Deck 13: Gene Expression

Question 1

Figure 13-1
Use the figure to answer the corresponding question(s).
The experimental design in Figure 13-1 was used to examine:

A) the relationship between genetic changes and metabolic enzymes.
B) the mutation rate of Neurospora.
C) resistance of Neurospora to genetic poisons.
D) toxicity of arginine metabolites.
E) growth of Neurospora in the presence of different antibiotics.

Answer 1

A

Question 2

The wobble hypothesis states that:

A) more than one ribosome can bind to an mRNA molecule.
B) some amino acids are coded for by more than one codon.
C) there is more than one stop codon in the genetic code.
D) a particular amino acid may be linked to more than one type of tRNA molecule.
E) certain tRNA anticodons can pair with more than one codon sequence.

Answer 2

E

Question 3

Which of the following serves as an "adapter" in protein synthesis and bridges the gap between mRNA and proteins?

A) tRNA
B) cDNA
C) rRNA
D) promoter sequences
E) DNA

Answer 3

A

Question 4

Figure 13-1
Use the figure to answer the corresponding question(s).
The conclusion associated with mutant strain III in Figure 13-1 was that it:

A) contained all the enzymes needed for normal metabolism.
B) was missing all the enzymes for metabolism of amino acids.
C) was missing an enzyme for metabolism and could not synthesize arginine.
D) was missing an enzyme for metabolism and could not synthesize citrulline.
E) was missing an enzyme for metabolism and could not synthesize ornithine.

Question 5

Which of the following is a characteristic of uracil?

A) The ability to bond with adenine.
B) The ability to bond with guanine.
C) It is a purine.
D) The ability to bond with cytosine.
E) It contains two nitrogenous rings.

Question 6

The codon is found in the:

A) mRNA.
B) nontemplate strand of DNA.
C) template strand of DNA.
D) tRNA.
E) rRNA.

Question 7

Why was it important in the studies of Beadle and Tatum that Neurospora is haploid?

A) Because it is easier to grow haploid molds in the laboratory.
B) Because haploid molds have simpler nutritional requirements than do diploid molds.
C) Because a mutation that arises is not masked by a normal allele on a homologous chromosome.
D) Because haploid Neurospora will always mutate.
E) Because diploid Neurospora will always mutate.

Question 8

RNA synthesis is also known as:

A) elongation.
B) reverse transcription.
C) termination.
D) translation.
E) transcription.

Question 9

Garrod first proposed that:

A) metabolic defects were due to the lack of an enzyme.
B) metabolic defects were due to excess enzyme production.
C) metabolic defects were due to chromosomal changes.
D) mutations were inheritable.
E) metabolic defects did not occur in humans.

Question 10

Figure 13-1
Use the figure to answer the corresponding question(s).
RNA differs from DNA in all of the following except:

A) RNA is usually single-standed.
B) RNA lacks thymine.
C) RNA contains uracil.
D) RNA contains ribose.
E) RNA contains cytosine.

Question 11

During protein synthesis, ribosomes:

A) attach to the mRNA molecule and travel along its length.
B) attach to the DNA molecule and travel along its length to produce an mRNA molecule.
C) translate mRNA into tRNA.
D) transcribe mRNA to tRNA.
E) translate mRNA into DNA.

Question 12

Beadle and Tatum irradiated Neurospora and initially grew the mutant strains on complete medium.How were they able to determine what type of mutation each strain had?

A) By growing the mold on a complete medium with extra vitamins and nutrients.
B) By growing the mold on minimal media supplemented with different combinations of amino acids, vitamins, etc.
C) By growing the mold in its diploid form to see which traits were masked.
D) By comparing Neurospora to other species of mold.
E) By observing the marked differences in morphology between the different strains.

Question 13

What conclusions did Beadle and Tatum reach with their studies of Neurospora?

A) Each mutant gene affected three enzymes.
B) Each mutant gene affected a pair of enzymes.
C) Each mutant gene affected only one enzyme.
D) Mutant genes had no effect on the enzymes produced by the cells.
E) Each mutant gene affected as many enzymes as were present in a particular metabolic pathway.

Question 14

Ribose differs from deoxyribose by having:

A) two attached bases.
B) one less oxygen.
C) an extra hydroxyl group.
D) an extra carbon in the ring.
E) one less carbon in the ring.

Question 15

Linus Pauling demonstrated that:

A) the structure of hemoglobin was altered by a mutation of a single gene.
B) mutations only caused defects in enzymes.
C) mutations alter the structure of RNA, but not proteins.
D) mutations were inherited.
E) the structure of hemoglobin was altered by mutations in any of a dozen genes.

