1. Nucleoside: A compound formed by condensation of pentose and base through glycosidic bond.
2. Nucleotide: A compound in which the hydroxyl group of pentose in nucleoside molecule is linked to phosphate molecule through phosphate bond.
3. Nucleic acid: A polymer composed of many single nucleotides linked by phosphodiester bonds.
4. Nucleic acid denaturation: Under the action of some physical and chemical factors, the hydrogen bond in nucleic acid molecules is destroyed, the double helix structure is loosely separated, the physical and chemical properties are changed, and the original biological activity is lost.
5. Renaturation or annealing of DNA: Under appropriate conditions, two complementary strands of denatured DNA can be paired again to restore the natural double helix conformation, which is called renaturation. Thermodenatured DNA can be renaturated after slow cooling, a process called annealing.
6. Primary structure of DNA: The type, quantity, arrangement order and connection mode of a single nucleotide in the deoxypolynucleotide chain that constitutes DNA are called the primary structure of DNA. It can also be considered as the arrangement order of bases in deoxypolynucleotide chains.
7. Melting temperature, melting temperature or TM: From the beginning of melting to complete melting, the denaturation of DNA is completed in a fairly narrow temperature range. In this range, the temperature at which ultraviolet absorption reaches 50% of the maximum value is called the melting temperature of DNA. Because this phenomenon is similar to the melting process of crystals, it is also called melting temperature.
8. nucleic acid hybridization: DNA single strands from different sources can have complementary base sequences with DNA or RNA strands, and local double strands can be formed through denaturation and renaturation, which is the so-called hybrid double strand. This process is called nucleic acid hybridization.
9. Base pairs: Adenine and thymine, guanine and cytosine in nucleic acid molecules are always connected by hydrogen bonds, forming a fixed base pairing relationship, so base pairs are also called base complementation.
10. Coloring effect means that compared with natural DNA, the double helix of denatured DNA is destroyed and the base is fully exposed, so the ultraviolet absorption is increased. This phenomenon is called coloring effect.
Hypochromic effect means that if denatured DNA renaturates to form a double helix structure, its ultraviolet absorption will decrease. This phenomenon is called hypochromic effect.
1 1. Molecular hybridization: Two single-stranded DNA molecules with complementary bases, or DNA single-stranded molecules and RNA molecules, can be annealed and renaturated to form double-stranded DNA molecules or DNA/RNA heterogeneous double-stranded molecules after denaturing conditions are removed. This process is called molecular hybridization.
12, palindrome structure: Two sequences with the same structure and opposite directions contained in double-stranded DNA are called reverse repeats, also known as palindrome structure.
Second, protein.
1. Isoelectric point (pI) of amino acids: In a solution with a certain pH, amino acids dissociate into cations and anions with the same trend and degree, and become facultative ions, which are electrically neutral. At this time, the pH value of the solution is called the isoelectric point (pI) of amino acids.
2. Primary structure of protein: In protein molecule, the amino acid residue sequence from N-terminal to C-terminal is called the primary structure of protein.
3. The secondary structure of protein refers to the local spatial structure of a peptide chain in protein molecule, that is, the relative spatial position of skeleton atoms in the main chain of the peptide chain, and does not involve the conformation of the side chain of amino acid residues.
4. Molecular diseases: diseases caused by defects of genes or DNA molecules, which lead to abnormal synthesis of RNA and protein in cells and corresponding changes in human structure and function.
5. The tertiary structure of protein refers to the relative spatial position of all amino acid residues in the whole peptide chain, that is, the arrangement position of all atoms in the whole peptide chain in three-dimensional space.
6. Domain: The tertiary structure of proteins with large molecular weight can often be divided into 1 and several spherical or fibrous regions.
Folded tightly, each line has its own function, called domain.
7. Four-level structure of protein: The spatial arrangement of subunits in protein molecule and the layout and interaction of contacting parts of subunits are called the four-level structure of protein.
8. Isoelectric point of protein: In a solution with a certain pH, protein dissociates into cations and anions with the same trend and degree, and becomes facultative ions, which are electrically neutral. At this time, the pH value of the solution is called the isoelectric point (pI) of protein.
9. Degeneration of protein: Under the action of some physical and chemical factors, its specific spatial conformation is destroyed, that is, the ordered spatial structure becomes disordered, resulting in the change of its physical and chemical properties and the loss of biological activity, which is called protein degeneration.
10. Dissolution of salt: When a small amount of salt is added, it is easy to dissociate into charged ions, which is beneficial to stabilize the charge carried by protein, thus increasing the solubility of protein.
1 1. salting-out: adding salt (neutral) to protein solution neutralizes the surface charge of protein and destroys the hydration film, resulting in the removal of the stability factor of protein in aqueous solution and precipitation.
12. Dialysis: The method of separating macromolecular protein from small molecular compounds by using the principle of semi-permeable membrane is called dialysis.
13. Ultrafiltration method: positive pressure or centrifugal force is applied to make protein solution pass through an ultrafiltration membrane with a certain molecular weight cut off, so as to concentrate protein solution, which is called ultrafiltration method.
14. Electrophoresis: protein is a charged particle whose pI is higher or lower in solution. Because of the different charged properties, quantity, molecular weight and shape of different protein, the technology of separating various protein under the action of electric field is called electrophoresis.
15. isoelectric focusing electrophoresis: polyacrylamide gel with continuous and stable linear pH gradient is used for electrophoresis, so that it can be separated according to different pI of protein in electric field. This kind of electrophoresis is called isoelectric focusing electrophoresis.
