Midterm 2 Flashcards
1
Q
Which of the following statements about prokaryotic mRNA molecules is false?
(a) A single prokaryotic mRNA molecule can be translated into several
proteins.
(b) Ribosomes must bind to the 5′ cap before initiating translation.
(c) mRNAs are not polyadenylated.
(d) Ribosomes can start translating an mRNA molecule before transcription is
complete.
A
(b) Ribosomes must bind to the 5′ cap before initiating translation.
2
Q
Figure Q7-6 shows a ribose sugar. The part of the ribose sugar where a new
ribonucleotide will attach in an RNA molecule is pointed to by arrow ____.
A
(c) 4.
3
Q
"Since introns do not contain protein-coding information, they do not have to be removed precisely (meaning, a nucleotide here and there should not matter) from the primary transcript during RNA splicing."
A
False
4
Q
The repair of mismatched base pairs or damaged nucleotides in a DNA strand requires a multistep process. Which choice below describes the known sequence of events in this process?
A
(a) DNA damage is recognized, the newly synthesized strand is identified by an existing nick in the backbone, a segment of the new strand is removed by repair proteins, the gap is filled by DNA polymerase, and the strand is sealed by DNA ligase
5
Q
There are several reasons why the primase used to make the RNA primer for
DNA replication is not suitable for gene transcription. Which of the statements
below is not one of those reasons?
A
(b) Primase can initiate RNA synthesis without the need for a base-paired
primer.
6
Q
Sickle-cell anemia is an example of an inherited disease. Individuals with this disorder have misshapen (sickle-shaped) red blood cells caused by a change in the sequence of the β-globin gene. What is the nature of the change?
A
(b) base-pair change
7
Q
RNA in cells differs from DNA in that ___________________.
A
(c) it is single-stranded and can fold up into a variety of structures
8
Q
You have discovered an “Exo-“ mutant form of DNA polymerase in which the 3′- to-5′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged. Which of the following properties do you expect the mutant polymerase to have?
A
(d) It will be more likely to generate mismatched base pairs.
9
Q
Which of the following molecules is thought to have arisen first during evolution?
A
(c) RNA
10
Q
After damaged DNA has been repaired, nicks in the phosphate backbone are maintained as a way to identify the strand that was repaired.
A
False
11
Q
The ribosome is important for catalyzing the formation of peptide bonds. Which
of the following statements is true?
(a) The number of rRNA molecules that make up a ribosome greatly exceeds
the number of protein molecules found in the ribosome.
(b) The large subunit of the ribosome is important for binding to the mRNA.
(c) The catalytic site for peptide bond formation is formed primarily from an
rRNA.
(d) Once the large and small subunits of the ribosome assemble, they will not
separate from each other until degraded by the proteasome.
A
(c) The catalytic site for peptide bond formation is formed primarily from an
rRNA.
12
Q
DNA ligase is required to seal the sugar-phosphate backbone between all the DNA fragments on the lagging strand.
A
True
13
Q
Primase is needed to initiate DNA replication on both the leading strand and the lagging strand.
A
True
14
Q
What part of the DNA replication process would be most directly affected if a strain of bacteria lacking DNA ligase were used to make the cell extracts?
A
(d) lagging-strand completion
15
Q
DNA replication origins are typically rich in G-C base pairs.
A
False
16
Q
What part of the DNA replication process would be most directly affected if a strain of bacteria lacking helicase were used to make the cell extracts?
A
(a) initiation of DNA synthesis
17
Q
The 3′ overhang “invades” the homologous DNA duplex, which can be used as a primer for the repair DNA polymerase.
A
True
18
Q
Which of the following statements about sequence proofreading during DNA replication is false?
A
(b) The exonuclease activity cleaves DNA in the 5′-to-3′ direction.
19
Q
Ionizing radiation and oxidative damage can cause DNA double-strand breaks.
A
True
20
Q
Match the following structures with their names. (Figure Q7-10)
- Uracil
- Deoxyribose
- Ribose
- Adenine
A
A—4; B—2; C—1; D—3
21
Q
Which of the following statements is true?
(a) Ribosomes are large RNA structures composed solely of rRNA.
(b) Ribosomes are synthesized entirely in the cytoplasm.
(c) rRNA contains the catalytic activity that joins amino acids together.
(d) A ribosome binds one tRNA at a time.
