Biology 212 Exam 2 Questions and
Answers
Knockout mice have been genetically altered to knock out specific genes. How are
these mice most often used in research? - ANSWER-to determine the role of
proteins coded for by those genes that are knocked out
In the Morse code, a series of dots and dashes code for letters of the alphabet. How
is this analogous to the genetic code? - ANSWER-The bases of DNA code for the
more complex amino acid sequence of the proteins in cells.
How does the simple primary and secondary structure of DNA hold the information
needed to code for the many features of multicellular organisms? - ANSWER-The
base sequence of DNA carries the information needed to code for proteins.
Given the locally unwound double strand above, in which direction does the RNA
polymerase move while transcribing DNA? - ANSWER-3' → 5' along the template
DNA strand
What does it mean when we say the genetic code is redundant? - ANSWER-More
than one codon can specify the addition of the same amino acid.
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The
corresponding codon for the mRNA transcribed is _____. - ANSWER-3' UCA 5'
The genetic code is essentially the same for all organisms. From this, one can
logically assume which of the following? - ANSWER-A gene from an organism can
theoretically be expressed by any other organism.
Which of the following observations may have resulted in the hypothesis that a
codon is made up of three bases? - ANSWER-A codon of three bases in length, from
four different bases, would code for a maximum of sixty-four different amino acids.
Why might a point mutation in DNA make a difference in the level of a protein's
activity? - ANSWER-It might substitute a different amino acid in the active site.
Which of the following DNA mutations is most likely to damage the protein it
specifies? - ANSWER-a base-pair deletion
Which small-scale mutation would be most likely to have a catastrophic effect on the
functioning of a protein? - ANSWER-a base deletion near the start of a gene
The most commonly occurring mutation in people with cystic fibrosis is a deletion of
a single codon. This results in _____. - ANSWER-a polypeptide missing an amino
acid
, You want to engineer a eukaryotic gene into bacterial colony and have it expressed.
What must be included in addition to the coding exons of the gene? - ANSWER-a
bacterial promoter sequence
David Pribnow studied the base sequences of promoters in bacteria and bacterial
viruses. He found two conserved regions in these promoters (the -10 box and the -35
box). These two regions of the promoter _____. - ANSWER-bind the sigma subunit
that is associated with RNA polymerase
During elongation, RNA polymerase has three prominent channels, or grooves.
These channels provide sites for all of the following EXCEPT _____. - ANSWER-a
site for the exit of the diphosphates removed from the nucleotide triphosphates
Put the following events of bacterial transcription in chronological order.
1. Sigma binds to the promoter region.
2. The double helix of DNA is unwound, breaking hydrogen bonds between
complementary strands.
3. Sigma binds to RNA polymerase.
4. Sigma is released.
5. Transcription begins. - ANSWER-3, 1, 2, 5, 4
In an experimental situation, a student researcher inserts an mRNA molecule into a
eukaryotic cell after she has removed its 5' cap and poly-A tail. Which of the
following would you expect her to find? - ANSWER-The molecule is digested by
enzymes because it is not protected at the 5' end.
Suppose that an induced mutation removes most of the 5' end of the 5' UTR of an
mRNA. What is most likely to happen? - ANSWER-Removal of the 5' UTR also
removes the 5' cap and the mRNA will quickly degrade.
As scientists were unraveling the mysteries associated with transcription and
translation in eukaryotes, they discovered there was not a one-to-one
correspondence between the nucleotide sequence of a gene and the base sequence
of the mRNA it codes for. They proposed the genes-in-pieces hypothesis. How can
the genes-in-pieces hypothesis be explained? - ANSWER-Introns are noncoding
segments of DNA that are present in the initial transcript, but are removed by
splicing.
Some viruses can be crystallized and their structures analyzed. One such virus is
yellow mottle virus, which infects beans. This virus has a single-stranded RNA
genome containing about 6300 nucleotides. Its capsid is 25-30 nm in diameter and
contains 180 identical capsomeres.
