|
| 2 |
Go |
Q:
|
Which of the following is true about codons? |
|
A
|
Only one codon codes for each amino acid. |
B
|
Several codons are specific to one amino acid. |
C
|
Several amino acids are sepcific to one codon. |
D
|
Four codons do not code for amino acids. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 4 |
Go |
Q:
|
A DNA mutation results in the early truncation of a polypeptide. Which of the following describes this type of mutation? |
|
A
|
missense mutation |
B
|
nonsense mutation |
C
|
silent mutation |
D
|
neutral mutation |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 5 |
Go |
Q:
|
A biologist has isolated the mRNA used for the translation of a particular protein. He wants to transform the gene for the protein into another organism, for which he needs DNA strands. Which of the following enzymes is most adequately suited to this task? |
|
A
|
reverse transcriptase |
B
|
DNA polymerase |
C
|
topoisomerase |
D
|
transcriptomerase |
|
|
|
Tags:
DNA Replication and Repair | Genetic Code, Transcription, Translation | |
|
| 6 |
Go |
Q:
|
The Lac operon contains three genes; Lac A, Lac Z, and Lac Y. A promoter lies upstream of the three genes. When IPTG, an inducer of the lac operon, indirectly exposes the promoter, which of the operon genes will be transcribed? |
|
A
|
none; only genes immediately adjacent to the promoter will be transcribed |
B
|
the first gene in the operon; all genes are controlled by their own individual promoters |
C
|
none; promoters do not control the transcription of genes on operons, only standalone genes |
D
|
all; all genes within a single operon are transcribed as a unit, as initiated by a single promoter |
|
|
|
Tags:
Genetic Code, Transcription, Translation | Prokaryotes | |
|
| 8 |
Go |
Q:
|
Telomerase is responsible for ______ the size of telomeres, and its function is often _____ in carcinogenesis. |
|
A
|
maintaining ... decreased |
B
|
maintaining ... increased |
C
|
decreasing ... decreased |
D
|
decreasing ... increased |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 9 |
Go |
Q:
|
micro RNAs (miRNAs) are short sequences of RNA which bind target nucleic acid sequences in order to inhibit gene expression. which of the following is the most likely mechanism of action of miRNAs in this function?
|
|
A
|
binding to complementary DNA sequences to inhibit transcription |
B
|
binding to complementary mRNA sequences to inhibit transcription |
C
|
binding to complementary DNA sequences to inhibit translation |
D
|
binding to complementary mRNA sequences to inhibit translation |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 10 |
Go |
Q:
|
Certain viruses lack 5' caps on their mRNA sequences. Which of the following answers explains one of the ways in which such viruses produce their proteins?
|
|
A
|
They carry their own ribosomes which do not need 5' caps in order to initiate translation
|
B
|
They use Internal Ribosomal Entry Sites (IRES) which allow for the assembly of cellular ribosomes to initiate translation
|
C
|
They carry out protein synthesis prior to infection; the mRNA is incorporated into the host nucleic acids in dormancy
|
D
|
They initiate translation from the 3' polyA tail instead of the 5' cap to avoid the problem.
|
|
|
|
Tags:
Genetic Code, Transcription, Translation | Viruses | |
|
| 11 |
Go |
Q:
|
The rough ER (endoplasmic reticulum) has ribosomes its surface. These ribosomes are noted for performing which of the following functions? |
|
A
|
translating proteins out of the ER |
B
|
translating proteins into the ER |
C
|
transporting proteins out of the ER |
D
|
transporting proteins into the ER |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 12 |
Go |
Q:
|
Both Group VI and VII viruses are retroviruses. Group VI is characterized by ssRNA as the genome, while Group VII is characterized by dsDNA as the genome. As retroviruses, both Groups code for reverse transcriptase. The reverse transcriptase in both Groups used for which of the following purposes? |
|
A
|
transcription of genomic RNA from mRNA |
B
|
transcription of DNA from RNA |
C
|
transcription of mRNA from genomic RNA |
D
|
transcription of mRNA from DNA |
|
|
|
Tags:
Genetic Code, Transcription, Translation | Viruses | |
|
| 13 |
Go |
Q:
|
A novel enzyme was discovered in bacterial family. The enzyme was structurally dissimilar to any other protein produced by the bacteria. It had novel function as well. Which of the following types of mutations is most likey to result in such an enzyme? |
|
A
|
Frameshift mutation |
B
|
Silent mutation |
C
|
Point mutation |
D
|
Reversion mutation |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 14 |
Go |
Q:
|
A polypeptide is typically translated from mRNA with 107 amino acids. After a mutation, the polypeptide truncates early after only 31 amino acids. Which type of mutation may have caused this result?
