Download Exam II Review Questions

Exam II Review:
Sample Questions
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Safwan Elkhatib
BIO 212 (6)
Coffman
02/24/2014
Choose the list of three terms that correctly fill the blanks in the
following sentence:
The molecules illustrated here are ________________________ that combine with
_________________________ and with a ___________________ group to form
monomers that can combine to make DNA.
a.
b.
c.
d.
pyrimidines, ribose, amino
purines, ribose, phosphate
purines, deoxyribose, phosphate
pyrimidines, deoxyribose, ATP
When Hershey/Chase performed phage infection experiments, what compounds did they
use to label and detect DNA and protein?
a. 35S was used to label DNA, and 32P was used to label protein.
b. 35S was used to label protein, and 32P was used to label DNA.
Hydrogen bonding between nitrogenous bases is essential for correct
replication of DNA. Which of the following base pairs forms two hydrogen
bonds in DNA?
a.
b.
c.
d.
Adenine
Adenine
Adenine
Adenine
–
-
Guanine
Cytosine
Thymine
Adenine
The structural feature that allows near-perfect copying of DNA molecules is
a. their sugar-phosphate backbone.
b. the capability of its nitrogenous bases to form specific hydrogen
bonds that lead to matching of specific pairs of nucleotides.
c. disulfide bonds that hold the two helixes together.
d. the three-component (base, sugar, and phosphate) structure of the
nucleotides, because all three must be matched to make a perfect copy.
In your body, the most important function of ribonucleic acid (RNA) is to
a. transmit genetic information to offspring.
b. direct the synthesis of protein.
c. serve as a template for the synthesis of a complementary copy, thus
ensuring genetic continuity.
d. act as a template directing the synthesis of DNA.
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The two strands making up the DNA double helix molecule
a. cannot be separated.
b. contain ribose and deoxyribose in opposite strands.
c. are held together by hydrogen bonds.
d. are attached via ester bonds between phosphates that hold the
strands together.
In the double helix structure of nucleic acids, cytosine hydrogen-bonds to
a.
b.
c.
d.
deoxyribose.
adenine.
thymine.
guanine.
The pyrimidine bases in DNA are—
a. Cytosine, thymine and uracil
b. Adenine and guanine
c. Cytosine and thymine
d. Thymine, guanine and cytosine
e. Adenine, uracil and guanine
The purine bases in DNA are—
a. Cytosine, thymine and uracil
b. Adenine and guanine
c. Cytosine and thymine
d. Thymine, guanine and cytosine
e. Adenine, uracil and guanine
Nitrogen comes in a common light form (14N) and a rare heavy form (15N). In 1958,
Matthew Meselson and Franklin Stahl grew E.coli in medium with only 15N and then
switched to medium with only 14N. They collected samples after each generation, isolated
DNA, and subjected it to centrifugation to differentiate between DNA labeled with the
common light form (14N) and the rare heavy form (15N). Original parental strands would
contain 15N while newly made strands would contain 14N.
How many bands of DNA would you expect to see in the cesium gradient above after 3
generations if the mechanism of DNA replication was semi-conservative?
a. 1 band that is half heavy
b. 2 bands, one is light and the other half heavy
c. 3 bands, one is heavy, one is half-heavy, and one is light
d. 2 bands, one is heavy and one is light
Nitrogen comes in a common light form (14N) and a rare heavy form (15N). In 1958,
Matthew Meselson and Franklin Stahl grew E.coli in medium with only 15N and then
switched to medium with only 14N. They collected samples after each generation, isolated
DNA, and subjected it to centrifugation to differentiate between DNA labeled with the
common light form (14N) and the rare heavy form (15N). Original parental strands would
contain 15N while newly made strands would contain 14N.
