Question 1

Which statement is true about the release factors in the termination of translation in E.coli?

Accepted Answer

A) The release factors methylate the termination codon which blocks the codon from being recognized by a tRNA. 
B) The release factors induce conformational changes at the A and P sites of the ribosome that cause the termination of translation. 
C) After recognizing the termination codon,the release factors cause the hydrolysis of the peptidyl-tRNA. 
D) The release factors are modulators that bind to the ribosomal subunits and cause them to dissociate from each other. 
A) The release factors methylate the termination codon which blocks the codon from being recognized by a tRNA. 
B) The release factors induce conformational changes at the A and P sites of the ribosome that cause the termination of translation. 
C) After recognizing the termination codon,the release factors cause the hydrolysis of the peptidyl-tRNA. 
D) The release factors are modulators that bind to the ribosomal subunits and cause them to dissociate from each other.

Question 2

Chain elongation consists of three steps: (1)positioning the correct aminoacyl-tRNA to the A site,(2)forming the peptide bond and (3)________.

Accepted Answer

A) dissociation of the 30S and 50S subunits 
B) removal of the fMet-tRNAfmet from the complex 
C) moving the mRNA along one codon 
D) All of the above 
E) None of the above 
A) dissociation of the 30S and 50S subunits 
B) removal of the fMet-tRNAfmet from the complex 
C) moving the mRNA along one codon 
D) All of the above 
E) None of the above

Question 3

At the beginning of translocation,the growing peptide chain is attached to tRNA located at the ________ on the ribosome.

Accepted Answer

A) E site only 
B) A site and part of the P site 
C) A site only 
D) P site only 
A) E site only 
B) A site and part of the P site 
C) A site only 
D) P site only

Question 4

High levels of ribosome synthesis are maintained in prokaryotes and eukaryotes by ribosomal genes that have

Accepted Answer

A) clustering in the nucleolus. 
B) strong promoters. 
C) multiple copies. 
D) Both B and C above. 
A) clustering in the nucleolus. 
B) strong promoters. 
C) multiple copies. 
D) Both B and C above.

Question 5

Tryptophan synthesis is controlled by a repressor protein which is activated by a corepressor which is

Accepted Answer

A) leader peptide. 
B) promoter locus. 
C) operator locus. 
D) tryptophan. 
A) leader peptide. 
B) promoter locus. 
C) operator locus. 
D) tryptophan.

Question 6

Proteins destined to enter a cell membrane contain a signal peptide at the C-terminal end of the peptide.

Accepted Answer

A) True 
 B)False

Question 7

Termination (stop)codons are recognized by specific proteins that cause newly synthesized peptides to be released from the ribosome.

Accepted Answer

A) True 
 B)False

Question 8

Puromycin is an antibiotic that inhibits protein synthesis because

Accepted Answer

A) it binds a ribosomal protein. 
B) it inhibits peptidyl transferase. 
C) it binds to the 50S subunit preventing translocation. 
D) it looks like aminoacyl-tRNA and binds to the A site. 
E) it binds to the E site. 
A) it binds a ribosomal protein. 
B) it inhibits peptidyl transferase. 
C) it binds to the 50S subunit preventing translocation. 
D) it looks like aminoacyl-tRNA and binds to the A site. 
E) it binds to the E site.

Question 9

At the end of the initiation step,the ribosome has a vacant

Accepted Answer

A) A site. 
B) P site. 
C) mRNA site. 
D) tRNA. 
E) All of the above. 
A) A site. 
B) P site. 
C) mRNA site. 
D) tRNA. 
E) All of the above.

Question 10

In eukaryotes the initiation codon is the first AUG triplet from the 5' end of mRNA.

Accepted Answer

A) True 
 B)False

Question 11

Streptomycin can be used clinically because it inhibits bacterial protein synthesis but not eukaryotic protein synthesis.

Accepted Answer

A) True 
 B)False

Question 12

More energy is used to form a single peptide bond than is required for the bond formation alone.

Accepted Answer

A) True 
 B)False

Question 13

The ribosome distinguishes the initiator AUG codon from other AUG codons that specify methionine residues internally in a protein because there are Shine-Dalgarno sequences just upstream from initiator codons and not upstream of internal methionine codons.

Accepted Answer

A) True 
 B)False

Question 14

The link between an activated amino acid and tRNA is an ________ bond between the ________ of the amino acid and a hydroxyl group of the tRNA.

