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- 1. Multiple Choice
The codon table can be used to determine amino acids coded for by a nucleotide sequence.
It is correct to state that
A - identical amino acid sequences are found in all organisms
B - the genetic code is degenerate with respect to Met.
C - the codon GGU adds Trp to a polypeptide chain.
D - the DNA template sequence GAA codes for Leu.
- 2. Multiple Choice
The genetic code is described as a degenerate code. This means that
A - in almost all organisms the same DNA triplet is transcribed to the same amino acid.
B - some amino acids may be encoded by more than one codon
C - a single nucleotide cannot be part of two adjacent codons
D - three codons are needed to specify one amino acids
- 3. Multiple Choice
Consider the following sequence of six amino acids that make up part of a polypeptide:
phe --- leu --- pro --- val --- tyr --- ala
Another mutation within the original resulted in a shortened protein. The protein was truncated (cut short) after the amino acid valine, as shown below:
phe --- leu --- pro --- val
This truncated protein resulted from the codon
A - UAU changing to UAA
B - UAC changing to UGC
C - GUA changing to UGA
GUG changing to UGG
- 4. Multiple Choice
In humans, Duchenne muscular dystrophy (DMD) is caused by mutations in the dystrophin-encoding DMD gene. The DMD gene contains 79 exons. In some patients, duplication of one exon occurs.
If the number of nucleotides in the duplicated exon is divisible by three, the
A - transcribed mRNA will contain many stop codons.
B - length of each of the 79 exons will increase by three nucleotides.
C - translated protein will be longer than the dystrophin protein found in a person without DMD.
D - dystrophin of these patients will show one amino acid change in the sequence compared to normal dystrophin.
- 5. Multiple Choice
The codon table can be used to determine the sequence of amino acids coded for by a nucleotide sequence.
The following nucleotide occurs on the template strand of a DNA molecule.
AAA GCT ACC TAT CGG TTA
In a mutation, the eighth nucleotide in this sequence was changed from C to T. What would be the result of this mutation?
A - The peptide chain would be shortened.
B - The third amino acid would change from Thr to Ile.
C - The fourth amino acid would change from Ile to Tyr.
D - There would be no change in the amino acid sequence.
- 6. Multiple Choice
The following nucleotide sequence occurs on the template strand of a DNA molecule.
AAA GCT ACC TAT CGG TTA
In a mutation, a T was inserted after the fourth nucleotide on the given template strand. The result of this mutation would be that
A - all amino acids in this entire sequence would change.
B - only the first amino acid in the sequence would change.
C - only the second amino acid in the sequence would change.
D - all amino acids after the first in the sequence would change.
- 7. Multiple Choice
Transcription of a structural gene can be initiated by the
A - presence of DNA polymerase.
B - arrival of mRNA at a ribosome.
C - increase in concentration of amino acids in the cytosol of a cell.
D - absence of a protein that is usually attached to an operator for that structural gene.
- 8. Multiple Choice
Ricin is a naturally occurring, powerful poison that affects eukaryotic organisms. Large mammals that ingest small amounts of ricin can die within three to five days. Studies have concluded that ricin stops the movement of a ribosome along a specific molecule. This specific molecule has been labelled Molecule X in the diagram.
What is the name of molecule X?
A - rRNA
B - tRNA
C - mRNA
D - pre-mRNA
- 9. Multiple Choice
Ricin is a naturally occurring, powerful poison that affects eukaryotic organisms. Large mammals that ingest small amounts of ricin can die within three to five days. Studies have concluded that ricin stops the movement of a ribosome along a specific molecule. This specific molecule has been labelled Molecule X in the diagram.
Eukaryotic organisms die from ricin poisoning because the ricin immediately causes
A - nerve damage to motor neurons
B - the process of mitosis in the cells to stop
C - irreversible damage to DNA in the nuclei of cells
D - the process of protein synthesis in cells to stop
- 10. Multiple Choice
Tryptophan is an amino acid that is produced by many bacteria. Genes that code for the production of tryptophan are found on bacterial DNA and together are called the trp operon.
In the process of gene regulation, a repressor protein (trp repressor) binds to the trp operon. When such binding occurs, the process of tryptophan production stops. This is illustrated in the diagram.
When the trp repressor binds to the trp operon, which one of the following enzymes would be blocked from functioning normally?
A - RNA polymerase
B - DNA polymerase
C - endonuclease
D - DNA ligase
- 11. Multiple Choice
Tryptophan is an amino acid that is produced by many bacteria. Genes that code for the production of tryptophan are found on bacterial DNA and together are called the trp operon.
In the process of gene regulation, a repressor protein (trp repressor) binds to the trp operon. When such binding occurs, the process of tryptophan production stops. This is illustrated in the diagram.
Which one of the following factors would increase the concentration of the trp repressor in bacterial cells?
A - low concentrations of tryptophan
B - high concentrations of tryptophan
C - high concentration of DNA ligase
D - low concentration of DNA polymerase
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