How many bands of DNA would you expect to see in the cesium gradient above after 3
generations if the mechanism of DNA replication was conservative?
a. 1 band that is half heavy
b. 2 bands, one is heavy and the other half heavy
c. 3 bands, one is heavy, one is half-heavy, and one is light
d. 2 bands, one is heavy and one is light
Nitrogen comes in a common light form (14N) and a rare heavy form (15N). In 1958,
Matthew Meselson and Franklin Stahl grew E.coli in medium with only 15N and then
switched to medium with only 14N. They collected samples after each generation, isolated
DNA, and subjected it to centrifugation to differentiate between DNA labeled with the
common light form (14N) and the rare heavy form (15N). Original parental strands would
contain 15N while newly made strands would contain 14N.
How many bands of DNA would you expect to see in the cesium gradient above after 3
generations if the mechanism of DNA replication was dispersive?
a. 1 band that is a mixture of heavy and light DNA
b. 2 bands, one is heavy and the other half heavy
c. 3 bands, one is heavy, one is half-heavy, and one is light
d. 2 bands, one is heavy and one is light
Which of the four structures labeled A, B, C and D in the figure is best
described as a nucleotide?
a.
b.
c.
d.
A
B
C
D
Which of the following is the best description of the class of molecules
known as nucleotides?
a. a nitrogenous base linked to a phosphate group
b. a nitrogenous base linked to a pentose (5 carbon) sugar
c. a molecule including a nitrogenous base, a pentose (5 carbon) sugar
and a phosphate group
d. a phosphate group linked to an adenine or uracil
e. a pentose sugar linked to a purine or pyrimidine
What is the function of helicase during DNA replication?
a. It separates the two strands of the double helix.
b. It relieves the overwinding of DNA ahead of the replication fork due to DNA
strand separation.
c. It synthesizes the RNA primers used to initiate DNA replication.
d. It joins the Okazaki fragments together.
What is the function of topoisomerase during DNA replication?
a. It separates the two strands of the double helix.
b. It relieves the overwinding of DNA ahead of the replication fork due to DNA
strand separation.
c. It synthesizes the RNA primers used to initiate DNA replication.
d. It joins the Okazaki fragments together.
What is the function of primase during DNA replication?
a. It separates the two strands of the double helix.
b. It relieves the overwinding of DNA ahead of the replication fork due to DNA
strand separation.
c. It synthesizes the RNA primers used to initiate DNA replication.
d. It joins the Okazaki fragments together.
What is the function of ligase during DNA replication?
a. It separates the two strands of the double helix.
b. It relieves the overwinding of DNA ahead of the replication fork due to DNA
strand separation.
c. It synthesizes the RNA primers used to initiate DNA replication.
d. It joins the Okazaki fragments together.
Which of the following statements about DNA replication is NOT correct?
a. Leading strand synthesis is continuous, while lagging strand synthesis is
discontinuous.
b. Both leading and lagging strands are synthesized in the 5’ to 3’ direction.
c. Leading strand synthesis is conservative, while lagging strand synthesis is semi-
conservative.
d. Completion of the lagging strand requires ligation of Okazaki fragments.
How are telomeres made?
a. By ligation of adjacent Okazaki fragments.
b. Telomerase synthesizes them by copying the telomerase RNA.
c. By telomerase which is capable of synthesizing DNA in the 3’ to 5’ direction.
d. By fusion of adjacent replicons.
Eukaryotic chromosomes have telomeres that protect the terminal nucleotides from
degradation by nucleases. Bacterial chromosomes do not need telomeres because
a. bacterial DNA replication has no lagging strand synthesis, so there is no
overhang to protect.
b. bacterial chromosomes are circular.
c. bacteria have specialized proteins that protect the ends of their chromosomes.
d. bacterial DNA polymerases can synthesize DNA bidirectionally.
e. bacterial chromosomes have a single origin of replication at one end of each
linear chromosome.