A
(c) rRNA contains the catalytic activity that joins amino acids together.
22
Q
Total nucleic acids are extracted from a culture of yeast cells and are then mixed
with resin beads to which the polynucleotide 5
-
TTTTTTTTTTTTTTTTTTTTTTTTT-3
has been covalently attached. After a
short incubation, the beads are then extracted from the mixture. When you
analyze the cellular nucleic acids that have stuck to the beads, which of the
following is most abundant?
A
(d) mRNA
23
Q
Which of the following statements is false?
(a) A new RNA molecule can begin to be synthesized from a gene before the
previous RNA molecule’s synthesis is completed.
(b) If two genes are to be expressed in a cell, these two genes can be
transcribed with different efficiencies.
(c) RNA polymerase is responsible for both unwinding the DNA helix and
catalyzing the formation of the phosphodiester bonds between nucleotides.
(d) Unlike DNA, RNA uses a uracil base and a deoxyribose sugar.
A
Choice (d) is false. RNA nucleotides contain the sugar ribose.
24
Q
The DNA duplex consists of two long covalent polymers wrapped around each other many times over their entire length. The separation of the DNA strands for replication causes the strands to be “overwound” in front of the replication fork. How does the cell relieve the torsional stress created along the DNA duplex during replication?
A
(b) Topoisomerases break the covalent bonds of the backbone allowing the local unwinding of DNA ahead of the replication fork.
25
When DNA is being replicated inside a cell, local heating occurs, allowing the two strands to separate.
False
26
Which of the following pairs of codons might you expect to be read by the same
tRNA as a result of wobble?
(c) CAC and CAU
27
```
Because all DNA polymerases synthesize DNA in the 5′-to-3′ direction, and the parental strands are antiparallel, DNA replication is accomplished with the use of two mechanisms: continuous and discontinuous replication. Indicate whether the following items relate to (1) continuous replication, (2) discontinuous replication, or (3) both modes of replication.
______ primase
______ single-strand binding protein ______ sliding clamp
______ RNA primers
______ leading strand
______ lagging strand
______ Okazaki fragments
______ DNA helicase
______ DNA ligase
```
```
Primase 3
Single Strand Binding Proteins 2
Sliding Camp 3
RNA primers 3
Leading strand 1
Lagging strand 2
Okazaki fragments 2
DNA helicase 3
DNA Ligase 2
```
28
The chromatin structure in eukaryotic cells is much more complicated than that observed in prokaryotic cells. This is thought to be the reason that DNA replication occurs much faster in prokaryotes. How much faster is it?
(c) 10×
29
The repair polymerase does not require the aid of the sliding clamp, because it is only synthesizing DNA over very short stretches.
True
30
Select the option that best completes the following statement: Nonhomologous end joining is a process by which a double-stranded DNA end is joined ___________________.
(c) to the nearest available double-stranded DNA end.
31
Which of the following does not occur before a eukaryotic mRNA is exported
from the nucleus?
(a) The ribosome binds to the mRNA.
32
In somatic cells, if a base is mismatched in one new daughter strand during DNA replication, and is not repaired, what fraction of the DNA duplexes will have a permanent change in the DNA sequence after the second round of DNA replication?
(b) 1/4
33
Beside the distortion in the DNA backbone caused by a mismatched base pair, what additional mark is there on eukaryotic DNA to indicate which strand needs to be repaired?
(c) a nick in the new strand
34
Which of the following statements correctly explains what it means for DNA replication to be bidirectional?
(d) The replication forks formed at the origin move in opposite directions.
35
Which of the following methods is not used by cells to regulate the amount of a
protein in the cell?
(d) Nuclear pore complexes can regulate the speed at which newly
synthesized proteins are exported from the nucleus into the cytoplasm.
36
snRNAs ___________________.
(d) can bind to specific sequences at intron-exon boundaries through
complementary base-pairing.
37
The events listed below are all necessary for homologous recombination to occur properly:
```
A. Holliday junction cut and ligated
B. strand invasion
C. DNA synthesis
D. DNA ligation
E. double-strand break
F. nucleases create uneven strands
```
Which of the following is the correct order of events during homologous recombination?
(d) E, F, B, C, D, A
38
The classic experiments conducted by Meselson and Stahl demonstrated that DNA replication is accomplished by employing a ________________ mechanism.
