adjacent amino acid residues. Each amino aci
8、d contains: (1) Carboxyl group (-COO-) (2) Amino group (-NH2) (3) Side chain (R) unique to each amino acid Most proteins fold into 3-dimensinal structures. Primary structure,secondary structure, tertiary structure and quaternary structure.Functions performed by proteins1.Biocatalysis生物催化剂Many protei
9、ns are enzymes that catalyze 向下， 反biochemical reactions and are vital有生命的 to metabolism.Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called substrates底物, and the enzyme converts them into different molecules, the products.Cofactors辅因子 and
10、 coenzymesSome enzymes do not need any additional components to show full activity, these enzymes are called simple enzyme。While others require non-protein molecules called cofactors. Cofactors can be either inorganic无机 (such as metal ions离子) or organic compounds (such as vitamin).Those loosely boun
11、ded cofactors which can be eliminated by dialysis透析 are coenzymes, while those tightly bounded cofactors which can not be eliminated by dialysis are prosthetic group辅基. Holoenzyme全 is composed of apoenzyme分离 （酶蛋白）and cofactor.Zymogen or proenzyme 酶原is an active enzyme precursor. such as pepsinogen胃蛋
12、白酶原 and most blood clotting factors involved in coagulation. Inhibitors are molecules that decrease enzyme activity; activators are molecules that increase enzyme activity. Many drugs are enzyme inhibitors. ACEI angiotensin converting enzyme inhibitor -lactamase inhibitor, clavulanic acid (克拉维酸)peni
13、cillin2.metabolic regulation代谢调节： many hormones are proteins such as insulin which can regulate blood sugar levels. 3.immunol protection免疫保护： antibodies are immunoglobulin 4.Transportation运输: Hemoglobin血红蛋白 can transport oxygen and carbon dioxide 5.Structural or mechanical functions： Actin肌纤蛋白 and m
14、yosin肌球蛋白 in muscleNucleic acidNucleic acid is composed of nucleotide核苷酸. Each nucleotide consists of three components: a nitrogenous heterocyclic 异，杂base,碱基 which is either a purine 嘌呤 or a pyrimidine嘧啶; a pentose戊糖; and a phosphate group磷酸基.RNA is ribonucleic acid composed of adenine腺嘌呤, guanine鸟嘌
15、呤, cytosine,胞嘧啶 uracil尿嘧啶 and D-ribose. DNA is deoxyribonucleic acid脱氧核糖核酸 composed of adenine, guanine, cytosine ,thymine胸腺嘧啶 and deoxyribose. Both ribose and deoxyribose are pentose. nucleotide monomers form polynucleotide多 核苷酸s by phosphodiester bond磷酸二脂键 Two polynucleotides associate to form a d
16、ouble helix螺 旋 Genetic information is carried by the sequence of base pairsWhat is a gene?Genes are sequences of DNA which serve as blueprints for the production of proteins in all living things. DNA is found in all cells, usually in the nuclei. In bacteria and viruses, which do not have nuclei, the DNA floats within the cell. DNA is composed of six molecules: sugars, phosphates磷酸盐 and four base