I. Frameshift Mutation
II. Point Mutation
III. Silent Mutation |
|
A
|
I only |
B
|
II only |
C
|
I and II only |
D
|
I, II, and III |
|
|
|
Tags:
Protein Structure and Function | Genetic Code, Transcription, Translation | |
|
| 15 |
Go |
Q:
|
A biologist has isolated the mRNA used for the translation of a particular protein. He wants to transform the gene for the protein into another organism, for which he needs DNA strands. Which of the following enzymes is most adequately suited to this task? |
|
A
|
reverse transcriptase |
B
|
DNA polymerase |
C
|
topoisomerase |
D
|
transcriptomerase |
|
|
|
Tags:
Genetic Code, Transcription, Translation | Recombinant DNA and Biotechnology | Viruses | |
|
| 17 |
Go |
Q:
|
How many of the following modifications take place in post-transcription pre-mRNA transcripts within the nucleus?
1. Cleavage of mRNA into smaller transcripts
2. Splicing of exons; removal of introns
3. Glycosylation of various methionine amino acids
4. Attachment of a poly-A tail
5. Attachment of a 5'-Cap
|
|
A
|
None |
B
|
All of the above |
C
|
2 of the above |
D
|
3 of the above |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 18 |
Go |
Q:
|
A base pair substitution occurs that creates an early stop codon. What type of mutation occurred? |
|
A
|
frame shift |
B
|
nonsense mutation |
C
|
silent mutation |
D
|
none of the above |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 19 |
Go |
Q:
|
The antisense strand of a DNA segment encoding a protein is as follows:
5'-agt tag cac gca-3'. What would be the sequence of the mRNA strand encoded? |
|
A
|
5'-agt tag cac gca-3' |
B
|
5'-tgc gtg cta act-3' |
C
|
5'-agu uag cac gca-3' |
D
|
5'-ugc gug cua acu-3' |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 20 |
Go |
Q:
|
Which of the following term matches with this definition? A codon will code for one and only one amino acid. |
|
A
|
degenerative |
B
|
universal coding |
C
|
unambiguous |
D
|
selective |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 21 |
Go |
Q:
|
RNA-dependent RNA polymerase catalyzes the replication of RNA from an RNA template as opposed to the typical DNA-dependent RNA polymerase present during gene transcription. Many human RNA viruses require RNA-dependent RNA polymerases to replicate their genomes. This polymerase must be encoded by the virus itself; it cannot be sourced from the host. The reason for this is that |
|
A
|
human RNA-dependent RNA polymerase is incompatible with viral RNA |
B
|
human RNA-dependent RNA polymerase will recognize viral RNA as foreign and trigger an immune response. |
C
|
human RNA-dependent RNA polymerases will degrade rather than replicate viral RNA. |
D
|
humans lack RNA-dependent RNA polymerases. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | Viruses | |
|
| 22 |
Go |
Q:
|
A particular bacterial cell has a mutation in its genome such that it has a nonfunctional A-site in all of the ribosomes it produces. Such a mutation would result in which of the following? |
|
A
|
Increased production of protein within the cell |
B
|
Production of proteins lacking in disulfide bonds |
C
|
Complete inability to translate mRNA |
D
|
Increased speed of ribosomal denaturation in low pH environments |
|
|
|
Tags:
Genetic Code, Transcription, Translation | Prokaryotes | |
|
| 23 |
Go |
Q:
|
Which of the following correctly shows the RNA transcript of the coding strand of the DNA sequence below?
AGCTTATAC
TCGAATATG |
|
A
|
TGCUUTUTC |
B
|
UGCAAUAUG |
C
|
AGCAAUAUC |
D
|
AGCUUAUAC |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 24 |
Go |
Q:
|
Which of the following would inhibit mRNA synthesis?