If the yellow mottle virus begins its infection of a cell by using its genome as mRNA,
which of the following would you expect to be able to measure? - ANSWER-
translation rate
There should be a strong positive correlation between the rate of protein synthesis
and _____. - ANSWER-the number of ribosomes
Answers
Knockout mice have been genetically altered to knock out specific genes. How are
these mice most often used in research? - ANSWER-to determine the role of
proteins coded for by those genes that are knocked out
In the Morse code, a series of dots and dashes code for letters of the alphabet. How
is this analogous to the genetic code? - ANSWER-The bases of DNA code for the
more complex amino acid sequence of the proteins in cells.
How does the simple primary and secondary structure of DNA hold the information
needed to code for the many features of multicellular organisms? - ANSWER-The
base sequence of DNA carries the information needed to code for proteins.
Given the locally unwound double strand above, in which direction does the RNA
polymerase move while transcribing DNA? - ANSWER-3' → 5' along the template
DNA strand
What does it mean when we say the genetic code is redundant? - ANSWER-More
than one codon can specify the addition of the same amino acid.
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The
corresponding codon for the mRNA transcribed is _____. - ANSWER-3' UCA 5'
The genetic code is essentially the same for all organisms. From this, one can
logically assume which of the following? - ANSWER-A gene from an organism can
theoretically be expressed by any other organism.
Which of the following observations may have resulted in the hypothesis that a
codon is made up of three bases? - ANSWER-A codon of three bases in length, from
four different bases, would code for a maximum of sixty-four different amino acids.
Why might a point mutation in DNA make a difference in the level of a protein's
activity? - ANSWER-It might substitute a different amino acid in the active site.
Which of the following DNA mutations is most likely to damage the protein it
specifies? - ANSWER-a base-pair deletion
Which small-scale mutation would be most likely to have a catastrophic effect on the
functioning of a protein? - ANSWER-a base deletion near the start of a gene
The most commonly occurring mutation in people with cystic fibrosis is a deletion of
a single codon. This results in _____. - ANSWER-a polypeptide missing an amino
acid
, You want to engineer a eukaryotic gene into bacterial colony and have it expressed.
What must be included in addition to the coding exons of the gene? - ANSWER-a
bacterial promoter sequence
David Pribnow studied the base sequences of promoters in bacteria and bacterial
viruses. He found two conserved regions in these promoters (the -10 box and the -35
box). These two regions of the promoter _____. - ANSWER-bind the sigma subunit
that is associated with RNA polymerase
During elongation, RNA polymerase has three prominent channels, or grooves.
These channels provide sites for all of the following EXCEPT _____. - ANSWER-a
site for the exit of the diphosphates removed from the nucleotide triphosphates
Put the following events of bacterial transcription in chronological order.
1. Sigma binds to the promoter region.
2. The double helix of DNA is unwound, breaking hydrogen bonds between
complementary strands.
3. Sigma binds to RNA polymerase.
4. Sigma is released.
5. Transcription begins. - ANSWER-3, 1, 2, 5, 4
In an experimental situation, a student researcher inserts an mRNA molecule into a
eukaryotic cell after she has removed its 5' cap and poly-A tail. Which of the
following would you expect her to find? - ANSWER-The molecule is digested by
enzymes because it is not protected at the 5' end.
Suppose that an induced mutation removes most of the 5' end of the 5' UTR of an
mRNA. What is most likely to happen? - ANSWER-Removal of the 5' UTR also
removes the 5' cap and the mRNA will quickly degrade.
As scientists were unraveling the mysteries associated with transcription and
translation in eukaryotes, they discovered there was not a one-to-one
correspondence between the nucleotide sequence of a gene and the base sequence
of the mRNA it codes for. They proposed the genes-in-pieces hypothesis. How can
the genes-in-pieces hypothesis be explained? - ANSWER-Introns are noncoding
segments of DNA that are present in the initial transcript, but are removed by
splicing.
Some viruses can be crystallized and their structures analyzed. One such virus is
yellow mottle virus, which infects beans. This virus has a single-stranded RNA
genome containing about 6300 nucleotides. Its capsid is 25-30 nm in diameter and
contains 180 identical capsomeres.
If the yellow mottle virus begins its infection of a cell by using its genome as mRNA,
which of the following would you expect to be able to measure? - ANSWER-
translation rate
There should be a strong positive correlation between the rate of protein synthesis
and _____. - ANSWER-the number of ribosomes