What are the repeating DNA sequences at the ends of chromosomes that protect them from
loss of important DNA during replication?
a. Telomeres
b. Telomerase
c. Replicons
d. Primers
e. Promoters
Which of the following statements about nucleosomes are correct?
a. Contain about 150 bp of DNA wrapped around histones
b. The histones are called H1, H2A, H3 and H4
c. The histones are basic proteins which is important to bind DNA
d. Nucleosomes represent the first level of compaction of the eukaryotic
chromosome
e. All of the above
During translation, what is the direction of polypeptide synthesis?
a. From 5’ to 3’
b. From 3’ to 5’
c. From N-terminal to C-terminal
d. From C-terminal to N-terminal
e. From positive to negative
During DNA replication, what is the direction of DNA synthesis?
a. From 5’ to 3’
b. From 3’ to 5’
c. From N-terminal to C-terminal
d. From C-terminal to N-terminal
e. From positive to negative
The following statements are consistent with the central dogma –
a. A. During transcription, DNA is copied into RNA.
b. B. During translation, RNA sequences code for polypeptide sequences.
c. C. The process of transcription produces a polypeptide sequence.
d. D. DNA is translated into ribonucleotides.
e. A and B.
f. C and D.
Which of the following best summarizes the central dogma?
a. DNA is translated into RNA, and RNA is transcribed into polypeptides.
b. RNA is translated into DNA, and DNA is transcribed into polypeptides.
c. DNA is transcribed into RNA, and RNA is translated into polypeptides.
d. polypeptides translate DNA into ribosomes
e. All of the above.
Using the single-letter amino acid codon table shown below, translate the following mRNA:
5’-AUG,GCG,AGA,GUU,GAG,CUG,UGA-3’
a. MAGICAL
b. MARVEL
c. MONSTER
d. MAYHEM
The diagram shows a step in the experiment by Avery, MacCleod and McCarty in which
they demonstrated that DNA was the genetic material. Recall that they made an extract
from the S strain bacteria and mixed the extract with the R strain.
Why did the experimenters treat sample C with DNase?
a. To activate the DNA.
b. To allow the DNA to enter the R strain bacteria.
c. To demonstrate that DNA in the extract was the genetic material.
d. To purify the DNA from other materials in the extract.
e. All of the above.
The diagram shows a step in the experiment by Avery, MacCleod and McCarty in which
they demonstrated that DNA was the genetic material. Recall that they made an extract
from the S strain bacteria and mixed the extract with the R strain.
Why did the experimenters treat sample D with RNase?
a. To activate the DNA.
b. To demonstrate that DNA makes RNA.
c. To demonstrate that RNA is not the genetic material.
d. To purify the DNA from other materials in the extract.
e. All of the above.
The diagram shows a step in the experiment by Avery, MacCleod and McCarty in which
they demonstrated that DNA was the genetic material. Recall that they made an extract
from the S strain bacteria and mixed the extract with the R strain.
Why did the experimenters treat sample E with Protease?
a. To activate the DNA
b. To allow the DNA to enter the R strain bacteria.
c. To purify the DNA from other materials in the extract.
d. To demonstrate that protein is not the genetic material.
e. All of the above
In the structure of DNA …. (finish the sentence)
a. the “backbone” of each strand consists of deoxyribose sugars and
phosphates linked together by phosphodiester bonds.
b. the two strands of the helix are bonded together by hydrogen bonds
between purine and pyrimidine bases.
c. the two strands run antiparallel to each other meaning that one
strand runs 5’ to 3’ and the other from 3’ to 5’.
d. All of the above.
In the structure of DNA …. (finish the sentence)
a. the “backbone” of each strand consists of deoxyribose sugars and
phosphates linked together by phosphodiester bonds.
b. the two strands of the helix are bonded together by hydrogen bonds
from one purine to another purine and from one pyrimidine to another
pyrimidine.
c. the two strands run parallel to each other meaning the purines base
pair with pyrimidines and pyrimidines base pair with purines.
d. All of the above.
