Exam 9: The Molecular Biology of Translation

Prokaryotes and eukaryotes show differences in posttranscriptional modifications of mRNA. What are these differences, and why do eukaryotes show more modifications than prokaryotes?

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Question 1

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In bacteria, the coupling of transcription and translation allows ribosomes to engage in translation of the 5' region of mRNAs whose 3' end is still under construction by RNA polymerase. Translation of the mRNA transcripts begins before transcription is complete, since there are no membrane- bound organelles to provide physical separation of the two processes. In eukaryotes, however, transcription and translation are uncoupled. Transcription takes place in the nucleus, where pre- mRNA is processed to form mature mRNA. Translation occurs in the cytoplasm after release of mature mRNA. Because the processes are physically (and temporally) separated, the mRNA receives a 5' cap and 3' tail to make the transcript stable and to help the ribosome locate the transcript when it exits the nucleus.

Bacteria group their genes such that they share a single promoter and the mRNA transcript synthesizes several different polypeptides. Collectively, these are referred to as _________mRNAs, which are part of the operon system.

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Question 2

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polycistronic

Thanks to flexible base pairing, the wobble nucleotides in anticodons can be one or more of the standard RNA nucleotides or which modified nucleotide?

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inosine (I)

Identification of ribosomal proteins involves two- dimensional gel electrophoresis, which separates the proteins on the basis of ________ .

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Question 4

Which mRNA below would code for a premature stop codon from the following amino acid sequence? N-Met- Gln- Leu- Arg- Cys-C

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Question 5

A tRNA in the P site of the ribosome will enter the _________site after translocation of the ribosome.

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Question 6

In the Golgi complex, what type of protein modification will signal the polypeptide destination by determining the receptor to which the peptide will bind?

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Question 7

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

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Question 8

Using mathematical reasoning, a triplet genetic code gives a possible _different codons, while a doublet genetic code would yield __ different codons. Thus, the triplet code accounts for 20 known amino acids and indicates redundancy in the genetic code.

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Question 9

Eighteen of the amino acids have two or more synonymous codons. Which two amino acids are the exceptions?

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Question 10

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

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Question 11

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

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Question 12

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 13

How is a tRNA able to recognize its proper mRNA codon?

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Question 14

Elongation factors translocate the ribosome in the 3' direction by a distance of______ .

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Question 15

What would you expect to find bound to the stop codon at the A site?

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Question 16

What does it mean for two codons to be synonymous?

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Question 17

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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Question 18

A polycistronic mRNA contains multiple_________ .

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Question 19

What result would you expect if a mutation eliminates one of the four arms of a tRNA?

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Question 20

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Exam 9: The Molecular Biology of Translation

Prokaryotes and eukaryotes show differences in posttranscriptional modifications of mRNA. What are these differences, and why do eukaryotes show more modifications than prokaryotes?

Bacteria group their genes such that they share a single promoter and the mRNA transcript synthesizes several different polypeptides. Collectively, these are referred to as _________mRNAs, which are part of the operon system.

Thanks to flexible base pairing, the wobble nucleotides in anticodons can be one or more of the standard RNA nucleotides or which modified nucleotide?

Identification of ribosomal proteins involves two- dimensional gel electrophoresis, which separates the proteins on the basis of ________ .

Which mRNA below would code for a premature stop codon from the following amino acid sequence? N-Met- Gln- Leu- Arg- Cys-C

A tRNA in the P site of the ribosome will enter the _________site after translocation of the ribosome.

In the Golgi complex, what type of protein modification will signal the polypeptide destination by determining the receptor to which the peptide will bind?

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

Using mathematical reasoning, a triplet genetic code gives a possible _______different codons, while a doublet genetic code would yield ________ different codons. Thus, the triplet code accounts for 20 known amino acids and indicates redundancy in the genetic code.

Eighteen of the amino acids have two or more synonymous codons. Which two amino acids are the exceptions?

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

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

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

How is a tRNA able to recognize its proper mRNA codon?

Elongation factors translocate the ribosome in the 3' direction by a distance of______ .

What would you expect to find bound to the stop codon at the A site?

What does it mean for two codons to be synonymous?

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?

A polycistronic mRNA contains multiple_________ .

What result would you expect if a mutation eliminates one of the four arms of a tRNA?

The Molecular Basis of Heredity, Variation, and Evolution

Transmission Genetics

Cell Division and Chromosome Heredity

Inheritance Patterns of Single Genes and Gene Interaction

Genetic Linkage and Mapping in Eukaryotes

Genetic Analysis and Mapping in Bacteria and Bacteriophage

Dna Structure and Replication

Molecular Biology of Transcription and Rna Processing

Chromosome Chapter Title Tbd

Gene Mutation, Dna Repair, and Homologous Recombination

Chromosome Chapter Title Tbd

Regulation of Gene Expression in Bacteria and Bacteriophage

Regulation of Gene Expression in Eukaryotes

Analysis of Gene Function by Forward Genetics and Reverse Genetics

Recombinant Dna Technology and Its Applications

Genomics: Genetics From a Whole-Genome Perspective

Organelle Inheritance and the Evolution of Organelle Genomes

Developmental Genetics

Genetic Analysis of Quantitative Traits

Population Genetics and Evolution at the Population, Species, and Molecular Levels

Filters

Using mathematical reasoning, a triplet genetic code gives a possible _different codons, while a doublet genetic code would yield __ different codons. Thus, the triplet code accounts for 20 known amino acids and indicates redundancy in the genetic code.