浙江万里学院《基因工程》试题（四）参考答案
I. Definition:
1. The standard unit of protein folding: protein secondary structure elements α-helix
and β-sheet through a variety of connecting peptide may form a special geometric
arrangement of the structure of blocks, such a determination of the folding type
commonly referred to as super-secondary structure. Almost all of the tertiary structure
can use these fold types, as well as their combination type to be described will
therefore be referred to as the standard folding units.
2. DNA probe: Yes, with a marked section of a known sequence of DNA, to detect
unknown sequence, screening the target gene and so widely used.
3. Magic Spot: When the bacterial growth process, the experience a general lack of
amino acids, the bacteria will generate an emergency response, and stop all the gene
expression. The emergency response generated signal is guanosine four phosphate
(ppGpp) and guanosine 5 phosphate (pppGpp). PpGpp and the role of pppGpp is not
just one or a few operons, but affects a large number, so that they are the
super-regulator, also known as magic spot.
4. Cis-acting elements: In the DNA of a particular base sequence of the gene
expression play a role in regulation of gene components.
5. Palindromic sequences: DNA fragments with a section of the reverse
complementary sequence, a frequent restriction enzyme sites.
6. Signal peptide: In the process of protein synthesis in the N-terminal 15 to 36 amino
acid residues of the peptides to guide trans-membrane protein.
7. cDNA and cccDNA: cDNA from the mRNA by reverse transcriptase synthesis of
double-stranded DNA; cccDNA is the alienation from chromosomes other than the
double-stranded closed circular plasmid DNA.
8. Blue - White Spot filter: containing LacZ gene (encoding β-galactosidase) enzyme
that breaks down the chromogenic substrate X-gal (5 - bromo -4 - chloro -3 indole-β-D-galactosidase) produces blue, so blue strain. When the foreign DNA
inserted, LacZ gene can not express, strain was white as a means of re-screening of
bacteria. Called the Blue - spot screening.
9. DNase Ⅰ footprinting (DNase Ⅰ footprinting): protein binding in the DNA
fragments that can protect the binding site is not DNAase hydrolysis, electrophoresis
corresponds to the binding site is not bands.
10. Glucose effects: there is the presence of glucose even in the medium by adding
lactose, galactose and other inducers, operon does not start, this phenomenon is
known as effect or as degradation products of glucose inhibition.
II. Fill-in:
1. (Signal peptide), (to assist the correct folding of proteins)
2. (RNA)
3. (Semi-conservative replication), (semi-discontinuous replication).
4. (Functionally related genes in series with the composition of operon structure),
(genome does not exist in intron gene is continuous), (most of the genome coding
region), (a small number of genes overlapping genes)
5. (RNA polymerase Ⅱ)
6.(Formyl-methionyl aminoacyl-tRNA), (formyl methionine), (Met-aminoacyl-tRNA),
(Met-Ala) 7. (CGU) 8. (Guanosine four phosphate ppGpp), (guanosine 5 phosphate
pppGpp), (empty tRNA) 9. (Core promoter element), (common promoter elements)
III. Multiple-choice:
1. (B) 2. (A) 3, (C) 4, (C) 5, (D) 6. (B) 7. (D) 8. (A) 9. (C) 10. (C)
IV True or False:
1. (√) 2. (×) 3. (√) 4. (√) 5. (×) 6. (√) 7. (×) 8. (√) 9. (√) 10. (√)
V. Short Answers:
1. Description eukaryotic DNA replication in the telomere replication process and its
biological significance?
① telomere is a linear eukaryotic chromosomes end of the structural parts of DNA
molecules.
② linear DNA replication is completed, its end due to the hydrolysis of RNA primers
that might arise from shortened. Therefore, telomerase catalyzed the need to carry out
the extension reaction.
③ Telomerase is 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.
④ biological significance: the maintenance of chromosome stability; to ensure the
integrity of DNA replication.
2. Brief bio-genetic material is DNA rather than proteins are the two basic
experiment?
① U.S. Avery infected mice with Streptococcus pneumoniae.
② the United States Hershey with T2 phage infection of E. coli.
③ The main argument experimental evidence that is: absorption of exogenous DNA
of organisms change their genetic potential.
3. DNA sequencing (dideoxy method) principles and methods?
① is used nucleotide chain termination agent, dideoxynucleotide ddNTP termination
of DNA chain extension.
② available to a group of ddNTP at the end of the DNA fragments of varying lengths.
③ divided into four groups, each group in the reaction system by adding four kinds of
dNTP and a corresponding ddNTP.
④ get different lengths in order to dideoxy DNA fragment end.
⑤ separated by gel electrophoresis, from the bottom can be directly read out the DNA
sequence.
4. Natural plasmid artificial construct of the plasmid transformation mainly for what?
① adding a suitable selectable marker genes, usually antibiotic genes.
②increase or decrease the appropriate restriction sites to facilitate restructuring.
③ shorten the length of the truncated fragments unnecessary to increase the load.
④ change the replicon from the stringent becomes loose type, in order to increase the
copy number.
⑤ specific gene components to install.