Question 16

Which of the following is not a reason why Neurospora is an ideal organism to study the effects of genetic mutations?

A) Neurospora is easy to grow.
B) Neurospora grows as a haploid organism.
C) Neurospora manufactures all its necessary molecules when grown on a minimal medium.
D) A mutant Neurospora strain that cannot make a particular amino acid can still grow if that amino acid is added to the growth medium.
E) Neurospora contains homologous chromosomes that are easily viewed with a light microscope.

Question 17

Beadle and Tatum began their studies with wild-type Neurospora, which is:

A) Neurospora that only grows in the wild.
B) a mutant strain that will only grow in the lab on complete medium.
C) a strain that will not grow in the lab.
D) a virulent strain of Neurospora.
E) a normal phenotype that will grow on minimal medium.

Question 18

Uracil forms a complementary pair with __________ in RNA and __________ in DNA.

A) adenine; adenine
B) adenine; thymine
C) thymine; thymine
D) uracil; adenine
E) adenine; uracil

Question 19

Which of the following is made from DNA?

A) tRNA only
B) mRNA only
C) rRNA only
D) mRNA and tRNA only
E) mRNA, tRNA, and rRNA

Question 20

A sequence of bases located upstream from a reference point occurs:

A) towards the 3'end of the amino acid sequence.
B) towards the 5' end of the mRNA sequence.
C) towards the 3' end of the mRNA sequence.
D) towards the 5' end of the transcribed DNA strand.
E) towards the carboxyl end of the amino acid sequence.

Question 21

Binding of the appropriate aminoacyl-tRNA to the A site requires:

A) no additional energy.
B) the input of two ATP molecules to supply the needed energy.
C) energy supplied by GTP.
D) activation of the A site.
E) phosphorylation of the tRNA molecule.

Question 22

In essentially all organisms, the AUG codon codes for:

A) the initiation of translation.
B) the termination of transcription.
C) the termination of chain elongation.
D) the amino acid valine.
E) a termination tRNA molecule.

Question 23

Translocation is the process whereby the __________ moves in order to place the tRNA bound to the growing polypeptide chain in the __________ site, thereby freeing the __________ site for a new aminoacyl-tRNA.

A) mRNA; A; P
B) ribosome; P; A
C) tRNA; P; A
D) ribosome; A; P
E) tRNA; A; P

Question 24

Where is the amino-acid binding site located on the tRNA molecule?

A) in the middle of the loop
B) at the end of the 3' end of the molecule
C) in the first loop
D) along the longest stretch of base pairing in the molecule
E) on the 5 ' end of the molecule

Question 25

If a human gene mRNA were placed into a cell of yeast, it would be:

A) degraded immediately.
B) translated into a repeating amino acid chain.
C) translated into a chain of random amino acids not resembling the protein in humans.
D) translated into the protein that is found in humans.
E) integrated into the genome of the yeast.

Question 26

Figure 13-3
Use the figure to answer the corresponding question(s).
Refer to Figure 13-3.The transcription process most likely began at the area labeled:

A) A.
B) D.
C) E.
D) G.
E) F

Question 27

Leader sequences contain signals that:

A) prevent enzymes from degrading the newly synthesized mRNA.
B) inhibit ribosome binding until the appropriate time.
C) initiate chain termination.
D) allow the ribosomes to be properly positioned to translate the message.
E) allow tRNA molecules to successfully bind to mRNA.

Question 28

Figure 13-3
Use the figure to answer the corresponding question(s).
Refer to Figure 13-3.The component labeled B is:

A) DNase.
B) DNA polymerase.
C) RNA primase.
D) RNA polymerase.
E) reverse transcriptase.

Question 29

Figure 13-3
Use the figure to answer the corresponding question(s).
The process illustrated in Figure 13-3 is:

A) DNA synthesis.
B) translation.
C) transcription.
D) a frame shift mutation.
E) protein synthesis.

Question 30

Figure 13-3
Use the figure to answer the corresponding question(s).
The transcript in Figure 13-3 is labeled:

A) A.
B) B.
C) C.
D) D.
E) E.

Question 31

How does the first nucleotide at the 5' end of a new mRNA chain differ from the other nucleotides in the chain?

A) The first nucleotide is always a uracil.
B) The first nucleotide is always a cytosine.
C) The first nucleotide retains its triphosphate group, while the others do not.
D) The first nucleotide does not retain its triphosphate group, while the others in the chain do.
E) The first nucleotide is always a modified cytosine.