16. Super-secondary structure: a transitional structure level between the secondary structure and the tertiary structure of protein, which is formed by the interaction of some conformational units of the secondary structure in the process of peptide chain folding.
Third, enzymes.
1. Isozyme: refers to a group of enzymes that catalyze the same chemical reaction, but have different molecular structure, physical and chemical properties and even immunological properties.
2. Enzymes: Macromolecules produced by living cells are mostly protein, and some are nucleic acids or deoxynucleic acids.
3. Monomer enzyme: an enzyme with only a tertiary structure, that is, an enzyme with only one peptide chain, is called monomer enzyme.
4. Oligosaccharide: An enzyme composed of several (at least two) identical or different subunits connected by non-valence bonds is called oligosaccharide.
5. Multifunctional enzyme (tandem enzyme): An enzyme formed by polypeptide chains with multiple catalytic functions is called multifunctional enzyme.
6. Binding enzyme: an enzyme composed of protein and non-protein parts.
7. Simple enzyme: an enzyme consisting only of amino acids, with no non-protein part.
8. Active center of the enzyme: Some chemical groups closely related to the activity of the enzyme may be far apart in primary structure, but they are close to each other in spatial structure, forming a region with a specific spatial structure, which can specifically combine with the substrate and transform the substrate into products. This region is called the active center or site of the enzyme.
9. Induced Fit Hypothesis: Before the enzyme is closely combined with the substrate, it must be closely combined with the substrate, induced, deformed and adapted to each other, and then combined with each other. This process is called the induced fitness hypothesis of enzyme-substrate binding.
10. Enzymatic reaction kinetics: Enzymatic reaction kinetics is to study the effects of physical and chemical factors such as enzyme concentration, substrate concentration, pH, temperature, inhibitors and activators on enzymatic reaction speed and their changing rules.
1 1. Irreversible inhibition: It means that the inhibitor usually binds to the necessary groups on the active center of the enzyme with valence of * *.
Irreversible inhibition is the inhibition that the enzyme loses its activity due to combination, and cannot be removed by dialysis, ultrafiltration and other methods.
12. Reversible inhibition: refers to the reversible combination of inhibitors with enzymes and/or enzyme-substrate complexes through non-* * valence bonds, which reduces or disappears the activity of enzymes. Inhibitors can be removed by dialysis, ultrafiltration and other methods. This inhibition is called reversible inhibition.
13. Competitive inhibition: Some inhibitors are similar to the substrate of an enzyme and can compete with the substrate for the active center of the enzyme, thus preventing the enzyme from combining with the substrate to form an intermediate product. This kind of inhibition is called competitive inhibition.
14. Non-competitive inhibition: Some inhibitors combine with essential groups outside the active center of the enzyme, which does not affect the combination of the enzyme and the substrate, and the combination of the enzyme and the substrate does not affect the combination with the inhibitor, but the enzyme-substrate-inhibitor complex cannot further release products. This kind of inhibition is called noncompetitive inhibition.
15. Anti-competitive inhibition: Inhibitors can only combine with enzyme-substrate complexes, reducing the amount of intermediate products, thus playing an inhibitory role. This inhibition is called anticompetitive inhibition.
16. Activity unit of enzyme: it is a measure of enzyme activity, reflecting the amount of enzyme required for enzyme reaction to produce a certain amount of products or consume a certain amount of substrates per unit time under specified conditions.
17. International unit of enzyme: under certain conditions, it catalyzes 1 per minute. The amount of enzyme required to convert a molded substrate into a product is one international unit (IU).
Proenzyme 18: Some enzymes are inactive when synthesized or secreted in cells. The precursor of these inactive enzymes is called zymogen.
19. Activation of zymogen: The process of transforming zymogen into active enzyme is called activation of zymogen, and the activation of zymogen is actually the process of forming or exposing the active center of enzyme.
20. Allosteric enzyme: An enzyme whose catalytic activity is changed by reversible binding of allosteric effectors with sites outside the active center of the enzyme molecule.
2 1. enzyme specificity: an enzyme only acts on one or a class of compounds or some chemical bonds, catalyzing some chemical reactions and generating some products. This selectivity of enzyme is called specificity or enzyme specificity.
22. Prochiral molecule: If a symmetric molecule loses its symmetry after being replaced by a group and becomes an asymmetric molecule, then the original symmetric molecule is called a "prochiral molecule".
The changed carbon atom is called "prochiral carbon atom".
23. Specific activity of enzyme: number of enzyme activity units per mg of enzyme protein.
24. Allosteric effect (allosteric effect): A phenomenon that a substance that is not directly related to the activity of protein binds to other sites (allosteric sites) other than the active site of protein, causing the conformational change of protein molecules, thus leading to the change of the activity of protein. 25. Coenzyme: As a cofactor of an enzyme, organic molecules do not catalyze themselves, but generally have the function of transferring electrons, atoms or certain functional groups (such as groups participating in redox or carrying acyl groups) in enzymatic reactions. In most cases, coenzyme can be removed by dialysis.
26. Accessory: A small molecule organic substance that is closely bound to valence * * in the coenzyme of an enzyme, which is very closely bound to the enzyme or protein and cannot be removed by dialysis.
27.km value: km is equal to the substrate concentration when the enzyme reaction speed reaches half of the maximum reaction speed, which is one of the characteristic constants of the enzyme.