A DNA strand in double-stranded DNA is based paired with its complementary
strand. The strand complementary to a strand with the sequence 5’GCAAGTCATGCCGAAT-3’ would read as follows:
a. 5’-CGTTCAGTACGGCTTA-3’
b. 5’-ATTCGGCATGACTTGC-3’
c. 5’- GCAAGTCATGCCGAAT-3’
d. 5’-ATGCAGTTACAATGCA-3’
A DNA strand in double-stranded DNA is based paired with its complementary
strand. The strand complementary to a strand with the sequence 5’ATGCAGTTACAATGCA-3’ would read as follows:
a. 5’-ATTGCCGTACTGAACG-3’
b. 5’-TAACGGCATGACTTGC-3’
c. 5’-ATGCAGTTACAATGCA-3’
d. 5’-TGCATTGTAACTGCAT-3’
DNA synthesis is said to semi-conservative because …….. (finish the
sentence).
a. the parental DNA strands are not always conserved, only sometimes,
during DNA replication.
b. only one parental strand is found in each sister chromatid following
DNA replication.
c. two parental strands are found in one sister chromatid and two
daughter strands are found in the other sister chromatid following DNA
replication.
d. the daughter strands have to be separated during DNA replication.
e. none of the above.
In this very simple diagram of a DNA replication fork shown above, which red strand(s) is
the lagging DNA strand?
a. A
b. B
c. A and B
d. Neither A nor B
In this very simple diagram of a DNA replication fork shown above, which red strand(s) is
the leading DNA strand?
a. A
b. B
c. A and B
d. Neither A nor B
During DNA synthesis on the lagging strand …… (finish the sentence)
a. DNA is made in pieces called Okazaki fragments.
b. DNA synthesis is initiated by RNA primers.
c. DNA primase hops back to the opening of the replication fork to make
additional RNA primers.
d. All of the above.
e. None of the above.
During DNA replication, the function of DNA polymerase is:
a. to removes tightened coils ahead of DNA replication folk.
b. to separate double stranded DNA into single strands.
c. to synthesize DNA in both leading and lagging strands.
d. to synthesize short RNA primers.
e. to covalently attaches adjacent Okazaki fragments in the lagging
strand.
Nucleosomes:
a. are DNA structures with histone proteins wrapped around them.
b. are composed of DNA wrapping around core histones and linked
together by a DNA linker region to which histone H1 is bound.
c. are about 30 nanometers in diameter.
d. All of the above
e. None of the above
The first order of chromatin fold is:
a. the formation of 30 nanometer chromatin fiber.
b. the formation of radial loops from the 30 nanometer chromatin fiber
c. the formation of nucleosome
d. all of the above
e. none of the above
The second order of chromatin fold is:
a. the formation of 30 nanometer chromatin fiber.
b. the formation of radial loops from the 30 nanometer chromatin fiber.
c. the formation of nucleosome
d. all of the above
e. none of the above
The cartoon below depicts DNA replication.
The mechanism of replication is thought to be
a. Conservative
b. Dispersive
c. Semi-conservative
A repeating DNA sequence at the end of chromosomes that prevents them from
losing base pair sequences at their ends and from fusing together is—
a. A telomere
b. A telomerase
c. A replicon
d. A primer
e. A promoter
In eukaryotic cells histones bind to DNA to form chromatin.
basic (and smallest) organizational unit of chromatin?
a. Double helix
b. 30 nanometer fiber
c. nucleosome
d. ribosome
e. circular DNA
What is the
Gene expression
Which of the following is the correct RNA transcript of the DNA template
strand?
a. T G A C G G G T A C T C G C T G G G G A A G C C C G A G C C C C T T
A C T T A G C
b. A C T G C C C A T G A G C G A C C C C T T C G G G C T C G G G G A A
T G A A T C G
c. A C U G C C C A U G A G C G A C C C C U U C G G G C U C G G G G A A
U G A A U C G
d. U G A C G G G U
A C U C G C U G G G G A A G C C C G A G C C C C U U A C U U A G C
The following is/are true about Aminoacyl-tRNA Synthetases –
a. They catalyze the attachment of amino acids to tRNAs.
b. They are enzymes and comprise a family of proteins.
c. They utilize energy from ATP to attach amino acids to tRNAs.
d. Referred to as the second genetic code because they are able to
recognize the appropriate tRNA and the corresponding amino acid.
e. All of the above.
Which strand gets transcribed into mRNA?
a.
b.
c.
d.
The
The
The
The
coding strand. It is read 3’ to 5’ by RNA polymerase.
template strand. It is read 3’ to 5’ by RNA polymerase.
coding strand. It is read 5’ to 3’ by RNA polymerase.
template strand. It is read 5’ to 3’ by RNA polymerase.