Question 32

Initiation of transcription requires:

A) a promoter sequence.
B) DNA polymerase.
C) an RNA primer.
D) a DNA primer.
E) Okazaki fragments.

Question 33

The enzyme peptidyl transferase, which catalyzes the transfer of the polypeptide chain attached to the tRNA in the __________ site to the aminoacyl-tRNA in the __________ site, is thought to be a(n) __________ molecule and not a protein.

A) A; P; rDNA
B) P; A; tRNA
C) A; P; mRNA
D) P; A; rRNA
E) P; A; sugar

Question 34

Aminoacyl-tRNA synthetases __________ link __________ to their respective tRNA molecules.

A) ionically; mRNAs
B) loosely; mRNAs
C) terminally; codons
D) covalently; amino acids
E) enzymatically; codons

Question 35

Figure 13-3
Use the figure to answer the corresponding question(s).

-Which of the following numbered terms represents the correct order of sequences in a prokaryotic mRNA molecule as it was synthesized? 1)
3' trailing sequences
2)
Coding sequences
3)
Leader sequences
4)
Termination signals

A) 1 $\rightarrow$ 2 $\rightarrow$ 3 $\rightarrow$ 4
B) 3 $\rightarrow$ 2 $\rightarrow$ 4 $\rightarrow$ 1
C) 2 $\rightarrow$ 1 $\rightarrow$ 4 $\rightarrow$ 3
D) 4 $\rightarrow$ 2 $\rightarrow$ 1 $\rightarrow$ 3
E) 3 $\rightarrow$ 4 $\rightarrow$ 2 $\rightarrow$ 1

Question 36

All of the following characteristics of tRNA molecules are true except::

A) They are recognized by ribosomes.
B) They have an anticodon.
C) They have an attachment site for an amino acid.
D) They are recognized by a specific aminoacyl-tRNA synthetase.
E) They are considerably larger than rRNA molecules.

Question 37

Following peptide bond formation between the amino acid in the A site on the ribosome and the growing polypeptide chain, the tRNA in the A site:

A) releases the growing polypeptide chain.
B) picks up another amino acid to add to the chain.
C) moves to the P site of the ribosome.
D) forms a peptide bond with A site of the ribosome.
E) forms a covalent bond with the P site of the ribosome.

Question 38

Which of the following numbered events represents the correct sequence of events of prokaryotic translation initiation? 1)
Large ribosomal subunit binds to initiation complex
2)
Initiation tRNA binds small ribosomal subunit
3)
Initiation complex binds to ribosome recognition sequence on mRNA

A) 1 $\rightarrow$ 2 $\rightarrow$ 3
B) 1 $\rightarrow$ 3 $\rightarrow$ 2
C) 2 $\rightarrow$ 1 $\rightarrow$ 3
D) 2 $\rightarrow$ 3 $\rightarrow$ 1
E) 3 $\rightarrow$ 2 $\rightarrow$ 1

Question 39

Why is only one strand of DNA transcribed into mRNA?

A) Because mRNA is only required in small quantities.
B) Because transcribing both DNA strands would produce different amino acid sequences.
C) Because the other strand would produce the same amino acid sequence in reverse order.
D) Because all genes are located on the same DNA strand, while the other strand acts as protection.
E) Because the other strand is transcribed directly into amino acids.

Question 40

Proteins synthesized in bacteria have which of the following at their amino terminal end?

A) N-formyl-methionine
B) N-acetyl-adenine
C) adenine triphosphate
D) the AUG codon
E) the UUU codon

Question 41

A gene can now be defined as:

A) a DNA sequence that carries information to produce a specific RNA or protein product.
B) a DNA nucleotide sequence that carries information to produce a specific polypeptide.
C) a DNA or RNA sequence that carries information to produce a single polypeptide.
D) a DNA nucleotide sequence that carries information to produce an enzyme.
E) a DNA or RNA sequence that carries information to produce a specific polypeptide.

Question 42

Walter Gilbert proposed that exons are:

A) remnants of older life forms.
B) sequences that code for protein domains that are shuffled to form new proteins.
C) the result of mutation of introns.
D) not present in prokaryotes.
E) sequences that interrupt the coding sequences of proteins.

Question 43

The process in which RNA is synthesized using a DNA template is called translation.
__________________

Question 44

The translocation process requires:

A) no additional energy.
B) activation of the P site.
C) the input of two ATP molecules to supply the needed energy.
D) energy supplied by GTP.
E) phosphorylation of the mRNA molecule.

Question 45

The nucleotide sequence in RNA to which RNA polymerase binds is called the promoter.
__________________

Question 46

A mutation that replaces one amino acid in a protein with another is called a __________ mutation.

