Test 3

Question 1

In the context of early studies of molecular biolofy performed to decipher the properties and the identity of the genetic material, Griffith et al. demonstrated which of the following?

A. The property of transformation or uptake of genetic material in bacteria
B. The chemical nature of the transforming material in bacteria
C. The chemical nature of the genetic material in T2 bacteriophage
D. All of the above are correct
E. A. and B.

Answer 1

A. The property of transformation or uptake of genetic material in bacteria

Question 2

A nucleoside is defined as ?
A. A sugar linked to a base
B. A sugar linked to a phosphate group
C. A base linked to a phosphate group
D. A sugar linked to a base linked to a phosphate group
E. None of the above

Answer 2

A. A sugar linked to a base

Question 3

At the replication fork, _____ catalyzes the synthesis of DNA.

Answer 3

DNA polymerase

Question 4

Ahead of the replication fork, ____ diminishes the tension that is created as the double helix supercoils.

Answer 4

Gyrase

Question 5

______ is complexed with helicase and creates short RNA primers

Answer 5

Primase

Question 6

_____ breaks the hydogen bonds between the bases at the replication fork

Answer 6

Helicase

Question 7

The replication of DNA proceeds in what direction?
A. 3' to 5'
B. 5' to 5'
C. 3' to 3'
D. 5' to 3'
E. None of the above

Answer 7

D. 5’ to 3’

Question 8

Eukaryotic cells use the same DNA polymerase to replicate mitochondrial DNA and nuclear DNA.
A. True
B. false
C. Sometimes
D. Unknown

Answer 8

B. false

Question 9

In the context of DNA recombination, crossing over takes place:
A. Before DNA synthesis, resulting in all the products that are recombinants
B. During DNA synthesis, resulting in products that are recombinant and nonrecombinant
C. After synthesis, resulting in products that are recombinant and nonrecombinant
D. B. and C.
E. All of the above

Answer 9

C. After synthesis, resulting in products that are recombinant and nonrecombinant

Question 10

Eukaryotic chromosomes require an RNA primer to initiate all new DNA synthesis. However, this poses a problem’, eukaryotes have unique features at the end of their ____ chomosomes called telomeres that recruit a specialized DNA polymerase called telomerase. Telomerase is composed of both protein and ____ that extends the ends of the chomosome, thus solving the ‘end replication problem’.

Answer 10

Linear

RNA

Question 11

Acetylation of the histone proteins would have which effect on its interaction with DNA?

A. The DNA would bind more tightly to the histones
B. The DNA would loosen its interaction with the histones
C. The DNA would become more accessible
D. The DNA would become less accessible
E. B. and C.

Answer 11

E. B. and C.

Question 12

Methylation of the histone proteins would have which effect on its interaction with DNA?

A. The DNA would bind more tightly to the histones
B. The DNA would loosen its interaction with the histones
C. The DNA would become more accessible
D. The DNA would become less accessible
E. B. and C.

Answer 12

D. The DNA would become less accessible

Question 13

Deacetylation of the histone proteins would have which effect on its interaction with DNA?

A. The DNA would bind more tightly to the histones
B. The DNA would loosen its interaction with the histones
C. The DNA would become more accessible
D. The DNA would become less accessible
E. A. and D.

Answer 13

E. A. and D.

Question 14

In the context of eukaryotic transcription, there are several proteins that come together to form the ‘basal transcription apparatus’. What is the role of the basal transcription machinery?

A. To recognize the transcription start site
B. To bind to the TATA box with the promoter
C. To stabilize the interaction between the proteins and the DNA
D. To unwind the DNA so that it may be used as a template
E. All of the above

Answer 14

E. All of the above

Question 15

There is one profound difference between replication and transcription that reflects the different purposes served by these distinct molecular processes - what is it?

A. Transcription selectively copies certain parts of the genome
B. Replication selectively copies certain parts of the genome
C. Transcription randomly copies certain parts of the genome
D. Replication randomly copies certain parts of the genome
E. There are no difference between replication and transcription.