The resulting mRNA from transcription has the following polarity –
a.
b.
c.
d.
3’to
5’to
5’to
3’to
5’
3’
5’
3’
What parts of the following structural gene are represented in processed
mRNA?
a.
b.
c.
d.
e.
The
The
The
The
The
exons only
introns only
exons and introns
promoter and exons
promoter and introns
The following statement is true about introns and exons –
a. Only exons are transcribed, introns are spliced from the RNA
b. Only introns are transcribed because exons are spliced from the DNA
c. Both introns and exons are transcribed, introns are spliced from the
mRNA.
d. The promoter, exons, and introns are transcribed. Exons are spliced
from the mRNA.
What is the promoter region?
a. It is a region of RNA that binds to the RNA polymerase and initiates
transcription.
b. It is a component of each type of RNA.
c. It is responsible for the selective nature of transcription.
d. It is a region of a parent DNA strand that binds to the RNA
polymerase and initiates transcription.
Anticodon is
a. the
b. the
c. the
acid
d. the
e. the
the term applied to—
part of the tRNA that interacts with the codon
list of amino acids that corresponds to the genetic code
concept that multiple codons sometimes code for a single amino
several three-nucleotide stretches that code for "stop"
part of the tRNA that binds to an amino acid
Which of the following may be involved in combinatorial control of eukaryotic
gene expression –
a. Activator proteins
b. Repressor proteins
c. DNA methylation
d. Alteration of chromatin structure
e. All of the above
In eukaryotic genes, exons are in the _________ regions of a gene and are
________.
a. coding, spliced out
b. noncoding, spliced out
c. coding, not spliced out
d. nocoding, not spliced out
In eukaryotic genes, introns are in the _________ regions of a gene and are
________.
a. coding, spliced out
b. noncoding, spliced out
c. coding, not spliced out
celd. nocoding, not spliced out
Mature mRNAs have 100-200 adenine nucleotides added to 3’-end. Which is true
for the poly A tails:
a. It increases stability and life span of mRNA.
b. It is encoded by gene sequence.
c. It ensures proper exit of mRNA.
d. It binds to ribosome.
The diagram above shows the three-dimensional structure of a tRNA.
What can be said about tRNAs?
a. An amino acid is linked to the 3’-end by an aminoacyl-tRNA synthetase.
b. There is a different aminoacyl-tRNA synthetase for every amino acid.
c. The GGC sequence is the anticodon recognizes and base pairs with codons in
the mRNA.
d. All of the above.
e. None of the above
Table 12.1 is a table of codons from your textbook.
Using the table above, translate the following mRNA sequence from the start codon to the
stop codon (you need to find the translation start codon first):
5’-UGCCAUGGCACCUGACUAG-3’
Choose the correct amino acid sequence.
a. Leu-Val-Arg-Cys-His-Gly
b. Cys-His-Gly-Thr
c. Pro-Trp-His-Leu_Thr
d. Met-Ala-Pro-Asp
Table 12.1 is a table of codons from your textbook.
Using the table above, translate the following mRNA sequence from the start codon to the
stop codon (you need to find the translation start codon first):
5’-CCAUGGACGAACGCUGACG-3’
Choose the correct amino acid sequence.
a. Pro-Trp-Thr-Asn-Ala-Asp
b. Met-Asp-Glu-Arg
c. Arg-Gln-Arg-Ser-Ser-Met
d. His-Gly-Arg-Thr-Leu-Thr
In bacterium growth media with both lactose and glucose, which sugar bacteria
will use first:
a. lactose
b. glucose
c. lactose and glucose at the same time
d. none of the above
In the media in which the bacteria, E. coli, is growing, the presence of
lactose ……… (finish the sentence)
a. activates the CAP activator by increasing cAMP level.
b. activates the CAP activator by decreasing cAMP level.
c. increases the binding of lac repressor to the operator of the lac
operon.
