生物化学作业.docx

1、生物化学作业Section Aand B1. The typical structure of a prokaryotic cell and a eukaryote cell? 1. Typical stuructures：（draw a picture to describe typical sturcutures of both cells is also suggested）Prokaryote cell: Mesosome, NucleoidEukaryotic cell：Nucleus，Plasma membrane，Endoplasmic reticulum，Golgi appar

2、atus，Mitochondria，Chloroplasts，Lysosomes，Peroxisomes，Cytosol2. The main function of a proteinCatalysis:-LDH (lactate dehydrogenase, in the glycolytic pathway)-DNA polymerase (in DNA replication)Transport:-hemoglobin (transports O2 in the blood)-lactose permease (transports lactose across the cell me

3、mbrane)Structure:-collagen (connective tissue)-keratin (hair, nails, feathers, horns)Motion:-myosin (muscle tissue)-actin (muscle tissue, cell motility)3. Right down the 20 standard amino acids, and summarize the main properties of most -amino acids. Draw the structures of 20 standard amino acids, T

4、he -carbon has always four substituents and is tetrahedral. All (except proline) have an acidic carboxyl group, a basic amino group, and an hydrogen connected to the carbon, each amino acid has an unique fourth substituent R with the exception of glycine (the fourth substituent is also hydrogen)4. A

5、ccording to the structure of R residue, how to classify acid and basic AAS?Amino acids are dipolar ions in aqueous solution and are amphoteric, the property of AAS is varied in the buffer based on the titration experiment. According to the different structure of R residue in AAS, they are classified

6、 into:“Acidic” amino acids : containing additional carboxyl groups which are usually ionized. Those amino acids with an ionizable side-chain (Asp, Glu, Arg, Lys, His, Cys, Tyr) have an additional acidbase group.“Basic” amino acids: containing positively charged groups such as Arg and Lys.5. What is

7、the typical structure in the secondary structure of a protein?Secondary sturcture in a protein refers to the regular folding of regions of the polypeptide chain. The two most common types are the a-helix,𝛽-sheet.6. What is the noncovalent interaction between side chains that hold the tertiar

8、y structure together?Noncovalent interaction between side chains that hold the tertiary structure together: van der Waals forces, hydrogen bonds, electrostatic salt bridges, hydrophobic interactions.7. Definitions:1. Flow cytometry: Individual cells can be identified using a flow cytometer. Antibodi

9、es, coupled to fluorescent compounds, that bind to molecules on the surface of particular types of cells can be used to separate cells from each other in a fluorescence-activated cell sorter (FACS).2. Enantiomers: Four different groups arranged tetrahedrally around the C atom and thus can exist in e

10、ither the D or L configuration. These two enantiomers are nonsuperimposable mirror images that can be distinguished on the basis of their different rotation of plane-polarized light.3. Peptide bond: The peptide bond is a covalent bond between the -amino group of one amino acid and the -carboxyl grou

11、p of another.4. Primary structure: The linear sequence of amino acids joined together by peptide bonds is termed the primary structure of the protein. The position of covalent disulfide bonds between cysteine residues is also included in the primary structure.5. Secondary structure: Secondary struct

12、ure in a protein refers to the regular folding of regions of the polypeptide chain.6. Tertiary structure: Tertiary structure in a protein refers to the three-dimensional arrangement of all the amino acids in the polypeptide chain. This biologically active, native conformation is maintained by multip

13、le noncovalent bonds.7. Quaternary structure: If a protein is made up of more than one polypeptide chain it is said to have quaternary structure. This refers to the spatial arrangement of the polypeptide subunits and the nature of the interactions between them.8. Prothetic groups: A metal or coenzym

14、e that is covalently attached to the enzyme is called a prosthetic group.9. Motif: are groupings of secondary structural elements that frequently occur in globular proteins. They often have functional significance and can represent the essential parts of binding or catalytic sites that have been con

15、served during the evolution ofprotein families from a common ancestor.10. Domain: Structurally independent units, or families that are connected by sections with limited higher order structure within the evolution same polypeptide.11. Ion exchange chromatography: is a chromatography process that sep

16、arates ions and polar molecules based on their affinity to the ion exchanger，proteins are separated on the basis of their overall (net) charge.12. Affinity chromatography: Affinity chromatography exploits the specific, high affinity, noncovalent binding of a protein to another molecule, the ligand.