Answer 15

A. Transcription selectively copies certain parts of the genome

Question 16

Which of the following is not required for transcription?

A. Ribonucleotides
B. RNA primers
C. DNA template
D. RNA polymerase
E. All of the above are required

Answer 16

B. RNA primers

Question 17

Bacterial cells posses one RNA polymerase that is a large, multimeric enzyme composed of five subunits that make up the core enzyme. What is the role of the subunit called sigma factor (σ)?
A, Promiscuity
B. Selectivity
C. Precision
D. Specificity
E. None of the above

Answer 17

D. Specificity

Question 18

In prokaryotes, rho-independant transcription termination depends on a secondary structure formed in - ?

A. The RNA polymerase that is transcribing the gene
B. The DNA template
C. The RNA that is being transcribed
D. A protein factor that binds to RNA polymerase
E. A protein factor that binds to the RNA that is being transcribed

Answer 18

C. The RNA that is being transcribed

Question 19

Which of the following human cells contain a gene that specifies eye color?

A. Cells in the eye
B. Cells in the heart
C. Gametes
D. Cells in the eye and gametes
E. All of the above

Answer 19

E. All of the above

Question 20

How many copies of the H1 histone protein would be found in chromatin containing 60 nucleosomes?

A. 15
B. 30
C. 60
D. 120
E. 240

Answer 20

C. 60

Question 21

_____ undergoes the normal process of condensation and decondensation in the cell cycle, represents the majority of chomosomal material, is where most transcription takes place, and is considered to be ‘active DNA’.

A. Heterochromatin
B. Euchromatin
C. All chromatin
D. None of the above

Answer 21

B. Euchromatin

Question 22

Suppose that a single DNA base change of an A to a T occurs and is copied during replication. Is this change necessarily a mutation?
A. Yes, it is a change in the DNA sequence.
B. Yes, if the base change occurs in a gamete (sperm or egg cell); otherwise no.
C. Yes, if the base change occurs in the coding part of a gene; otherwise no.
D. Yes, if the base change occurs in the coding part of a gene and alters the amino acid sequence of a protein; otherwise no.
E. Yes, if the base change alters the appearance of the organism (phenotype); otherwise
no.

Answer 22

A. Yes, it is a change in the DNA sequence.

Question 23

In a population of genetically identical mice, you discover two independent mutant strains in which all of the animals have epileptic seizures. In both strains, you know that the epileptic seizures are due to a single DNA mutation. You cross a mutant mouse from one strain to a mutant mouse from the second strain and find out that none of their offspring undergo spontaneous seizures. From this experiment you would conclude that the two mutant strains of mice most likely have mutations in:

A. the same DNA base (A, T, C, or G) within a particular gene.
B. the same gene, but not necessarily the same DNA base.
C. Two different genes.

Answer 23

C. Two different genes.

Question 24

The MLH1 gene is important in colorectal cancer.  This gene is located on chromosome 3, and four different alleles of the gene have been identified in humans.  The maximum number of alleles a single normal individual can have is:
	A. 1
	B. 2
	C. 3
	D. 4

Answer 24

B. 2

Question 25

Use the following mRNA codon key as needed to answer the next two questions: 
GCC	Alanine
AAU	Asparagine
CCU	Proline
GGA	Glycine
UGG	Tryptophan
UGA	“Stop” (no amino acid)
GAA	Glutamic acid
GAG	Glutamic acid
AGG	Arginine 
CCC	Proline
CAU	Histidine

The following DNA sequence (coding strand) occurs near the middle of the coding region of a gene.

