BioSc 231
General Genetics
Exam 5
Name __________________________________
Multiple Choice. (2 points each)
_____ Which of the following is not an example of a vector used in cloning experiments?
A. plasmid
B. polytene chromosome
C. yeast artificial chromosome
D. cosmid
E. bacteriophage lambda
_____ To prepare clones representing expressed genes from a eukaryotic cell, you would mix total cellular mRNA with
A. reverse transcriptase
B. RNA polymerase
C. DNA polymerase
D. integrase
E. RNAse
_____ Enzyme that cleaves DNA at sequence-specific sites is called
A. DNA polymerase
B. ligase
C. restriction endonuclease
D. sticky ends
E. cDNA
_____ DNA termini with overhangs produced by endonuclease digestion are called
A. sticky ends
B. blunt ends
C. oligonucleotides
D. none of the above
_____Which enzyme functions to polymerize DNA from an RNA template?
A. DNA polymerase
B. RNA polymerase
C. Reverse transcriptase
D. Ligase
E. Endonuclease
_____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
_____An enzyme used to covalently join DNA segments to form recombinant DNA molecules is called a
A. Restriction endonuclease
B. 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
_____ 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
_____ cDNA is
A. chromosomal DNA which has been isolated from a donor organism.
B. complementary DNA that is generated by using reverse transcriptase to make DNA from mRNA.
C. cloned DNA that has been introduced into a cloning vector.
D. cut DNA that has been digested with a restriction endonuclease for use in a cloning experiment.
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?
(2 points) What is an “open reading frame” and how is it identified?
(2 pts) The restriction endonuclease HindIII (which cuts at the sequence AAGCTT) cuts the genome of the bacteriophage lambda
(approximately 50 kilobases in size) into 7 fragments. The enzyme RsaI (which cuts at the sequence GTAC) cuts the lambda genome
into 113 fragments. Explain the reason for the difference in the number of cleavage sites for these two enxymes.
(3 pts) Standard cloning vectors have three important features. Briefly explain the function of each of these features.
Origin of replication (Ori)
Antibiotic Resistance gene (AmpR)
Restriction endonuclease cleavage site
(2 pts) What is the purpose of using dideoxynucleotides in sequencing?
(1 pt) Oligonucleotide probes used in hybridization experiments such as Southern blots or for screening gene libraries are typically at
least 20 nucleotides in length. Briefly explain the reason why they need to be so long.
(2 pts) Name 2 applications of Polymerase chain reaction (PCR)
(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.
(6 points) You want to design an 21 nucleotide long oligonucleotide probe to identify a clone containing a new enzyme that you
purified. You determine that the amino terminal sequence of your enzyme is:
MAKEMYDAYGETANA
What should be the sequence of the oligonucleotide probe? Indicate redundancy by putting all possible nucleotides for a particular
position above or below the location of the redundancy.
(5 points) A researcher has discovered the gene in elves that makes them jolly (apparently Santa Claus is a mutant with multiple
copies of this gene). They would like to clone this gene to develop gene therapy for grumpy people. 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.
Bonus Questions
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.
Gene is married to Gert, who was previously married to Greg, now deceased. Greg and Gert conceived one child together and
adopted one child. Gene and Gert have also conceived one child. All members of Gert’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.
Gene and Gert’s conceived child
Child ____
Greg and Gert’s conceived child
Child ____
Greg and Gert’s adopted child
Child ____