(b) semiconservative
39
A mutation in the tRNA for the amino acid lysine results in the anticodon
sequence 5′-UAU-3′ (instead of 5′-UUU-3′). Which of the following
aberrations in protein synthesis might this tRNA cause?
(b) The mutant tRNALys will be able to pair with the codon 5′-AUA-3′, which codes for
isoleucine.
40
How many replication forks are formed when an origin of replication is opened?
(b) 2
41
The first step in repair requires a nuclease to remove a stretch of base pairs from the 5′ end of each strand at the site of the break.
True
42
A poison added to an in vitro translation mixture containing mRNA molecules
with the sequence 5′-AUGAAAAAAAAAAAAUAA-3′ has the following effect:
the only product made is a Met-Lys dipeptide that remains attached to the
ribosome. What is the most likely way in which the poison acts to inhibit protein
synthesis?
(b) It inhibits movement of the small subunit relative to the large subunit.
43
epurination of DNA is a rare event that is caused by ultraviolet irradiation
False
44
Which amino acid would you expect a tRNA with the anticodon 5′-CUU-3′ to
carry?
(a) lysine
45
Which of the following statements is not an accurate statement about thymine dimers?
(b) Thymine dimers are covalent links between thymidines on opposite DNA strands.
46
The concentration of a particular protein, X, in a normal human cell rises
gradually from a low point, immediately after cell division, to a high point, just
before cell division, and then drops sharply. The level of its mRNA in the cell
remains fairly constant throughout this time. Protein X is required for cell growth
and survival, but the drop in its level just before cell division is essential for
division to proceed. You have isolated a line of human cells that grow in size in
culture but cannot divide, and on analyzing these mutants, you find that levels of
X mRNA in the mutant cells are normal. Which of the following mutations in the
gene for X could explain these results?
(c) the deletion of a sequence that encodes sites at which ubiquitin can be
attached to the protein
47
For a cell's genetic material to be used, the information is first copied from the DNA into the nucleotide sequence of RNA in a process called __________________. Various kinds of RNA are produced, each with different functions. __________________ molecules code for proteins, __________________ molecules act as adaptors for protein synthesis, __________________ molecules are integral components of the ribosome, and
__________________ molecules are important in the splicing of RNA transcripts.
transcription, mRNA, tRNA, rRNA, snRNA
48
Which of the following statements about the proteasome is false?
(c) Misfolded proteins are delivered to the proteasome, where they are
sequestered from the cytoplasm and can attempt to refold.
49
DNA polymerase catalyzes the joining of a nucleotide to a growing DNA strand. What prevents this enzyme from catalyzing the reverse reaction?
(a) hydrolysis of pyrophosphate (PPi) to inorganic phosphate (Pi) + Pi
50
You have a bacterial strain with a mutation that removes the transcription
termination signal from the Abd operon. Which of the following statements
describes the most likely effect of this mutation on Abd transcription?
(b) The Abd RNA from the mutant strain will be longer than normal.
51
What do you predict would happen if you created a tRNA with an anticodon of
5′-CAA-3′ that is charged with methionine, and added this modified tRNA to a
cell-free translation system that has all the normal components required for
translating RNAs?
(b) methionine would be incorporated into proteins at some positions where
leucine should be
52
In addition to the repair of DNA double-strand breaks, homologous recombination is a mechanism for generating genetic diversity by swapping segments of parental chromosomes. During which process does swapping occur?
(c) meiosis
53
Which of the following statements is true?
(a) The two genes must be transcribed into RNA using the same strand of
DNA.
(b) If gene A is transcribed in a cell, gene B cannot be transcribed.
(c) Gene A and gene B can be transcribed at different rates, producing
different amounts of RNA within the same cell.
(d) If gene A is transcribed in a cell, gene B must be transcribed.
(c) Gene A and gene B can be transcribed at different rates, producing
different amounts of RNA within the same cell.
54
In eukaryotic cells, general transcription factors are required for the activity of all
promoters transcribed by RNA polymerase II. The assembly of the general
transcription factors begins with the binding of the factor __________________
to DNA, causing a marked local distortion in the DNA. This factor binds at the
DNA sequence called the __________________ box, which is typically located
25 nucleotides upstream from the transcription start site. Once RNA polymerase
II has been brought to the promoter DNA, it must be released to begin making
transcripts. This release process is facilitated by the addition of phosphate groups
to the tail of RNA polymerase by the factor __________________. It must be
remembered that the general transcription factors and RNA polymerase are not
sufficient to initiate transcription in the cell and are affected by proteins bound
thousands of nucleotides away from the promoter. Proteins that link the distantly
bound transcription regulators to RNA polymerase and the general transcription
factors include the large complex of proteins called the__________________.