Accepted Answer

A) ester;carboxylate group 
B) amide;carboxylate group 
C) amide;amino group 
D) imine;amino group 
A) ester;carboxylate group 
B) amide;carboxylate group 
C) amide;amino group 
D) imine;amino group

Question 15

The anticodon of tRNAala can bind to three different codons for alanine (GCU,GCC and GCA)because

Accepted Answer

A) there are different bases at the 5' end position of the anticodon. 
B) there are different bases at the 3' end position of the anticodon. 
C) the base at the 5' position of the anticodon is I and is the wobble position. 
D) the base at the 3' position of the anticodon is I and is the wobble position. 
A) there are different bases at the 5' end position of the anticodon. 
B) there are different bases at the 3' end position of the anticodon. 
C) the base at the 5' position of the anticodon is I and is the wobble position. 
D) the base at the 3' position of the anticodon is I and is the wobble position.

Question 16

Which statement is not true about the "wobble" position?

Accepted Answer

A) It is in the 5' position on the anticodon. 
B) Base pairing other than Watson-Crick base pairing is allowed at this position. 
C) It allows anticodons to recognize more than one codon. 
D) Often has inosinate at the 3' position of the codon. 
A) It is in the 5' position on the anticodon. 
B) Base pairing other than Watson-Crick base pairing is allowed at this position. 
C) It allows anticodons to recognize more than one codon. 
D) Often has inosinate at the 3' position of the codon.

Question 17

Aminoacyl-tRNA synthetase must catalyze the attachment of the correct amino acid to the correct tRNA if protein synthesis is to be accurate.

Accepted Answer

A) True 
 B)False

Question 18

Coupling of transcription and translation occurs in both animal and bacterial cells.

Accepted Answer

A) True 
 B)False

Question 19

Methionine and tryptophan are the only amino acids that do not have multiple codons.

Accepted Answer

A) True 
 B)False

Question 20

The genes for rRNA tend to have very strong promoters.

Accepted Answer

A) True 
 B)False

Exam 22: Protein Synthesis

Which statement is true about the release factors in the termination of translation in E.coli?

Chain elongation consists of three steps: (1)positioning the correct aminoacyl-tRNA to the A site,(2)forming the peptide bond and (3)________.

At the beginning of translocation,the growing peptide chain is attached to tRNA located at the ________ on the ribosome.

High levels of ribosome synthesis are maintained in prokaryotes and eukaryotes by ribosomal genes that have

Tryptophan synthesis is controlled by a repressor protein which is activated by a corepressor which is

Proteins destined to enter a cell membrane contain a signal peptide at the C-terminal end of the peptide.

Termination (stop)codons are recognized by specific proteins that cause newly synthesized peptides to be released from the ribosome.

Puromycin is an antibiotic that inhibits protein synthesis because

At the end of the initiation step,the ribosome has a vacant

In eukaryotes the initiation codon is the first AUG triplet from the 5' end of mRNA.

Streptomycin can be used clinically because it inhibits bacterial protein synthesis but not eukaryotic protein synthesis.

More energy is used to form a single peptide bond than is required for the bond formation alone.

The ribosome distinguishes the initiator AUG codon from other AUG codons that specify methionine residues internally in a protein because there are Shine-Dalgarno sequences just upstream from initiator codons and not upstream of internal methionine codons.

The link between an activated amino acid and tRNA is an ________ bond between the ________ of the amino acid and a hydroxyl group of the tRNA.

The anticodon of tRNAala can bind to three different codons for alanine (GCU,GCC and GCA)because

Which statement is not true about the "wobble" position?

Aminoacyl-tRNA synthetase must catalyze the attachment of the correct amino acid to the correct tRNA if protein synthesis is to be accurate.

Coupling of transcription and translation occurs in both animal and bacterial cells.

Methionine and tryptophan are the only amino acids that do not have multiple codons.

The genes for rRNA tend to have very strong promoters.

Introduction to Biochemistry

Water

Amino Acids and the Primary Structures of Proteins

Proteins: Three-Dimensional Structure and Function

Properties of Enzymes

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Electron Transport and Atp Synthesis

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

DNA Replication, repair, and Recombination

Transcription and RNA Processing

Filters

The link between an activated amino acid and tRNA is an bond between the of the amino acid and a hydroxyl group of the tRNA.