I. a nonsense mutation
II. a mutation in DNA Polymerase III which prevents binding to DNA
III. loss of the promoter region |
|
A
|
III only |
B
|
I and III only |
C
|
I and II only |
D
|
I, II, and III |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 25 |
Go |
Q:
|
Uridine triphosphate (UTP) can undergo hydrolysis to form uridine diphosphate (UDP). In which components of a human cell would this be expected to occur? |
|
A
|
Rough ER |
B
|
Smooth ER |
C
|
Nucleus |
D
|
Lysosome |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 26 |
Go |
Q:
|
A mutation in the E site of a eukaryotic ribosome may result in which of the following? |
|
A
|
inability for tRNA to bind to the ribosome |
B
|
production of ultra-long polypeptide chains |
C
|
prevention of tRNA exit from the ribosome |
D
|
none of the above |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 27 |
Go |
Q:
|
The Hayflick limit is the maximum number of cell divisions that can be obtained from a normal cell population. Once a cell population reaches its Hayflick limit, the cells cease to divide and will eventually die. The Hayflick limit is determined primarily by which of the following? |
|
A
|
DNA Polymerase III |
B
|
RNA Polymerase |
C
|
telomeres |
D
|
free radical oxidation levels in the cell |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 28 |
Go |
Q:
|
The majority of mitochondrial proteins are synthesized on free ribosomes in the cytosol. The remainder of mitochondrial proteins are synthesized in the |
|
A
|
mitochondrial matrix. |
B
|
endoplasmic reticulum. |
C
|
nucleus. |
D
|
extracellular matrix. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 30 |
Go |
Q:
|
Which of the following statements is incorrect about introns? |
|
A
|
they are present in the functional, transcribed mRNA |
B
|
they are part of the primary transcript in eukaryotes |
C
|
they are composed of pyrimidine and purine residues |
D
|
they are excised from transcribed mRNA |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 31 |
Go |
Q:
|
The rough endoplasmic reticulum is so named because of ribosomes on its membrane. Which of the following statements best describes the way in which these ribosomes translate proteins? |
|
A
|
From the cytosol, into the intermembrane space of the endoplasmic reticulum |
B
|
From the cytosol, into the lumen of the endoplasmic reticulum |
C
|
From the intermembrane space of the endoplasmic reticulum, into the cytosol |
D
|
From the lumen of the endoplasmic reticulum, into the cytosol |
|
|
|
Tags:
Genetic Code, Transcription, Translation | Eukaryotic Cells | |
|
| 32 |
Go |
Q:
|
Which of the following is FALSE regarding proteins that are synthesized by free ribosomes in the cytosol? |
|
A
|
The proteins are likely to have their post-translational modifications be associated with the endoplasmic reticulum. |
B
|
The proteins can have functions in the nucleus. |
C
|
The proteins can have functions in the mitochondria. |
D
|
The proteins are likely to have folding assistance from chaperone proteins. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 33 |
Go |
Q:
|
In an experiment, RNA is being used instead of DNA as a PCR primer to replicate a DNA sequence. Which of the following primers would be most suitable for the sequence below?
3' AGCCGTGA 5' |
|
A
|
3' UCGGCACU 5' |
B
|
3' UCACGGCU 5' |
C
|
3' AGCCGUGA 5' |
D
|
3' AGUGCCGA 5' |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 34 |
Go |
Q:
|
A cell is having trouble transcribing rRNA and assembling ribosomes. Which of the following best explains this observation? |
|
A
|
The Golgi complex of the cell cannot produce vesicles. |
B
|
The cell has mitochondria lacking a cell wall. |
C
|
The cell is lacking a rough endoplasmic reticulum. |
D
|
The cell has a damaged nucleolus. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 35 |
Go |
Q:
|
The 5' cap is attached onto mRNA strands in the nucleus to help prevent their degradation in the cytosol. Which of the following would be expected from a cell with a deficient 5' cap attachment mechanism? |
|
A
|
mitochondrial protein translation would be unaffected |
B
|
overall transcription rate of the cell would be unaffected |
C
|
overall total protein in the cell would increase |
