Chapter 17 - Gene Expression: Gene→Protein

Which component is not directly involved in translation? (a) mRNA (b) DNA (c) ribosomes (d) GTP (e) tRNA

(b) DNA

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

3' UCA 5'

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

3' UCA 5'.

RNA polymerase moves in which direction along the DNA?

3' → 5' along the template strand

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?

A gene from an organism can theoretically be expressed by any other organism.

The DNA codon AGT codes for an amino acid carried by a tRNA with the anticodon ______.

AGU

Which component is not directly involved in translation?

DNA

Why might a point mutation in DNA make a difference in the level of a protein's activity?

It might substitute an amino acid in the active site.

Why might a point mutation in DNA make a difference in the level of protein's activity?

It might substitute an amino acid in the active site.

Translation converts the information stored in ______ to ______.

RNA . . . a polypeptide

Which of the following enzymes is responsible for RNA synthesis?

RNA polymerase

In which of the following actions does RNA polymerase differ from DNA polymerase?

RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis.

As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs?

The tRNA that was in the A site moves into the P site.

Which of the following statements are true about protein synthesis in prokaryotes?

Translation can begin while transcription is still in progress.

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is

UUU.

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?

a deletion of 2 nucleotides

The shared genetic code of all life on Earth is evidence that ______.

all life shares a common ancestry

Peptide bonds form between ______.

amino acids

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the

bonding of the anticodon to the codon and the attachment of amino acids to tRNAs.

Accuracy in the translation of mRNA into the primary structure of the polypeptide depends on specificity in the

bonding of the anticodon to the codon and the attachment to amino acids to tRNAs.

Alternative RNA splicing

can allow the production of proteins of different sizes from a single mRNA.

Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes

excision of introns.

A mutation in which of the following parts of a gene is likely to be most damaging to a cell?

exon

The expressed (coding) regions of eukaryotic genes are called ______.

exons

What are the coding segments of a stretch of eukaryotic DNA called?

exons

The process by which genotype becomes expressed as phenotype is ______.

gene expression

What type of bonding is responsible for maintaining the shape of the tRNA molecule?

hydrogen bonding between base pairs

Transcription is the ______.

manufacture of a strand of RNA complementary to a strand of DNA

The RNA that is translated into a polypeptide is ______ RNA.

messenger

The region of DNA where RNA synthesis begins is the ______.

promoter

A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of a phenylalanine. The consequence of this for the cell will be that

proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

A mutation within a gene that will insert a premature stop codon in mRNA would ______.

result in a shortened polypeptide chain

Where is translation accomplished?

ribosomes

If a strand of DNA has the sequence AAGCTC, transcription will result in a(n) ______.

single RNA strand with the sequence UUCGAG

The absence of a terminator in transcription will result in ______.

the production of a longer RNA molecule

From the following list, which is the first event in translation in eukaryotes?

the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA

How many nucleotides make up a codon?

three

Choose the answer that has these events of protein synthesis in the proper sequence. 1. An aminoacyl-tRNA binds to the A site. 2. A peptide bond forms between the new amino acid and a polypeptide chain. 3. tRNA leaves the P site, and the P site remains vacant. 4. A small ribosomal subunit binds with mRNA. 5. tRNA translocates to the P site.

4, 1, 2, 5, 3

Which component is not directly involved in translation? a) tRNA b) DNA c) GTP d) mRNA e) ribosomes

DNA

Use the following information to answer the following questions. A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already. Where does tRNA #2 move to after this bonding of lysine to the polypeptide?

Exit tunnel

Which of the following is not true of RNA processing? a) RNA splicing can be catalyzed by spliceosomes. b) Ribozymes may function in RNA splicing. c) Exons are cut out before mRNA leaves the nucleus. d) A primary transcript is often much longer than the final RNA molecule that leaves the nucleus. e) Nucleotides may be added at both ends of the RNA.

Exons are cut out before mRNA leaves the nucleus.

Which of the following is not true of RNA processing? a) RNA splicing can be catalyzed by spliceosomes. b) Ribozymes may function in RNA splicing. c) Exons are cut out before mRNA leaves the nucleus. d) A primary transcript is often much longer than the final RNA molecule that leaves the nucleus. e) Nucleotides may be added at both ends of the RNA.

c) Exons are cut out before mRNA leaves the nucleus.

What is the correct order of the stages of translation?

initiation, codon recognition, peptide bond formation, translocation, termination

The correct sequence of events occurring during transcription is ______.

initiation, elongation, termination

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that

many noncoding intron stretches of nucleotides are present in mRNA.

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. this best explained by the fact that

many noncoding stretches of nucleotides are present in mRNA.

What is the smallest number of nucleotides that must be added or subtracted to alter the reading frame?

one

Use the following information to answer the following questions. A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already. Which enzyme causes a covalent bond to attach lysine to the polypeptide?

peptidyl transferase

Which of the following is the first event to take place in translation in eukaryotes? a) binding of the larger ribosomal subunit to smaller ribosomal subunits b) the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA c) base pairing of activated methionine-tRNA to AUG of the messenger RNA d) elongation of the polypeptide e) covalent bonding between the first two amino acids

the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA

Which of the following is the first event to take place in translation of eukaryotes?

the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA