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Genetics > TOP HAT EXAM 2 > Flashcards

TOP HAT EXAM 2 Flashcards

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1
Q

Which statement is true regarding negative supercoiled DNA?
A.
Negative supercoiled DNA is under-rotated and allows for easier strand separation during replication and transcription.

b
Negative supercoiled DNA is not usually seen in cells.

c
Negative supercoiled DNA has 10 base pairs per turn of its helix.

d
Negative supercoiled DNA carries more negative charges than does positive supercoiled DNA.

A

A.
Negative supercoiled DNA is under-rotated and allows for easier strand separation during replication and transcription.

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2
Q

A DNA molecule 300 bp long has 20 complete rotations. This DNA molecule is
a
positively supercoiled.

b
negatively supercoiled.

c
relaxed.

A

b
negatively supercoiled.

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3
Q

A DNA molecule 500 bp long has 50 complete rotations. This DNA molecule is _.
a
single stranded

b
positively supercoiled

c
negatively supercoiled

d
relaxed

A

d
relaxed

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4
Q

Barr Bodies are

a
Heterochromatin

b
Euchromatin

A

a
Heterochromatin

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5
Q

Heterochromatin is characterized by all of the following EXCEPT that it _.

a
is present all over the inactive X chromosomes in female mammals.

b
contains genes that are transcribed at high levels.

c
is present on most of the Y chromosomes of male mammals.

d
remains highly condensed throughout the cell cycle.

e
is present at centromeres and telomeres.

A

b
contains genes that are transcribed at high levels.

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6
Q

Genes that are transcriptionally active will _.

a
be less sensitive to DNase I digestion

b
be located in regions of relaxed chromatin

c
have more heavily methylated DNA

d
All of the above will occur

A

b
be located in regions of relaxed chromatin

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7
Q

If a piece of chromatin contained 200 copies of the histone H4, then how many nucleosomes would be present?

a
100

b
200

c
40

d
We cannot say. Histones are randomly placed throughout chromatin.

A

a
100

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8
Q

A novel organism has a genome complexed with three histone-like proteins. Nuclease digestion give bands of 700 bp, 1400bp and 2100bp. What is the likely explanation
a
700 bp of DNA wrap around each histone

b
The histones are different sizes and bind different lengths of DNA

c
The histone-like proteins don’t bind to DNA

d
None of the above

A

a
700 bp of DNA wrap around each histone (binds to about 200bp so 3 histone =600)

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9
Q

After the first round of replication, Meselson and Stahl saw only one DNA band of density intermediate to DNA containing only 15N or 14N. After this observation, which hypothesis for DNA replication could be eliminated?
a
Conservative

b
Semiconservative

c
Dispersive

d
Both a and c

A

a
Conservative

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10
Q

All DNA polymerases require a primer with a 3´ OH group to begin DNA synthesis. The primer is _.

a
a free DNA nucleotide

b
a short stretch of RNA nucleotides

c
a 3’ OH group that is part of the primase enzyme

d
All of the above

A

b
a short stretch of RNA nucleotides

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11
Q

DNA replication in eukaryotes differs from replication in prokaryotes in that _.

a
DNA replication in eukaryotes is conservative, whereas in prokaryotes it is semiconservative

b
eukaryotes have bidirectional replication from an origin, whereas in prokaryotes replication proceeds in one direction from an origin

c. eukaryotic chromosomes have many separate origins of replication, whereas prokaryotic chromosomes have a single origin of replication

d. linear eukaryotic chromosomes are replicated by a mechanism called theta replication, whereas circular prokaryotic chromosomes are replicated by the rolling-circle mechanism

A

c
eukaryotic chromosomes have many separate origins of replication, whereas prokaryotic chromosomes have a single origin of replication

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12
Q

Replication of eukaryotic chromosomes presents several challenges that are not found in prokaryotic cells. These challenges include all of the following EXCEPT
a. removal and reassembly of nucleosomes

b. eukaryotic DNA polymerases are, in general, much more error-prone

c. replication of chromosome ends

d. coordination of replication with the cell cycle

A

b. eukaryotic DNA polymerases are, in general, much more error-prone

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13
Q

A eukaryotic cell containing defective DNA polymerase α would have difficulty performing which of the following?
Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer.

a
relieving tension in the DNA due to supercoiling

b
creating an open replication fork in DNA by breaking hydrogen bonds

c
connecting Okazaki fragments

d
laying down an RNA primer to start DNA replication

A

D. laying down an RNA primer to start DNA replication

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14
Q

All of the following DNA-repair mechanisms use an undamaged complementary DNA strand as a template for replacing the excised nucleotides except for _
a
base-excision repair

b
nonhomologous end joining

c
mismatch repair

d
homologous recombination

e
nucleotide-excision repair

A

b
nonhomologous end joining
Your answer

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15
Q

Mismatch repair requires the ability to distinguish between template and newly synthesized DNA strands. How can E. coli distinguish between these two strands?
a
New DNA is methylated

b
Template DNA is phosphorylated

c
Template DNA is methylated

d
New DNA contains single-stranded binding proteins

A

c
Template DNA is methylated

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16
Q

Which of the following types of DNA repair would involve the enzyme AP endonuclease?
a
Mismatch repair

b
Base-excision repair

c
Nucleotide-excision repair

d
Homologous recombination

A

b
Base-excision repair

17
Q

When depurination of a nucleotide occurs, an apurinic site is created. A nucleotide with a/an __ base is typically inserted across from the apurinic site during DNA replication
a
adenine

b
cytosine

c
guanine

d
thymine

e
uracil

A

a. adenine

18
Q

The 3’-5’ exonuclease activity of DNA polymerase positions the correct nucleotide to be added to the 5’ end of the DNA molecule.
a
True

b
False

A

b. False

19
Q

Autosomal mutations are heritable.
a
True

b
False

A

a
True

20
Q

Which phrase describes the first step in the lytic cycle of bacteriophage?.

a
The phage attaches to the host cell and prepares to insert DNA.

b
The phage attaches to the host cell and secretes enzymes that kill the cell.

c
The phage inserts its genetic material into the DNA of the host cell

d
The phage DNA is replicated inside the target cell.