17、this technique exploits the specific, often unique, binding properties of the protein, it is often possible to separate the protein from a mixture of hundreds of other proteins in a single chromatographic step.Homework for section C, D1. Write down the following definitions: Active site, prosthetic

18、groups , isoenzyme, free energy change, monoclonal antibody. Active site: The region of the enzyme that binds the substrate, to transforms it into product.Coenzymes: Many enzymes require the presence of small, nonprotein units or cofactors to carry out their particular reaction. A complex organic mo

19、lecule called a coenzyme.Prosthetic groups: cofactors may be inorganic ions or complex organic molecules, some of cofactors that covalently attached to the emzyme is called prothetic groups.Isoenzyme: isoenzymes are different forms of an enzyme which catalyze the same reaction, but which exhibit dif

20、ferent physical or kinetic properties.Free energy change: The difference in energy level between the substrates and product is termed the change in Gibbs fre energy (G).Monoclonal antibody: Antibody produced by a single clone of cells is a monoclonal antibody, which are identical and bind to the sam

21、e antigenic site with identical binding affinities.Complement: The complement system is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promotes inflammation, and attacks the pathogens plasma

22、 membrane. (不需要完全记住，理解即可)2. List the six main classes of enzymes classified by the reaction they catalyze. 3. What is enzyme velocity? Please set the limitation factors that influence the enzyme velocity. Enzyme velocity refers to the rate of an enzyme-catalyzed reaction. The limitation factors incl

23、udes substrate concentration; enzyme concentration; temperature; pH.4. What is the feedback regulation? And please set an example for feedback regulation in its implication in metabolic regulation. A feedback regulation is usually found in metabolic regulation when an enzyme early on in the pathway

24、is inhibited by an end-product of the metabolic pathway in which it is involved.5. What is the basic structure of an allosteric enzyme? Allosteric enzymesareenzymesthat change theirconformational ensembleupon binding of aneffector, which results in an apparent change in binding affinity at a differe

25、nt ligand binding site. (In allosteric enzmes, the binding of a substrate molecule to one active site affects the binding of substrate molecules to other active sites in the enzyme; the different active sites are said to behave cooperatively in binding and acting on substrate molecules.)6. What is t

26、he main function of immune system?The immune system has two main functions; to recognize invading pathogens and then to trigger pathways that will destroy them.7. What is the basic structure and main function of IgG ?Each IgG antibody molecule consists of four polypeptide chains (two identical light

27、 chains and two identical heavy chains joined by disulfide bonds) and has two antigen-binding sites. It provides the majority of antibody-based immunity against invading pathogens and activate complement and trigger macrophages, but is the only antibody that can pass through the placenta and so prov

28、ide immunological protection for the fetus.8. What is the clonal selection theory in humoral immune system? You can simply describe this process by a picture. A large number of antibody-producing cells exist in an animal even before it encounters a foreign antigen, each cell producing only one speci

29、fic antibody and displaying this on its cell surface. An antigen binds to cells that display antibodies with appropriate binding sites and causes proliferation of those cells to form clones of cells secreting the same antibody in high concentration.9. Please set two examples for monoclonal antibody

30、implication in clinical diagnosis and therapy. Any specific example in monoclonal therapy or diagnosis you can find in the following figure:Section E1. Describe the basic structure of cell membrane? What is the main component of membrane lipids?All membranes contain two basic components: lipids and

31、proteins. Some membranes also contain carbohydrate. The composition of lipid, protein and carbohydrate varies from one membrane to another. There are three major types of lipid: the glycerophospholipids the sphingolipids and the sterols.2. What is the typical structure within an intergral protein?Mo

32、st integral proteins have one or more regions of the hydrophobic polypeptide chain that traverse the lipid bilayer. These regions consist mainly of amino acids with hydrophobic side-chains that fold into an -helix and interact noncovalently with the surrounding lipids.3. Describe the process of glucose transport into erythrocytes (an example in passive transport), and glucose transport into interstinal epithelial cells (an example in active transport), and explain the main difference between them.Home work for sectio