Protein Structure and Translation

Enzymatic catalysis of the peptide bond between the growing polypeptide and the next incoming amino acid takes place in which binding site? a. A site b. P site c. combined A and P sites d. E site

a. A site

Referring to the figure, what is the codon (5'>3') that specifies the addition of Arg (amino acid argenine) to the polypeptide? a. AGA b. CUU c. UGG d. GAA e. UCU

a. AGA

Which step occurs in the P site of the ribosome during translation? a. The tRNA carrying the growing polypeptide moves to this site as the ribosome slides to the next codon. b. An incoming charged tRNA binds to this site. c. None of the other answer options is correct. d. An uncharged tRNA is ejected from this site as the ribosome slides to the next codon.

a. The tRNA carrying the growing polypeptide moves to this site as the ribosome slides to the next codon.

The ribosome ______ subunit has _______ binding sites for tRNA molecules. a. large; three b. large; four c. small; two d. small; three e. large; two

a. large; three

Ribosomes in prokaryotes and eukaryotes are: a. similar in structure and translate using the same genetic codes. b. identical in structure but translate using different genetic codes. c. identical in structure and translate using the same genetic code. d. similar in structure and translate using different genetic code.

a. similar in structure and translate using the same genetic codes.

Binding sites for tRNA are located in: a. the large ribosomal subunit. b. the small ribosomal subunit. c. both ribosomal subunits. d. neither ribosomal subunit.

a. the large ribosomal subunit.

Which of the answer choices occurs in the E site of the ribosome during translation? a. An incoming charged tRNA binds to this site. b. An uncharged tRNA is ejected from this site as the ribosome slides to the next codon. c. The tRNA carrying the growing polypeptide moves to this site as the ribosome slides to the next codon. d. None of the other answer options is correct.

b. An uncharged tRNA is ejected from this site as the ribosome slides to the next codon.

Once the molecule shown here is "charged," the outlined region labeled ______ will form complementary base pairs with the codon in the ________ in the A site of the ribosome. a. A; amino acid b. C; mRNA c. B; amino acid d. A; mRNA

b. C; mRNA

How is the amino acid held on the charged tRNA? a. It can be a combination of all bond types. b. covalent bond c. hydrogen bonds

b. covalent bond

The unfolding of a protein by heat or chemical treatment is referred to as: a. uncoupling. b. denaturation. c. hydrolysis. d. depolymerization. e. disaggregation.

b. denaturation.

When a charged tRNA is about to bind to the vacant A site of a ribosome, where is the growing polypeptide? a. in the A site b. in the P site c. in the E site d. The polypeptide is equally likely to be in any of the three sites.

b. in the P site

How many aminoacyl-tRNA synthetase enzymes must be present in cells to properly synthesize proteins? a. 3, one for each base in a codon b. 64, one for each possible codon c. 20, one for each amino acid d. 4, one for each base in the mRNA

c. 20, one for each amino acid

The interactions between amino acids are major factors in determining the shape of a protein. These interactions can be affected by the environment surrounding a protein. Which factor would have an effect on the shape of a protein? a. the concentrations of ions present in the environment b. whether the other molecules in the environment are predominantly hydrophilic or hydrophobic c. All of these choices are correct. d. the temperature of the environment.the pH of the environment

c. All of these choices are correct.

This image represents _____________ and _______________ is attached at the outlined region labeled ______. a. an minoacyl tRNA synthase; an anticodon; C b. an aminoacyl tRNA synthase; an amino acid; A c. a tRNA; an amino acid; A d. a tRNA; an amino acid; C e. a folded protein; an amino acid; A

c. a tRNA; an amino acid; A

Assuming A-U and G-C pairing between the anticodon and the codon, what anticodon in tRNAMet would pair with the codon 5′-AUG-3′? a. 5′-AUG-3′ b. 5′-UAC-3′ c. 5′-GUA-3′ d. 5′-CAU-3′ e. 5′-ATG-3′

d. 5′-CAU-3′ Two paired strands of nucleic acids should be antiparallel, so G on the 3′ end of the codon should be paired with C on the 5′ end of anticodon; the middle U with A; and A on the 5′ end of the codon with U on the 3′ end of the anticodon.

Which step occurs in the A site of the ribosome during translation? a. An uncharged tRNA is ejected from this site as the ribosome slides to the next codon. b. The tRNA carrying the growing polypeptide moves to this site as the ribosome slides to the next codon. c. None of the other answer options is correct. d. An incoming charged tRNA binds to this site.

d. An incoming charged tRNA binds to this site.

Which of the following is the actual event that translates the language of nucleic acids (the sequence of bases, A, T (U), C, and G) to the language of proteins (determining which amino acid will be added to the polypeptide)? a. release of the finished polypeptide at the stop codon b. binding of charged tRNA to the ribosome A site c. establishing the correct reading frame by the ribosome d. attachment of the appropriate amino acid to the tRNA by aminoacyl tRNA synthetase e. catalysis of a new peptide bond from the growing polypeptide to the next amino acid

d. attachment of the appropriate amino acid to the tRNA by aminoacyl tRNA synthetase

In the figure, which box encloses the codon currently at the P site of the ribosome? a. box D b. box C c. box A d. box B

d. box B

In the figure, which box encloses the anticodon currently at the A site of the ribosome? a. box B b. box A c. box D d. box C

d. box C

Proteins that prevent inappropriate folding of newly synthesized proteins are called: . a enzymes. b. ribosomes. c. polymerases. d. chaperones. e. synthetases.

d. chaperones.

The fully folded structure of a functional protein composed of a single polypeptide chain is referred to as: a. primary. b. quaternary. c. secondary. d. tertiary.

d. tertiary.

Referring to the figure, what is the anticodon of the next tRNA to enter the A site? a. 5'CUU3' b. 3'UGG5' c. 5'GAA3' d. 3'GAA5' e. 3'CUU5'

e. 3'CUU5'

Most proteins retain metabolic activity when denatured. false true

false