A) frameshift
B) recombinant
C) nonsense
D) missense
E) neutral

Question 47

Compare and contrast DNA and RNA.Include the similarities and differences of their chemical structures, as well as their roles within the cell, in your comparison.

Question 48

Use a flow diagram to illustrate the flow of genetic information from DNA to protein.Include appropriate structures, chemical and cellular, as well as processes in your diagram.

Question 49

Explain the process of translation of the genetic code.Include the relevant chemical and cellular structures in your explanation.

Question 50

List the main steps involved in converting pre-mRNA to mRNA.

Question 51

Frameshift mutations result from:

A) the substitution of one base pair for another.
B) the substitution of more than one base pair.
C) the insertion or deletion of one or two base pairs.
D) the substitution of a stop codon for an amino acid-specifying codon.
E) the substitution of a start codon for an amino acid codon.

Question 52

Interrupted coding sequences include long sequences of bases that do not code for amino acids.These noncoding sequences, called __________, are found in __________ cells.

A) exons; only prokaryotic
B) introns; only prokaryotic
C) exons; only eukaryotic
D) introns; only eukaryotic
E) exons; both prokaryotic and eukaryotic

Question 53

Introns in pre-mRNA are known to:

A) code for specific protein domains.
B) undergo excision, whereby they are spliced out of the message.
C) be able to move within the mRNA, thereby giving rise to new exon combinations.
D) protect pre mRNA from enzyme degradation.
E) code for important amino acid sequences.

Question 54

Retroviruses or RNA tumor viruses use __________ to make DNA.

A) DNA polymerase
B) DNA-dependent RNA polymerase
C) RNA polymerase
D) primase
E) reverse transcriptase

Question 55

A "5' cap":

A) prevents translation.
B) prevents the binding of ribosomes.
C) marks the mRNA for degradation.
D) is added to mRNA but not pre-mRNA.
E) protects mRNA from degradation.

Question 56

The 3' end of eukaryotic pre-mRNAs are changed by:

A) removing the last phosphate group.
B) adding a "cap."
C) copying the last few bases so that it can form a duplex structure.
D) adding 100-250 adenine nucleotides.
E) phosphorylation of the mRNA molecule.

Question 57

Three nucleotides code for one amino acid.
__________________

Question 58

The template DNA strand is described as being parallel to the complementary RNA strand.
__________________

Question 59

Substitution of one base pair for another can result in a __________ mutation that results in the conversion of an amino acid specifying codon to a termination codon.

A) nonsense
B) frameshift
C) chromosomal
D) missense
E) silent

Question 60

A polyribosome is:

A) a complex of many ribosomes and an mRNA.
B) a complex of many ribosomes in eukaryotes.
C) an initiation complex in eukaryotes.
D) an elongation complex in eukaryotes.
E) a complex of a ribosome with its two subunits and several mRNAs.

Question 61

Reverse transcriptase catalyzes the synthesis of DNA from an RNA template.
__________________

Question 62

A nonsense mutation is a base-pair substitution that results in the replacement of one amino acid with another.
__________________

Question 63

The 3' trailing sequences are located before the stop codon.
__________________

Question 64

The function of snRNPs is to splice together introns.
__________________

Question 65

Molecular chaperones assist in the folding of newly synthesized mRNAs.
__________________

Question 66

What evolutionary role is served by the redundancy of the genetic code?

Question 67

The enzyme peptidyl transferase catalyzes peptide bond formation during the elongation stage of translation.
__________________

Question 68

Transcription and translation occur simultaneously in prokaryotes.Why can't this process take place in eukaryotes? What disadvantage results from such linking in prokaryotes?

Question 69

In the process of transcription, incoming RNA nucleotides are in the form of their triphosphates.
__________________

Question 70

Eukaryotic mRNA has a significantly longer half life than its prokaryotic counterpart.How is this accomplished in eukaryotes? What processes tend to degrade mRNA molecules in both eukaryotes and prokaryotes, and why are these processes needed?

Question 71

A ribosome has one binding site for mRNA and two binding sites for tRNAs.
__________________

Question 72

One function of sno-RNAs is processing pre-rRNA molecules in the mitochondrion.
__________________

Question 73

A transposon is a DNA sequence that "jumps" into the middle of a gene.
__________________

Question 74

Signal-recognition particle RNA is involved in directing the ribosome-mRNA-polypeptide complex to the rough ER.
__________________

Question 75

The poly-A tail is thought to faciliate the export of mRNA from the nucleus.
__________________

Question 76

In eukaryotes, the initiator tRNA carries the amino acid leucine.
__________________