Exam 9: The Molecular Biology of Translation

A portion of an mRNA attached to a ribosome reads: 5′ GACCAUUUUUGA 3′ If a tRNA with a histidine amino acid attached is in the P site of the ribosome, a tRNA with which amino acid attached will enter the A site?

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Question 1

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Polypeptides must be sorted after translation. Does protein sorting occur in both prokaryotes and eukaryotes? Describe the process of protein sorting and explain how the signal sequence is involved. What would you expect to see if the signal sequence has been mutated or deleted?

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Protein sorting is a process that uses signal sequences of amino acids at the N-terminal end of a polypeptide to sort proteins and direct them to their cellular destinations. Protein sorting is needed in bacterial cells because of the many proteins specifically destined for the cell membrane. In eukaryotes, however, protein sorting is far more complex than in bacteria; proteins are dispatched to particular cellular organelles, such as the chloroplast, mitochondrion, lysosome, and nucleus, and certain proteins are secreted from the cells. If the signal sequence is mutated, proteins may not be secreted or processed properly and will begin to accumulate within the cell. Ultimately, this will result in cell death and impaired protein secretion.

Heinz Fraenkel-Conrat induced point mutations in the genes encoding coat proteins of TMV and looked for changes in the resulting proteins. By examining the effect of single-base changes in the mRNA on the amino acid sequence, Conrat proved that __________.

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Khorana used synthetic mRNAs to determine genetic code possibilities. To do so, he translated synthetic mRNA in vitro in the presence of individual 14C-labeled amino acids. What polypeptide did he identify using the repeating dinucleotide poly-UG?

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Question 4

In eukaryotes, the initiation factor proteins eIF1A and eIF3 join with ________ to form the preinitiation complex.

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Question 5

Ribosomal subunits are measured in which units, which describe the speed of sedimentation of a substance during centrifugation?

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Question 6

What reaction provides the energy for the eukaryotic ribosome to search for the start AUG during the process of scanning?

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Question 7

A polycistronic mRNA contains multiple _______________.

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Question 8

Given the following mRNA sequence, which of the following mRNAs would encode a protein with a different sequence of amino acids? 5′ - AUG CAG UUA GCG UGC UAG - 3′

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Question 9

In the ER, misfolded proteins are identified and bound by what molecules?

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Question 10

In a polyribosome, which end of the mRNA would have the shortest polypeptides?

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Question 11

________ help control ribosome formation and binding of the initiator tRNA.

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Question 12

In the unlikely event that a tRNA has been charged with the wrong amino acid, what high-fidelity enzyme is likely to blame?

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Question 13

How does the eukaryotic initiation complex locate the true start codon?

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Question 14

Sidney Brenner proved that the triplet code is, in fact, nonoverlapping. Assuming a nonoverlapping code, how many complete codons would the following sequence encode before encountering a stop codon? 5′ - AUGCGAUUAUAGUGC - 3′

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Question 15

If you are designing an antibiotic that inhibits peptide bond formation, what enzyme would you target?

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Question 16

A portion of mRNA attached to a ribosome reads: 5′ GACCAUUUUUGA 3′ In the polypeptide produced, what amino acid will be attached to the amino group of the histidine encoded by this mRNA?

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Question 17

Given the following mRNA sequence, what is the amino acid sequence for the corresponding polypeptide? 5′ - AUG CGA UUU GGG UGC UAG - 3′

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Question 18

The preinitiation complex forms in bacteria when the start codon is recognized through binding of 16srRNA and what region of mRNA?

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Question 19

A mutagen has introduced a frame-shift mutation by adding one nucleotide base. Which of the following could be a reversion mutation for this particular mutant?

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Question 20

Showing 1 - 20 of 55

Exam 9: The Molecular Biology of Translation

A portion of an mRNA attached to a ribosome reads: 5′ GACCAUUUUUGA 3′ If a tRNA with a histidine amino acid attached is in the P site of the ribosome, a tRNA with which amino acid attached will enter the A site?

Polypeptides must be sorted after translation. Does protein sorting occur in both prokaryotes and eukaryotes? Describe the process of protein sorting and explain how the signal sequence is involved. What would you expect to see if the signal sequence has been mutated or deleted?

Heinz Fraenkel-Conrat induced point mutations in the genes encoding coat proteins of TMV and looked for changes in the resulting proteins. By examining the effect of single-base changes in the mRNA on the amino acid sequence, Conrat proved that __________.

Khorana used synthetic mRNAs to determine genetic code possibilities. To do so, he translated synthetic mRNA in vitro in the presence of individual 14C-labeled amino acids. What polypeptide did he identify using the repeating dinucleotide poly-UG?

In eukaryotes, the initiation factor proteins eIF1A and eIF3 join with ________ to form the preinitiation complex.

Ribosomal subunits are measured in which units, which describe the speed of sedimentation of a substance during centrifugation?

What reaction provides the energy for the eukaryotic ribosome to search for the start AUG during the process of scanning?

A polycistronic mRNA contains multiple _______________.

Given the following mRNA sequence, which of the following mRNAs would encode a protein with a different sequence of amino acids? 5′ - AUG CAG UUA GCG UGC UAG - 3′

In the ER, misfolded proteins are identified and bound by what molecules?

In a polyribosome, which end of the mRNA would have the shortest polypeptides?

________ help control ribosome formation and binding of the initiator tRNA.

In the unlikely event that a tRNA has been charged with the wrong amino acid, what high-fidelity enzyme is likely to blame?

How does the eukaryotic initiation complex locate the true start codon?

Sidney Brenner proved that the triplet code is, in fact, nonoverlapping. Assuming a nonoverlapping code, how many complete codons would the following sequence encode before encountering a stop codon? 5′ - AUGCGAUUAUAGUGC - 3′

If you are designing an antibiotic that inhibits peptide bond formation, what enzyme would you target?

A portion of mRNA attached to a ribosome reads: 5′ GACCAUUUUUGA 3′ In the polypeptide produced, what amino acid will be attached to the amino group of the histidine encoded by this mRNA?

Given the following mRNA sequence, what is the amino acid sequence for the corresponding polypeptide? 5′ - AUG CGA UUU GGG UGC UAG - 3′

The preinitiation complex forms in bacteria when the start codon is recognized through binding of 16srRNA and what region of mRNA?

A mutagen has introduced a frame-shift mutation by adding one nucleotide base. Which of the following could be a reversion mutation for this particular mutant?

The Molecular Basis of Heredity, Variation, and Evolution

Transmission Genetics

Cell Division and Chromosome Heredity

Gene Interaction

Genetic Linkage and Mapping in Eukaryotes

Genetic Analysis and Mapping in Bacteria and Bacteriophages

Dna Structure and Replication

Molecular Biology and Transcription and Rna Processing

The Integration of Genetic Approaches: Understanding Sickle Cell Disease

Chromosome Structure

Gene Mutation, Dna Repair, and Homologous Recombination

Chromosome Aberrations and Transposition

Regulation of Gene Expression in Bacteria and Bacteriophages

Regulation of Gene Expression in Eukaryotes

Forward Genetics and Recombinant Dna Technology

Applications of Recombinant Dna Technology and Reverse Genetics

Genomics: Genetics From a Whole-Genome Perspective

Cytoplasmic Inheritance and the Evolution of Organelle Genomes

Developmental Genetics

Genetic Analysis of Quantitative Traits

Population Genetics and Evolution

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