DNA
50 55 60 65
5’—A A T G A A T G G G A G C C T G A A G G A G –-3’

The corresponding mRNA sequence is shown below. Note that the coding strand of DNA has the same sequence as the mRNA, except that there are U’s in the mRNA where there are T’s in the DNA. The first triplet of nucleotides AAU (underlined) is in frame for coding, and encodes Asparagine as the codon table above indicates.

mRNA
50 55 60 65
5’—A A U G A A U G G G A G C C U G A A G G A G –-3’

Which of the following DNA mutations is almost certain to result in a shorter than normal mRNA?

a) A→G at position 50
b) G→A at position 53
c) C→A at position 58
d) None of the above

Answer 25

d) None of the above

Question 26

For the same DNA sequence, which of the following DNA mutations is almost certain to result in a shorter than normal protein?

a) T→C at position 59
b) A→G at position 61
c) Insertion of a G after the G at position 54
d) None of the above

Answer 26

c) Insertion of a G after the G at position 54

Question 27

You have identified a previously unknown human gene that appears to have a role in autism. It is similar enough in DNA sequence to a known mouse gene that you believe the two genes may be evolutionarily related. You determine and compare the DNA sequences, the predicted mRNA sequences, and the predicted amino acid sequences corresponding to the two genes. You would expect to find the greatest sequence similarity from comparisons of the two:

a) DNA sequences.
b) mRNA sequences.
c) amino acid sequences.
d) All three comparisons are likely to show the same degree of sequence similarity.

Answer 27

c) amino acid sequences.

Question 28

You are interested in studying a gene called CFTR because mutations in this gene in humans cause cystic fibrosis. You have made a line of mice that lack the mouse CFTR gene. These mice are unable to clear bacteria from their lungs, so they get lung disease. You put a normal human CFTR gene into some of these mice and discover that the mice with the human gene are able to clear bacteria from their lungs and no longer get lung disease. From this experiment, you can conclude that:

a) The DNA sequences of the mouse CFTR gene and human CFTR gene are identical.
b) The amino acid sequences of the mouse CFTR protein and the human CFTR protein are identical.
c) The mouse CFTR gene and human CFTR gene both encode proteins that are similar in function.
d) Both answers b) and c)
e) All of the above

Answer 28

c) The mouse CFTR gene and human CFTR gene both encode proteins that are similar in function.

Question 29

A collection of clones containing DNA fragments that have been produced by reverse transcription of cellular mRNA

Answer 29

cDNA library

Question 30

An ordered set of DNA fragments fixed to a solid support, which serve as probes to detect the presence of complimentary sequences; often used to assess the expression of genes in various tissues and under different conditions.

Answer 30

microarray

Question 31

A collection of clones containing DNA fragments that consist of an entire genome of an organism

Answer 31

Genomic library

Question 32

The molecular genetic technique by which a short DNA or RNA sequence is amplified by means of oligonucleotide primers used in repeated cycles of in vitro DNA synthesis

Answer 32

PCR

Question 33

The molecular genetic technique by which DNA is transferred to a membrane and hybridized with gene-specific probes to detect a specific DNA amongst a heterogeneous mixture of DNA

Answer 33

Southern blot

Question 34

If a DNA molecule is 40% cytosine (C) what is the percentage of guanine (G)?

A. 20%
B. 40%
C. 60%
D. 80%
E. unknown

Answer 34

B. 40%

Question 35

If a DNA molecule of 80 base pairs contains 45 adenosine bases (A), how many guanine (G) bases will it have?

A. 15
B. 35
C. 45
D. 90
E. unknown

Answer 35

B. 35

Question 36

Which of the following statements below does not accuratley describe a difference between DNA and RNA?

A. RNA molecules are usually single-stranded
B. The bases in RNA contain uracil instead of thymine
C. The sugar in RNA is deoxyribose instead of ribose
D. RNA molecules often take on secondary or tertiary structures for proper function
E. All of the above

Answer 36

C. The sugar in RNA is deoxyribose instead of ribose

Question 37

siRNAs and miRNAs are needed in which process?

A. Transcription
B. Translation
C. Replication
D. RNA splicing
E. RNA interference

Answer 37

E. RNA interference