d. reduces the binding of lac repressor to the operator of the lac
operon
In the media in which the bacteria, E. coli, is growing, the absence of
glucose……… (finish the sentence)
a. activates the CAP activator by increasing cAMP level.
b. activates the CAP activator by decreasing cAMP level.
c. increases the binding of lac repressor to the operator of the lac
operon.
d. reduces the binding of lac repressor to the operator of the lac
operon
If you make a mutation in the lac repressor gene (lac I), what will happen:
a. the lac operon will not be expressed
b. the lac operon will be expressed constitutively.
c. the lac operon will be expressed only in the presence of lactose
d. All of the above
If you make a mutation in the lac Operator (Lac O), what will happen:
a. the lac operon will not be expressed
b. the lac operon will be expressed constitutively.
c. the lac operon will be expressed only in the presence of lactose
d. All of the above
The promoter regulatory elements to which activators, a class of transcription factors, bind
are called:
a.
b.
c.
d.
Mediators
Accelerators
Enhancers
Augmentors
e. None of the above
Transcription activators:
a. Binds DNA elements in enhancer to activate transcription.
b. Mediates interaction between transcription activators and GTFs.
c. producing the 5’ cap during mRNA processing.
d. splicing out non-coding introns.
Which is NOT ture about MicroRNA:
a. MicroRNA is generated from double stranded RNA by dicer.
b. MicroRNA is usually 30-50 nucleotides in length.
c. MicroRNA acts to degrade target mRNA by bringing RISC complex to the
target.
d. MicroRNAs can inhibit translation.
Let us assume that the transition of an insect from the larval stage of development to a
pupa is controlled by the expression of a microRNA. Knowing the general function of
microRNAs, what might be the possible role of the microRNA in this developmental
process?
a. Targeting the promoter of a gene required for this developmental
process.
b. Promoting the assembly of ribosomes needed for this developmental
process.
c. Enhancing the production of mRNAs required for this developmental
process.
d. Degrading a messenger RNA encoding a protein that might
interfere with this developmental process.
What the advantage for genes that are regulated at translation initiation
step?
a. For these genes, they don’t need to transcribe the genes to make
mRNAs.
b. The mRNAs of these genes form secondary structure so the mRNA is
more stable.
c. For these genes, the regulation of protein accumulation happens
faster than the
genes regulated at transcription level.
d. None of the above.
When an effector molecule binds to a transcription repressor protein, the repressor protein
changes shape and is no longer able to bind to DNA. What would happen to the rate of
transcription if the concentration of the effector molecules was reduced?
a. Increase
b. Decrease
c. Remain the same
You’ve isolated a strain of E. coli which expresses the lac operon even in the absence of
lactose. Which of the following events could explain this phenotype?
a. A. A mutation in the lacI gene which renders the lac repressor unable to bind
DNA.
b. B. A mutation in the lacI gene which prevents the lac repressor from binding
allolactose.
c. C. A mutation in the lac operator which prevents binding by lac repressor.
d. Both A and C
e. None of the above.
Complete the following: In regulation of the lac operon, the lac repressor protein .....
a. Activates lac transcription when it is bound to allolactose.
b. Represses lac transcription when it is not bound to allolactose.
c. Binds cAMP and activates transcription.
d. Binds cAMP and represses lac transcription.
Complete the following: In regulation of the lac operon, the Catabolite Activator Protein
(CAP) .....
a. Binds allolactose and activates lac transcription
b. Binds allolactose and represses lac transcription
c. Binds cAMP and activates transcription.
d. Binds cAMP and represses lac transcription.
Unlike in prokaryotes, in eukaryotes RNA transcripts are often processed in the following
ways:
a. Addition of a 5’ cap (a modified G residue).
b. Addition of a 3’ polyA tail
c. Splicing of exons
d. All of the above.
How is gene regulation by steroid hormones similar to induction of the E. coli lac operon by
lactose?
a. A. In both cases a transcription factor is imported into the nucleus.
b. B. Both cases involve binding of a small effector molecule to a transcription
factor.
c. C. Both involve binding of a transcription factor near the gene promoter.
d. B and C only.
e. All of the above.