The packing of DNA into chromatin also affects transcriptional initiation, and
histone __________________ is an enzyme that can render the DNA less
accessible to the general transcription factors.
TFIID; TATA; TFIIH; mediator; deacetylase
55
5′-ATAGGCATTCGATCCGGATAGCAT-3′
3′-TATCCGTAAGCTAGGCCTATCGTA-5′
Which of the following RNA molecules could be transcribed from this piece of
DNA?
(b) 5′-AUAGGCAUUCGAUCCGGAUAGCAU-3′
56
Below is the sequence from the 3′ end of an mRNA.
5′-CCGUUACCAGGCCUCAUUAUUGGUAACGGAAAAAAAAAAAAAA-3′
If you were told that this sequence contains the stop codon for the protein encoded
by this mRNA, what is the anticodon on the tRNA in the P site of the ribosome
when release factor binds to the A site?
(a) 5′-CCA-3′
57
When using a repeating trinucleotide sequence (such as 5′-AAC-3′) in a cell-
free translation system, you will obtain:
(a) three different types of peptides, each made up of a single amino acid
58
Which of the following might decrease the transcription of only one specific gene
in a bacterial cell?
(d) a mutation that introduced extensive sequence changes into the DNA that
precedes the gene's transcription start site
59
The sliding clamp is loaded once on each DNA strand, where it remains associated until replication is complete.
False
60
A pregnant mouse is exposed to high levels of a chemical. Many of the mice in her litter are deformed, but when they are interbred with each other, all their offspring are normal. Which two of the following statements could explain these results?
A and D
A: in the deformed mice, somatic cells but not germ cells were mutated.
D: The toxic chemical affects development but is not mutagenic
61
Telomerase is a DNA polymerase that carries its own RNA molecule to use as a primer at the end of the lagging strand.
True
62
There is a single enzyme that degrades the RNA primers and lays down the corresponding DNA sequence behind it
False
63
Human beings with the inherited disease xeroderma pigmentosum have serious problems with lesions on their skin and often develop skin cancer with repeated exposure to sunlight. What type of DNA damage is not being recognized in the cells of these individuals?
(d) ultraviolet irradiation damage
64
Homologous recombination is an important mechanism in which organisms use a "backup" copy of the DNA as a template to fix double-strand breaks without loss of genetic information. Which of the following is not necessary for homologous recombination to occur?
(b) 5′ DNA strand overhangs
65
A molecule of bacterial DNA introduced into a yeast cell is imported into the nucleus but fails to replicate with the yeast DNA. Where do you think the block to replication arises? Choose the protein or protein complex below that is most probably responsible for the failure to replicate bacterial DNA. Give an explanation for your answer.
(d) initiator proteins
66
In eukaryotes, but not in prokaryotes, ribosomes find the start site of translation
by ____________________________.
(b) scanning along the mRNA from the 5′ end.
67
Initiator proteins bind to replication origins and disrupt hydrogen bonds between the two DNA strands being copied. Which of the factors below does not contribute to the relative ease of strand separation by initiator proteins?
(b) the reaction can occur at room temperature
68
You are examining the DNA sequences that code for the enzyme phosphofructokinase in skinks and Komodo dragons. You notice that the coding sequence that actually directs the sequence of amino acids in the enzyme is very similar in the two organisms but that the surrounding sequences vary quite a bit. What is the most likely explanation for this?
(d) Mutations in coding sequences are more likely to be deleterious to the organism than mutations in noncoding sequences.
69
If the genome of the bacterium E. coli requires about 20 minutes to replicate itself, how can the genome of the fruit fly Drosophila be replicated in only 3 minutes?
(d) Drosophila DNA contains more origins of replication than E. coli DNA.
70
Figure Q7-6 shows a ribose sugar. RNA bases are added to the part of the ribose
sugar pointed to by arrow _____.
(a) 3.
71
Telomeres serve as caps at the ends of linear chromosomes. Which of the following is not true regarding the replication of telomeric sequences?
