Gene Expression/Regulation-Week 12

Question 1

What is required for formation of the transcription initiation complex in eukaryotes?

Binding of a transcription factor to the TATA box, followed by recruitment of additional transcription factors and recruitment of RNA polymerase II
Binding of a transcription factor to the transcription bubble, followed by recruitment of additional transcription factors and recruitment of RNA polymerase III
Binding of the sigma subunit to the start site followed by recruitment of RNA polymerase II
Binding of RNA polymerase II to the TATA box, followed by recruitment of transcription factors

Answer 1

Binding of a transcription factor to the TATA box, followed by recruitment of additional transcription factors and recruitment of RNA polymerase II

Question 2

Which base in an anticodon will pair with the base adenine in a codon?

Guanine
Uracil
Cytosine
Thymine

Answer 2

Uracil

Question 3

DNA affects the traits of an organism by providing the instructions for synthesizing _________.

proteins
codons
amino acids
nucleotides

Answer 3

proteins

Question 4

Certain proteins can bind to specific DNA regulatory sequences by entering

the major groove of the DNA and reading the nucleotide base pairs.
DNA’s major groove by using DNA polymerase and reading the nucleotide base pairs.
the major groove of RNA and reading the nucleotide base pairs.
the minor groove of the DNA and reading the nucleotide base pairs.

Answer 4

the major groove of the DNA and reading the nucleotide base pairs.

Question 5

Which molecule combines with proteins to form both the large and small ribosomal subunits?

rRNA
RNA polymerase
tRNA
DNA

Answer 5

rRNA

Question 6

Messenger RNA molecules contain information that is used to synthesize _________.

fatty acids
amino acids
polypeptides
nucleotides

Answer 6

polypeptides

Question 7

The gene encoding apolipoprotein B exists in two isoforms, APOB100 and APOB48. These two forms are produced as a result of

tissue-specific expression.
a gene mutation that results in a stop codon.
alternative splicing.
RNA editing.

Answer 7

RNA editing

Question 8

The enzyme beta-galactosidase acts on lactose to form galactose. In turn, the presence of galactose leads to expression of the enzymes responsible for the metabolism of galactose. In this case, lactose is serving as a carbon source and as a(n)

repressor.
operon.
DNA-binding protein.
inducer.

Answer 8

inducer

Question 9

If the sequence of bases in the template strand of a DNA molecule is 3’ ATCGCTCC 5’, what is the sequence of bases in the RNA that is transcribed from this molecule?

5’ TAGCGAGG 3’
3’ TAGCGAGG 5’
5’ UAGCGAGG 3’
3’ UAGCGAGG 5’

Answer 9

5’ UAGCGAGG 3’

Question 10

In eukaryotes, specific transcription factors have two distinct domains:

a DNA-binding domain and a RNA-binding domain.
a DNA-binding domain and an enhancer domain.
a DNA-binding domain and an operator domain.
a DNA-binding domain and an activation domain.

Question 11

Initiation of transcription differs from initiation of DNA replication in several ways. One difference is that initiation of transcription does not require

a promoter.
enzymes.
a primer.
a DNA template strand.

Answer 11

a primer

Question 12

If you were able to look very closely at a portion of DNA and find methylated histones, you would

be looking at a region of inactive chromatin.
be looking at a chromatin remodeling complex.
be mistaken since only DNA can be methylated, not histones.
be looking at a region of active chromatin.

Answer 12

be looking at a region of inactive chromatin.

Question 13

In eukaryotes, each type of RNA polymerase recognizes a different

transcription factor.
promoter.
start codon.
stop codon.

Answer 13

promoter

Question 14

If you were given a bacterial strain with a mutation in the promoter region of the trp operon the most likely effect would be

lack of expression of just the first gene in the operon.
enabling the trp operon to be expressed in the absence of tryptophan.
depression of the trp operon.
interference with RNA polymerase binding.

Answer 14

interference with RNA polymerase binding.

Question 15

Regulatory proteins can identify specific sequences on the DNA double helix without unwinding the helix. This is accomplished by inserting

DNA polymerase into the major groove of the double helix where the edges of the nitrogen bases protrude.
DNA-binding motifs into the minor groove of the double helix where the edges of the nitrogen bases protrude.
DNA-binding motifs into the major groove of the double helix where the edges of the nitrogen bases protrude.
RNA polymerase into the major groove of the double helix where the edges of the nitrogen bases protrude.

Answer 15

RNA polymerase into the major groove of the double helix where the edges of the nitrogen bases protrude.

Question 16

The connection that exists between genes and hereditary traits is based on using the information encoded in genes to synthesize

nucleotides.
codons.
complementary bases.
proteins.

Answer 16

proteins

Question 17

Codons that serve as “stop” signals for translation are recognized by

translation terminators.
aminoacyl-tRNA synthetases
tRNA.
release factors.

