BioSc 231
General Genetics
Exam 5
Name __________________________________
Multiple Choice. (2 points each)
_____ For gene cloning, a geneticist digests DNA with ___ an enzyme that cleaves DNA at sequence-specific sites.
A. DNA polymerase
B. ligase
C. restriction endonuclease
D. sticky ends
E. cDNA
_____ Certain endonucleases cut DNA and leave DNA termini without overhangs which are called
A. cohesive termini
B. sticky ends
C. blunt ends
D. oligonucleotides
E. none of the above
_____ If you wanted to clone the largest DNA fragments possible, which vector element would you use?
A. plasmid
B. bacteriophage lambda
C. YAC
D. cosmid
_____ An enzyme found in retroviruses (like HIV) that can be used to prepare DNA fragments from mRNA is called ___.
A. reverse transcriptase
B. RNA polymerase
C. DNA polymerase
D. integrase
E. RNAse
_____ After combining DNA fragments in a cloning experiment, ___ is used to covalently joined the DNA segments.
A. Restriction endonuclease
B. DNA Ligase
C. Reverse transcriptase
D. DNA polymerase
E. Helicase
_____Plasmids used in vitro to clone foreign DNA fragments are called
A. Transgenic
B. cDNA
C. Clones
D. Vectors
E. Conjugants
_____The bacterium used as the model for genetic recombination and engineering in plants is
A. Salmonella typhimurium
B. Coleus
C. Torulopsis glabrata
D. Agrobacterium tumefaciens
E. Arabidopsis
_____Genetic engineering of eukaryotic cells is accomplished using
A. Direct injection of DNA into fertilized eggs
B. Retroviral vectors
C. Embryonic stem cells
D. Gene targeting
E. All of the above
_____ Differing sizes of restriction fragments produced from the alleles of a gene constitute
A. a southern blot
B. an allozyme
C. identification of a gene
D. a restriction fragment length polymorphism
_____ Which of the following is NOT necessary in order for a population to maintain Hardy-Weinberg equilibrium?
A. random mating
B. high rate of migration
C. large population size
D. allele frequencies are the same in males and females
_____ In a population in Hardy-Weinberg equilibrium the frequency of the allele for an inherited genetic disease is 0.01. What
percentage of the population is homozygous for this allele?
A. 0.01%
B. 1%
C. 0.09%
D. 99%
E. 0.01%
_____ In a population with two alleles, B and b, the frequency of b is 0.34. What would be the frequency of the heterozygotes,
assuming Hardy-Weinberg equilibrium?
A. 0.34
B. 0.66
C. 0.12
D. 0.88
E. 0.45
_____ Which of the following processes does not contribute to changing allele frequencies in populations?
A. mutation
B. inbreeding
C. migration
D. natural selection
E. genetic drift
_____ Enzyme that cleaves DNA at sequence-specific sites is called
A. DNA polymerase
B. ligase
C. restriction endonuclease
D. sticky ends
_____ A restriction fragment containing a specific gene of interest can be identified by gel electrophoresis followed by transferring the
DNA to a membrane as a solid support matrix using a procedure called
A. a Southern blot
B. an allozyme
C. identification of a gene
D. a restriction fragment length polymorphism
Short Answer (variable points)
(2 points) Many new cloning vectors have a DNA sequence called a polylinker (or multicloning site) that contains the recognition
sequences for many restriction endonucleases. What is the purpose of this region?
(6 points) You want to design an oligonucleotide probe to identify a clone containing a new enzyme that you purified. You determine
that the amino terminal sequence of your enzyme is:
MNDHYWIK
What should be the sequence of the oligonucleotide probe? Indicate redundancy by putting all possible nucleotides for a particular
position in parenthesis.
(4 points) In a restriction mapping experiment you cleave a DNA fragment containing the MNR gene with the individual restriction
enzymes XbaI, HindIII, and BamHI individually and in combination with one another and obtain restriction products of the sizes
shown below:
Enzyme(s) used
Sizes of DNA fragments produced (bp)
HindIII, BamHI, XbaI
1750, 1500, 1250, 500
HindIII, BamHI
2250, 1500, 1250
HindIII, XbaI
3000, 1500, 500
BamHI, XbaI
2000, 1750, 1250
HindIII
3500, 1500
BamHI
3750, 1250
XbaI
3000, 2000
Using the above data, make a restriction map of the MNR gene fragment indicating distances between adjacent restriction sites.
(6 points) Fred is married to Helen, who was previously married to George, now deceased. George and Helen conceived one child
together and adopted one child. Fred and Helen have also conceived one child. All members of Helen’s current family have had
DNA fingerprinting done at a single VNTR locus. Unfortunately, the sheet that identified each child has been misplaced. Identify
which fingerprint in each lane (in lanes 5, 6, and 7) correspond to each child.
Fred and Helen’s conceived child
Child ____
George and Helen’s conceived child
Child ____
George and Helen’s adopted child
Child ____
(5 points) A researcher has discovered a gene that makes fireflies glow and would like to clone the gene and put it into a poinsettia
plant to make glow in the dark poinsettias. Describe the “basic steps” involved in cloning the gene.
(5 points) To the right is a hypothetical autoradiogram of a dideoxy sequencing gel. What is the sequence of the gene fragment? Be
sure to label the 5' and 3' ends.
(2 points) PCR has become a standard technique in diagnosis, criminal investigations and paternity testing. What are the basic
ingredients of a PCR reaction that enable investigators to amplify a specific fragment of DNA.
Bonus Question
When you go home for Christmas break, someone in your family is bound to ask you what you learned in school this semester.
Describe something you learned in this class that you think would be worthy of using as a response to this question