(d) The leading strand doubles back on itself to form a primer for the lagging strand.
72
Which of the following statements about the newly synthesized strand of a human chromosome is true?
(d) It was synthesized from multiple origins by a mixture of continuous and discontinuous DNA synthesis.
73
Ribozymes catalyze which of the following reactions?
(c) RNA splicing
74
Sometimes, chemical damage to DNA can occur just before DNA replication begins, not giving the repair system enough time to correct the error before the DNA is duplicated. This gives rise to mutation. If the cytosine in the sequence TCAT is deaminated and not repaired, which of the following is the point mutation you would observe after this segment has undergone two rounds of DNA replication?
(a) TTAT
75
According to current thinking, the minimum requirement for life to have
originated on Earth was the formation of a _______________.
(d) molecule that could catalyze its own replication.
76
The piece of RNA below includes the region that codes for the binding site for the
initiator tRNA needed in translation.
5′-GUUUCCCGUAUACAUGCGUGCCGGGGGC-3′
Which amino acid will be on the tRNA that is the first to bind to the A site of the
ribosome?
(b) arginine
77
Transcription in bacteria differs from transcription in a eukaryotic cell because
__________________________.
(a) RNA polymerase (along with its sigma subunit) can initiate transcription
on its own.
78
Once an mRNA is produced, its message can be decoded on ribosomes. The
ribosome is composed of two subunits: the __________________ subunit, which
catalyzes the formation of the peptide bonds that link the amino acids together
into a polypeptide chain, and the __________________ subunit, which matches
the tRNAs to the codons of the mRNA. During the chain elongation process of
translating an mRNA into protein, the growing polypeptide chain attached to a
tRNA is bound to the __________________ site of the ribosome. An incoming
aminoacyl-tRNA carrying the next amino acid in the chain will bind to the
__________________ site by forming base pairs with the exposed codon in the
mRNA. The __________________ enzyme catalyzes the formation of a new
peptide bond between the growing polypeptide chain and the newly arriving
amino acid. The end of a protein-coding message is signaled by the presence of a
stop codon, which binds the __________________ called release factor.
Eventually, most proteins will be degraded by a large complex of proteolytic
enzymes called the __________________.
large; small; P; A; peptidyl transferase; protein; proteasome;
79
Genes in eukaryotic cells often have intronic sequences coded for within the
DNA. These sequences are ultimately not translated into proteins. Why?
(a) Intronic sequences are removed from RNA molecules by the spliceosome,
which works in the nucleus.
80
What part of the DNA replication process would be most directly affected if a strain of bacteria lacking single-strand binding protein were used to make the cell extracts?
(b) Okazaki fragment synthesis
81
Figure Q7-6 shows a ribose sugar. The part of the ribose sugar that is different
from the deoxyribose sugar used in DNA is pointed to by arrow ____.
(c) 5.
82
You have a segment of DNA that contains the following sequence:
5′-GGACTAGACAATAGGGACCTAGAGATTCCGAAA-3′
3′-CCTGATCTGTTATCCCTGGATCTCTAAGGCTTT-5′
You know that the RNA transcribed from this segment contains the following
sequence:
5′-GGACUAGACAAUAGGGACCUAGAGAUUCCGAAA-3′
Which of the following choices best describes how transcription occurs?
(d) the bottom strand is the template strand; RNA polymerase moves along
this strand from 3′ to 5′
83
Homologous recombination cannot occur in prokaryotic cells, because they are haploid, and therefore have no extra copy of the chromosome to use as a template for repair
False
84
The process of DNA replication requires that each of the parental DNA strands be used as a ___________________ to produce a duplicate of the opposing strand.
(c)Template
85
Meselson and Stahl ruled out the dispersive model for DNA replication.
True
86
What part of the DNA replication process would be most directly affected if a strain of bacteria lacking the exonuclease activity of DNA polymerase were used to make the cell extracts?
(d) lagging-strand completion
87
Sometimes, chemical damage to DNA can occur just before DNA replication begins, not giving the repair system enough time to correct the error before the DNA is duplicated. This gives rise to mutation. If the adenosine in the sequence TCAT is depurinated and not repaired, which of the following is the point mutation you would observe after this segment has undergone two rounds of DNA replication?
(c) TCT
88
Primase requires a proofreading function that ensures there are no errors in the RNA primers used for DNA replication.