D
|
the cell would be unable to defend itself against viral infection |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 36 |
Go |
Q:
|
A number of genes lie on a DNA fragment with only one promoter at the beginning of the series. During transcription, the RNA polymerase either falls off after completing transcription of a gene or continues to the subsequent gene. Which genes would be transcription in the greatest abundance? |
|
A
|
The genes at the '3 end of the DNA strand |
B
|
The genes at the '5 end of the DNA strand |
C
|
The genes in the middle of the DNA strand |
D
|
All genes would be translated in equal abundance. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 37 |
Go |
Q:
|
A DNA sequence of 12,000 base pairs can code for a protein with a maximum length of approximately how many amino acids? |
|
A
|
4000 |
B
|
12,000 |
C
|
36,000 |
D
|
3,000 |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 38 |
Go |
Q:
|
Which of the following terms correlates with the fact that there is a multiplicity of three-codon combinations which specify a particular amino acid? |
|
A
|
non-ambiguous |
B
|
degeneracy |
C
|
specific |
D
|
universal genetic code |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 39 |
Go |
Q:
|
A particular endocrine cell type in the body secretes a substance with the formula X-R. X is the core molecule, and R is a glycan group. A certain subset of these cells are studied and it is found that the substance these cells produce is X, rather than X-R. This deficit likely relates to the: |
|
A
|
Nucleus. |
B
|
Golgi apparatus. |
C
|
Smooth ER. |
D
|
Mitochondria. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 40 |
Go |
Q:
|
A particular nucleotide sequence contains over 90% G and C nucleotides and only 10% A and T nucleotides. This strand likely: |
|
A
|
will likely not code for protein. |
B
|
is located in extranuclear DNA. |
C
|
has a relatively high melting temperature. |
D
|
will code for ribosomal RNA (rRNA). |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 44 |
Go |
Q:
|
Which of the following best describes how tRNA differs from mRNA? |
|
A
|
Transfer RNA uses adenine, guanine, uracil, and cytosine while messenger RNA uses adenine, guanine, thymine, and cytosine.
|
B
|
Transfer RNA uses adenine, guanine, thymine, and cytosine while messenger RNA uses adenine, guanine, uracil, and cytosine.
|
C
|
Transfer RNA has a complex loop structure while messenger RNA is usually a simple, linear strand.
|
D
|
In transfer RNA, anticodons are complementary to messenger RNA codons, while in messenger RNA, codons are anti-complementary to DNA triplets.
|
|
|
|
Tags:
Genetic Code, Transcription, Translation | Nucleic Acid Structure and Function | |
|
| 45 |
Go |
Q:
|
Which of the following is true regarding stop codons? |
|
A
|
Stop codons contain at least two of the same bases found in the start codon.
|
B
|
Stop codons can contain thymine in the messenger RNA.
|
C
|
The amino acid attached to a tRNA that recognizes a stop codon is nonpolar, and this contributes to the translation process ending.
|
D
|
The introduction of a premature stop codon can be due to both nonsense and missense mutations.
|
|
|
|
Tags:
Genetic Code, Transcription, Translation | DNA Replication and Repair | |
|
| 47 |
Go |
Q:
|
A fish species is found to have a genetic adaptation allowing it to live in far more acidic waters than other members of its family. If the adaptation did not come at the cost of any other functionality compared to other members of the family, what would have been required to occur during the evolution of this fish species? |
|
A
|
point mutation |
B
|
chromosomal translocation |
C
|
frameshift mutation |
D
|
gene duplication event |
|
|
|
Tags:
Genetic Code, Transcription, Translation | Evolution | |
|
| 48 |
Go |
Q:
|
Which of the following is the earliest step in transcription of eukaryotic DNA? |
|
A
|
unwinding of DNA helix |
B
|
assembly of the transcription initiation complex |
C
|
binding of the enzyme RNA ligase |
D
|
movement of RNA polymerase from the 5' to 3' direction |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 49 |
Go |
Q:
|
For which of the following point mutations could a premature stop codon result?