Answer 17

release factors

Question 18

A scientist makes three artificial mRNA strands:

(x) 5’ AAAUUUAAAUUUAAAUUUAAAUUUAAA 3’

(y) 5’ UUUCCCUUUCCCUUUCCCUUUCCCUUU 3’

(z) 5’ AUAUAUAUAUAUAUAUAUAUAUAUAU 3’

When she analyzes the polypeptides produced, she finds that:
x produces a polypeptide that is 50% phenylalanine and 50%lysine.
y produces a polypeptide that is 50% phenylalanine and 50% proline.
z produces a polypeptide that is 50% isoleucine and 50% tyrosine.

Based on these results only, the best conclusion to make is that

AUA codes for isoleucine
AAA codes for lysine and AUA codes for isoleucine
AAA codes for lysine
AAA codes for phenylalanine

Answer 18

AAA codes for lysine

Question 19

Vertebrate cells possess a protein that binds to clusters of 5-methylcytosine and ensures the gene will stay in the “off” position. This control of gene regulation is a result of

methylation.
promoter expression.
enhancer expression.
operator suppression.

Answer 19

methylation.

Question 20

The polypeptide-making organelles, which consist of protein combined with RNA, are called

centrosomes.
centrosomes.
ribosomes.
Golgi bodies.

Answer 20

ribosomes

Question 21

If a strain of bacteria had a mutation that blocked expression of the lac repressor, what would you expect as a result?

The mutant strain would grow at the same rate as wildtype if lactose was not present.
The mutant strain would outcompete wildtype strains, since it could always utilize lactose.
The mutant strain would act the same, because it would still require lac activator protein to turn on.
The mutant strain would waste energy producing enzymes in the absence of lactose.

Answer 21

The mutant strain would waste energy producing enzymes in the absence of lactose.

Question 22

To remove noncoding sequences in the pre-mRNA of eukaryotes, multiple snRNPs combine with proteins to form a larger complex called the _________.

ribosome
3’ poly-A tail
spliceosome
5’ cap

Answer 22

spliceosome

Question 23

The mutation responsible for Huntington’s disease is a

missense mutation.
triplet repeat expansion mutation.
frameshift mutation.
nonsense mutation.

Answer 23

triplet repeat expansion mutation.

Question 24

A codon is composed of how many bases?

2
1
3
4

Answer 24

3

Question 25

In prokaryotes, the form of RNA polymerase that can accurately initiate synthesis of RNA is called

RNA polymerase II.
the core polymerase.
the holoenzyme.
the sigma subunit.

Answer 25

the holoenzyme.

Question 26

The A, P, and E sites are progressively occupied by amino acids being assembled into a polypeptide. These sites are part of

tRNA.
the large ribosomal subunit.
DNA.
mRNA.

Answer 26

mRNA

Question 27

During protein synthesis in eukaryotes, which molecule passes from the nucleus to the cytoplasm and specifies the sequence of amino acids in the new polypeptide?

tRNA
rRNA
DNA
mRNA

Answer 27

mRNA

Question 28

When E. coli cells produce the amino acid tryptophan, a cluster of five genes is transcribed together. This cluster of genes is referred to as the

trp suppressor.
trp regulator.
trp operon.
trp promoter.

Answer 28

trp operon

Question 29

The hallmark of multicellular organisms is their ability to

adjust quickly to outside environment.
maintain homeostasis.
grow and divide rapidly.
respond by gene action to oxygen availability.

Answer 29

maintain homeostasis.

Question 30

A protein that regulates transcription by binding to the operator is known as the

operon.
repressor.
promoter.
operator.

Answer 30

repressor

Question 31

Gene _________refers to the combined processes of transcription and translation.

replication
regulation
expression
modification

Answer 31

expression

Question 32

During protein synthesis in eukaryotes, what happens during RNA splicing?

The product of translation, called the primary transcript, is cut and some pieces are joined back together to form the mature mRNA.
The product of transcription, called the primary transcript, is cut and some pieces are joined back together to form the mature tRNA.
The product of transcription, called the primary transcript, is cut and all pieces are joined back together to form the mature mRNA.
The product of transcription, called the primary transcript, is cut and some pieces are joined back together to form the mature mRNA.

Question 33

The template strand of a DNA segment that codes for mRNA has the sequence: ATGCGT. Which tRNA anticodons would pair with the mRNA that is coded for by this sequence?

UAC GCA.
AUG CGU.
ATG CGT.
UAG CGU.

Answer 33

AUG CGU.

Question 34

You are studying regulation of a prokaryotic operon. Experiments show that expression of the operon is increased when levels of biosynthetic product from that pathway are low. Based on this information, what is a likely mode of regulation?

The product binds to the biosynthetic enzymes, blocking them directly.
The product binds an activator, helping RNA polymerase to bind the promoter.
The product binds a repressor, preventing it from binding the operator.
The product binds a repressor, allowing it to bind the operator.

Answer 34

The product binds a repressor, allowing it to bind the operator.