False
89
The sigma subunit of bacterial RNA polymerase ___________________.
(c) recognizes promoter sites in the DNA.
90
You are studying a disease that is caused by a virus, but when you purify the virus
particles and analyze them you find they contain no trace of DNA. Which of the
following molecules are likely to contain the genetic information of the virus?
(a) high-energy phosphate groups
91
Unlike DNA, which typically forms a helical structure, different molecules of
RNA can fold into a variety of three-dimensional shapes. This is largely because
___________________.
(d) RNA is single-stranded.
92
Nonhomologous end joining can result in all but which of the following?
(a) the recovery of lost nucleotides on a damaged DNA strand
93
Which of the following statements about RNA splicing is false?
(a) Conventional introns are not found in bacterial genes.
(b) For a gene to function properly, every exon must be removed from the
primary transcript in the same fashion on every mRNA molecule produced
from the same gene.
(c) Small RNA molecules in the nucleus perform the splicing reactions
necessary for the removal of introns.
(d) Splicing occurs after the 5′ cap has been added to the end of the primary
transcript.
(b) The primary transcript of a gene can sometimes be spliced differently so that different
exons can be stitched together to produce distinct proteins in a process called alternative
splicing.
94
Which one of the following is the main reason that a typical eukaryotic gene is
able to respond to a far greater variety of regulatory signals than a typical
prokaryotic gene or operon?
(c) The transcription of a eukaryotic gene can be influenced by proteins that
bind far from the promoter.
95
D. DNA replication is a bidirectional process that is initiated at multiple
locations along chromosomes in eukaryotic cells.
True
96
How does the total number of replication origins in bacterial cells compare with the number of origins in human cells?
(d) 1 versus 10,000
97
DNA replication is considered semiconservative because
(c) each daughter DNA molecule consists of one strand from the parent DNA
molecule and one new strand.
98
What part of the DNA replication process would be most directly affected if a strain of bacteria lacking primase were used to make the cell extracts?
(a) initiation of DNA synthesis
99
Which of the following molecules of RNA would you predict to be the most
likely to fold into a specific structure as a result of intramolecular base-pairing?
(a) 5′-CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3′
100
DNA polymerases are processive, which means that they remain tightly associated with the template strand while moving rapidly and adding nucleotides to the growing daughter strand. Which piece of the replication machinery accounts for this characteristic?
(b) sliding clamp
101
Even though DNA polymerase has a proofreading function, it still introduces errors in the newly synthesized strand at a rate of 1 per 107 nucleotides. To what degree does the mismatch repair system decrease the error rate arising from DNA replication?
(d) 100-fold
102
Transcription is similar to DNA replication in that ___________________.
(d) nucleotide polymerization occurs only in the 5'-to-3' direction
103
Several members of the same family were diagnosed with the same kind of cancer when they were unusually young. Which one of the following is the most likely explanation for this phenomenon? It is possible that the individuals with the cancer have _______________________.
(c) inherited a mutation in a gene required for mismatch repair.
104
The DNA template used to repair the broken strand is the homologous chromosome inherited from the other parent.
False
105
The repair polymerase is the enzyme that proofreads the newly synthesized strands to ensure the accuracy of DNA replication.
False
106
Nonhomologous end joining is a mechanism that ensures that DNA double-strand breaks are repaired with a high degree of fidelity to the original DNA sequence.
False
107
The instructions specified by the DNA will ultimately specify the sequence of
proteins. This process involves DNA, made up of ____ different nucleotides,
which gets _________________ into RNA, which is then _________________
into proteins, made up of _____ different amino acids. In eukaryotic cells, DNA
gets made into RNA in the _________________, while proteins are produced
from RNA in the _________________. The segment of DNA called a
_________________ is the portion that is copied into RNA; this process is
catalyzed by RNA _________________.
The instructions specified by the DNA will ultimately specify the sequence of proteins.
This process involves DNA, made up of 4 different nucleotides, which gets transcribed
into RNA, which is then translated into proteins, made up of 20 different amino acids. In
eukaryotic cells, DNA gets made into RNA in the nucleus, while proteins are produced
from RNA in the cytoplasm. The segment of DNA called a gene is the portion that is
copied into RNA; this process is catalyzed by RNA polymerase.
108
Which of the following statements about the genetic code is correct?
(b) The genetic code is redundant.