I) insertion of 15 nucleotides within the sequence
II) base-pair substitution in the middle of the sequence
III) insertion of 2 nucleotides within the sequence |
|
A
|
I and III only |
B
|
III only |
C
|
II and III only |
D
|
I, II, and III |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 50 |
Go |
Q:
|
UAA is a commonly found stop codon found in mRNA sequences. Which of the following sequences contains this stop codon? |
|
A
|
3'-CGCUAUUAA-5' |
B
|
3'-CGCUCUAUU-5' |
C
|
3'-AAUCAGGGU-5' |
D
|
3'-UUAUGGUAG-5' |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 51 |
Go |
Q:
|
Which of the following is incorrect regarding the genetic code? |
|
A
|
Three nucleotides code for a single amino acid. |
B
|
The code differs between prokaryotes and eukaryotes. |
C
|
There are 20 amino acids coded by the genetic code. |
D
|
There are more codons than the total number of amino acids. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 52 |
Go |
Q:
|
Which of the following is true regarding a transposon? |
|
A
|
They are composed of RNA. |
B
|
They are composed of both RNA and DNA. |
C
|
They are mobile units within a chromosome. |
D
|
They are required for chromosomal replication. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 54 |
Go |
Q:
|
The P site of a ribosome is where: |
|
A
|
the exit site from which tRNA leaves the ribosome. |
B
|
the site where tRNA enters the ribosome. |
C
|
the site on which the polypeptide is attached. |
D
|
the site which error checks polypeptide formation. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 55 |
Go |
Q:
|
An extraterrestrial genetic code is discovered which utilizes a set of five nucleotides and combines them to make codons of length 4. How many possible codons exist in this genetic code system? |
|
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 56 |
Go |
Q:
|
A particular DNA strand reads as follows: 5'-TAAGCCAA-3'. mRNA transcribed from this DNA would read: |
|
A
|
5'-ATTCGGTT-3'. |
B
|
5'-TTGGCTTA-3'. |
C
|
5'-AUUCGGUU-3'. |
D
|
5'-UUGGCUUA-3'. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 57 |
Go |
Q:
|
Which of the following is incorrect regarding the differences between eukaryotic and prokaryotic transcription and translation? |
|
A
|
Prokaryote ribosomes are composed of a 30S and 50S subunit; eukaryote ribosomes are composed of a 40S and 60S subunit. |
B
|
Both prokaryotic and eukaryotic ribosomes contain A, P, and E sites. |
C
|
Initiation factors are involved in both prokaryotic and eukaryotic translation. |
D
|
Both prokaryotes and eukaryotes produce ribosomes via the nucleolus. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 58 |
Go |
Q:
|
A frameshift mutation can take place with the:
I. insertion of a single nucleotide.
II. deletion of a single nucleotide.
III. deletion of 3 sequential nucleotides. |
|
A
|
I only |
B
|
II and III only |
C
|
I and II only |
D
|
I, II and III |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 59 |
Go |
Q:
|
Introns are unlikely to contain: |
|
A
|
coding segments of DNA. |
B
|
nucleotide sequences. |
C
|
regions of DNA which will be subsequently excised from mRNA. |
D
|
the sugar phosphate backbone of typical DNA molecules. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 60 |
Go |
Q:
|
In prokaryotic mRNA translation, the region of the ribosome in which tRNA first enters the ribosome is referred to as the: |
|
A
|
A site. |
B
|
P site. |
C
|
E site. |
D
|
S site. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 61 |
Go |
Q:
|
The genetic code of codons has been described as being a degenerate code. Degeneracy suggests: |
|
A
|
that there are explicit codons which code for the start and stop of a peptide sequence. |
B
|
that codons are universal among species, irrespective of kingdom. |
C
|
the presence of synonymous mutations. |
D
|
every codon can only code for a single amino acid. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 62 |
Go |
Q:
|
Chromatin found in a lightly-packed form that is readily available for transcription is referred to as: |
|
A
|
euchromatin. |
B
|
heterochromatin. |
C
|
synchromatin. |
D
|
prochromatin. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 64 |
Go |
Q:
|
Methylation of histones: |
|
A
|
is a very rare process within chromosomes. |
B
|
is related to telomere length and cellular aging. |
C
|
affects transcription of certain genes. |
D
|
is a component of the genetic code of chromosomes. |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 68 |
Go |
Q:
|
Which of the following best describes a release factor? |
|
A
|
a DNA base pairing which results in termination of an amino acid sequence |
B
|
a specific mRNA molecule |
C
|
a protein involved in post-translational modification of a completed protein |
D
|
a protein which facilitates the termination of translation |
|
|
|
Tags:
Genetic Code, Transcription, Translation | |
|
| 69 |
Go |
Q:
|
A strand-break temperature for a particular DNA molecule is defined as a temperature at which exactly 50% of the A-T bonds in a strand of DNA are split. If this temperature is 120 degrees celcius for a particular DNA strand, which of the following is true? |
|
A
|
greater than 50% of the C-G strands will be broken at the strand break temperature |
B
|
less than 50% of the C-G strands will be broken at the strand break temperature |
C
|
exactly 50% of the C-G strands will be broken at the strand break temperature |
D
|
we cannot know the status of the C-G strands from the information provided |
|
|
|
Tags:
Genetic Code, Transcription, Translation | Nucleic Acid Structure and Function | |
|
|
We can teach you how to crush the MCAT!
Learn More
|