A

a
The phage attaches to the host cell and prepares to insert DNA.

21
Q

HIV is a retrovirus. How are retroviruses unique from other types of viruses?
a
They are easily transmitted across different species.

b
They use reverse transcriptase to make DNA from RNA.

c
They contain single-stranded RNA inside the capsid.

d
They have a viral envelope surrounding the capsid.

A

b
They use reverse transcriptase to make DNA from RNA.

22
Q

Influenza antigenicity can change rapidly by _.

a. mutation

b
reverse transcription

c
antigenic drift

d. antigenic shift

A

d
antigenic shift

23
Q

Match this terms iNVERSION, DUPLICATION, DELETIONS, POLYPLOIDY, TRANSLOCATION
A. increase the amount of genetic material in a particular chromosome
B. increase the amount of genetic material in all chromosomes
C. decrease the amount of genetic material in a particular chromosome
D. change the position of DNA sequences in a single chromosome without changing the amount of genetic material
E. move DNA from one chromosome to a nonhomologous chromosome

A

A. increase the amount of genetic material in a particular chromosome- DUPLICATION
B. increase the amount of genetic material in all chromosomes POLYPLOIDY
C. decrease the amount of genetic material in a particular chromosome DELETION
D. change the position of DNA sequences in a single chromosome without changing the amount of genetic material INVERSION
E. move DNA from one chromosome to a nonhomologous chromosome TRANSLOCATION

24
Q

What is the outcome of a Robertsonian translocation?

a
Two acrocentric chromosomes

b
One metacentric chromosome and one chromosome with two very short arms

c
One metacentric chromosome and one acrocentric chromosome

d
Two metacentric chromosomes

A

b
One metacentric chromosome and one chromosome with two very short arms

25
Q

Which is NOT a way that deletions can cause abnormal phenotypes?
a
If the centromere is deleted, then the whole chromosome could be lost during cell division.

b
Recessive mutations may be expressed if the wild-type allele is deleted, a phenomenon called pseudodominance.

c
Haploinsufficient genes can result because too much gene product is produceD

d
There may be an imbalance of gene products due to the lack of genetic information caused by the deletion.

e
All of the above.

A

c
Haploinsufficient genes can result because too much gene product is produced

26
Q

The expression of some genes is dependent upon their chromosomal position. Which kind of chromosome rearrangement would most likely cause a position-effect phenotype?
a
Deletion

b
Tandem duplication

c
Segmental duplication

d
Inversion

e
All of the above

A

d
Inversion

27
Q

Which is NOT an affect of chromosomal translocations?

a
Translocated genes may become under the control of different regulatory sequences.

b
Translocations can cause regions of the chromosome to be duplicated.

c
Translocation breaks can disrupt existing gene function.

d
Translocations can affect the number of chromosomes found in species through evolution.

A

b
Translocations can cause regions of the chromosome to be duplicated.

28
Q

A diploid organism has 2n = 36 chromosomes. How many chromosomes will be found in a trisomic member of this species?

A

37

29
Q

Trisomy and monosomy can be a product of nondisjunction in _.
a
meiosis I

b
meiosis II

c
mitosis

d
Both a and b

e
All of the above

A

e
All of the above

30
Q

One species has 32 chromosomes and another species has 24 chromosomes. In an allotriploid of these two species, how many chromosomes would there be?
a. 44 or 40

b. 56

c. 84

d. 28

e. 48 or 36

A

a. 44 or 40

31
Q

Suppose that Hershey and Chase found that phage ghosts contained 32P label but the label was absent from infected E. coli. Furthermore, suppose they found 35S lacking in the ghosts and present in the infected E. coli. They would have concluded _
a
that protein was the genetic material in phage

b
that DNA was the genetic material in phage

c
that somehow the radioactivity prevented DNA from getting into E. coli

d
that protein and DNA together made up the genetic material

e
None of the above

A

a
that protein was the genetic material in phage

32
Q

In humans, 20% of bases in DNA are cytosine (C). What percentage of the bases are expected to be thymine (T)?

a
20%

b
25%

c
30%

d
40%

e
80%

A

c
30%

33
Q

How many nanometers long is a 1000 base pair strand of DNA

A

340

34
Q

You are conducting an experiment where you must denature a strand of DNA that is very G-C rich. How would the melting temperature (Tm) of your DNA sample differ from that of a sample that is very A-T rich?

a
The Tm is irrelevant to denaturation.

b
The Tm is only important for RNA.

c
The Tm of your sample would be the same as that of a sample that is very A-T rich.

d
The Tm of your sample would be less than that of a sample that is very A-T rich.

e
The Tm of your sample would be greater than that of a sample that is very A-T rich.

A

e
The Tm of your sample would be greater than that of a sample that is very A-T rich.

Genetics (20 decks)

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