Multiple Choice Questions
1. DNA cloning: the basics
Page: 307Difficulty: 1Ans: C
A) act at the membrane to restrict the passage of certain molecules into the cell. B) are highly specialized ribonucleases that degrade mRNA soon after its synthesis. C) are sequence-specific DNA endonucleases.
D) are very specific proteases that cleave peptides at only certain sequences. E) catalyze the addition of a certain amino acid to a specific tRNA.
2. DNA cloning: the basics
Pages: 307-308Difficulty: 2Ans: B
The biological role of restriction enzymes is to:
A) aid recombinant DNA research.
B) degrade foreign DNA that enters a bacterium.
C) make bacteria resistant to antibiotics.
D) restrict the damage to DNA by ultraviolet light.
E) restrict the size of DNA in certain bacteria.
3. DNA cloning: the basics
Page: 308Difficulty: 1Ans: A
The size of the DNA region specifically recognized by type II restriction enzymes is typically:
A) 4 to 6 base pairs.
B) 10 to 15 base pairs.
C) 50 to 60 base pairs.
D) 200 to 300 base pairs.
E) about the size of an average gene.
4. DNA cloning: the basics
Page: 308Difficulty: 2Ans: D
Which of the following statements about type II restriction enzymes is false?
A) Many make staggered (off-center) cuts within their recognition sequences. B) Some cut DNA to generate blunt ends.
C) They are part of a bacterial defense system in which foreign DNA is cleaved. D) They cleave and ligate DNA.
E) They cleave DNA only at recognition sequences specific to a given restriction enzyme.
5. DNA cloning: the basics
Page: 308Difficulty: 2Ans: C
Certain restriction enzymes produce cohesive (sticky) ends. This means that they:
A) cut both DNA strands at the same base pair.
B) cut in regions of high GC content, leaving ends that can form more hydrogen bonds than ends of high AT content. C) make a staggered double-strand cut, leaving ends with a few nucleotides of single-stranded DNA protruding. D) make ends that can anneal to cohesive ends generated by any other restriction enzyme. E) stick tightly to the ends of the DNA they have cut.
6. DNA cloning: the basics
Page: 311Difficulty: 3Ans: E
In the laboratory, recombinant plasmids are commonly introduced into bacterial cells by:
A) electrophoresis – a gentle low-voltage gradient draws the DNA into the cell. B) infection with a bacteriophage that carries the plasmid. C) microinjection.
D) mixing plasmids with an extract of broken cells.
E) transformation – heat shock of the cells incubated with plasmid DNA in the presence of CaCl2.
7. DNA cloning: the basics
Page: 311Difficulty: 2Ans: B
The E. coli recombinant plasmid pBR322 has been widely utilized in genetic engineering experiments. pBR322 has all of the following features except:
A) a number of conveniently located recognition sites for restriction enzymes. B) a number of palindromic sequences near the EcoRI site, which permit the plasmid to assume a conformation that protects newly inserted DNA from nuclease degradation. C) a replication origin, which permits it to replicate autonomously. D) resistance to two different antibiotics, which permits rapid screening for recombinant plasmids containing foreign DNA. E) small overall size, which facilitates entry of the plasmid into host cells.
8. DNA cloning: the basics
Page: 311Difficulty: 2Ans: E
Which of the following statements regarding plasmid cloning vectors is correct?
A) Circular plasmids do not require an origin of replication to be propagated in E. coli. B) Foreign DNA fragments up to 45,000 base pairs can be cloned in a typical plasmid. C) Plasmids do not need to contain genes that confer resistance...