浙江万里学院基因工程试题(五)参考答案.doc

浙江万里学院《基因工程》试题（五）参考答案

I. Definition:
1. Genes and Genome: Gene expression refers to a protein or functional RNA, the basic unit; genome: is a complete set of genes contained in biological.
2. Cos-Plasmid: Cosby l-DNA plasmid that contains cos areas at both ends of plasmid As the λ-DNA packaging proteins recognize only the sticky at the end of a short sequence of cos zone. Will this DNA together with the plasmid, the recombinant plasmid.
3. Bactericidal peptides: the ability to play the role of bactericidal peptides, and many insects have such peptides, can destroy the bacteria cell membrane, causing ion channels, leading to leakage of cellular inclusions.
4. Satellite DNA: tonsure in CsCl isopycnic ultra-centrifugation, the emergence of a peak, and 1 or 2 small peaks, this small peak to the peak in terms of peak especially like the satellite, so called satellite DNA.
5. Single-strand binding protein: one which can be with single-stranded DNA binding proteins to tetrameric form and single-stranded DNA binding, since maintaining the existence of single-chain role.
6. Degenerate codes: from more than one code encoding the same amino acid is called a degenerate (degeneracy), corresponding to the same amino acid code is called synonymous code or code degeneracy.
7. Reverse mutation: mutation phenotype there are two types, one type is forward mutation from the wild type to mutant, and the other is a mutant to the wild-type known as the reverse mutation.
8. Telomerase: a RNA-protein complex, which can be its RNA as a template by reverse transcription process to extend the right end of the DNA chain
9. Code of the swing: In the code and anti-code pair, the first two pairs of strict observance of the principle of base pairing, the third base pairs have a certain degree of freedom.
10. Temporal gene: only a certain period in development can be expressed by a number of specific genes.

II. Fill-in:
1. (AP) 2. (Thymus) (pyrimidine dimer) 3. (RNA) 4. (CGU)
5. (Site-specific), (4,6,8 months bp), (palindromic sequences of DNA) 6. (Repression mechanism) (weakening of the mechanism) 7. (Metabolites on the regulation of gene activity), (weakening of the child on the impact of gene activity), (degradation products of the regulation of gene activity), (bacteria emergency response) 8. (Strict type), (loose type) 9. (Zinc finger motif); (helix turn helix motif); (helix-loop-helix motif); (leucine zipper motif)
III. Multiple-choice:
1. (B) 2. (B) 3. (C) 4. (B) 5. (D) 6. (D) 7. (A) 8. (B) 9. (B) 10. (C)

IV True or False:
1. (×) 2. (√) 3. (×) 4. (×) 5. (×) 6. (√) 7. (×) 8. (√) 9. (√) 10. (×)

V. Short Answer :
1. Design an experiment to prove that DNA replication is semi-conservative conducted in a way?
① 15N and 14N respectively, marked DNA.
② Because 15N DNA density than 14N DNA of density, density gradient centrifugation in cesium chloride, the two different densities of the DNA located in a different zone.
③ 15N heavy-density zone, 14N light-density zone, 15N and 14N-DNA medium density zone.
④ degeneration before the hybrid molecule with a medium density, modified after the zone is divided into two, namely, heavy density band (15N DNA) and low-density zone (14N DNA). Only test the theory of semi-conservative replication to get a satisfactory explanation.

2. Description of protein trans-membrane transport mechanism?
① In the process of protein synthesis in the N-terminal 15 to 36 amino acid residues of the peptide --- signal peptide, that he could guide the protein peptide chain to reach through the endoplasmic reticulum.
② then in the endoplasmic reticulum signal peptidase removed, protein N terminal signal peptide does not.
③ In the cytosol there is a signal recognition particle (SRP), containing 300 nucleotides of the 7S small molecule RNA (small cytoplasm scRNA) and six kinds of protein ribonucleoprotein, appears in the signal peptide, can identify and combine signal peptide and the ribosome, so that translation pause, and with the membrane of the SRP receptor protein (docking protein) binding, transmembrane peptide chain.

3. Respectively, say 5 or more RNA function?   
tRNA amino acid transporter   rRNA ribosomal component into a sub-mRNA protein synthesis in a sub-template hnRNA mature mRNA precursor of a sub- snRNA involved in splicing a sub-hnRNA

4. Examples of tissue-specific cDNA differential screening method?
① Preparation of two kinds of cell populations, gene expression, in which a cell or high expression in the other cells did not express or low expression.
② then compared to find the target gene by hybridization.
③ For example: in tumor occurrence and development process, the tumor cells and normal cells showed different levels of the mRNA, therefore, can be screened by differential hybridization with the tumor-related genes. Induction method can also be used to screen out the genes induced.