Chapter 17

The anticodon of a particular tRNA molecule is ________.

complementary to the corresponding mRNA codon

Which of the following occurs in prokaryotes but not in eukaryotes?

concurrent transcription and translation

If the sequence in the coding strand of DNA for a particular amino acid is 5'AGT3', then the anticodon on the corresponding tRNA would be ________.

5'ACU3'

Use the following information to answer the question below.A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3'(mRNA). The following charged transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form. tRNA AnticodonAmino AcidGGCCGUUGCCCGACGCGGProlineAlanineThreonineGlycineCysteineAlanine The anticodon loop of the first tRNA that will complement this mRNA is

3' GGC 5'

Put the following events of bacterial transcription in chronological order. 1.Sigma binds to the promoter region. 2.The double helix of DNA is unwound, breaking hydrogen bonds between complementary strands. 3.Sigma binds to RNA polymerase. 4.Sigma is released. 5.Transcription begins.

3, 1, 2, 5, 4

Use this model of a eukaryotic transcript to answer the following question(s).E = exon and I = intron5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'Which components of the previous molecule will also be found in mRNA in the cytosol?

5' UTR E1 E2 E3 E4 UTR 3'

How does termination of translation take place?

A stop codon is reached.

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

AAA

Codons are three-base sequences that specify the addition of a single amino acid. How do eukaryotic codons and prokaryotic codons compare?

Codons are a nearly universal language among all organisms.

In the figure associated with this question, what is the function of the AGU on the loop of the tRNA?

It base pairs with a codon of mRNA.

Use this model of a eukaryotic transcript to answer the following question(s).E = exon and I = intron5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'Suppose that an induced mutation removes most of the 5' end of the 5' UTR of an mRNA. What is most likely to happen?

Removal of the 5' UTR also removes the 5' cap and the mRNA will quickly degrade.

The ribosome-binding site of prokaryotes is also known as the ________.

Shine—Dalgarno sequence

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its 5' cap and poly-A tail. Which of the following would you expect her to find?

The molecule is digested by enzymes because it is not protected at the 5' end.

How are RNA hairpin turns related to transcriptional termination in E. coli?

The turns are formed from complementary base pairing and cause separation of the RNA transcript and RNA polymerase.

The figure associated with this question represents a tRNA that recognizes and binds a particular amino acid (in this instance, phenylalanine). Which codon on the mRNA strand codes for this amino acid?

UUC

You want to engineer a eukaryotic gene into a bacterial colony and have it expressed. What must be included in addition to the coding exons of the gene?

a bacterial promoter sequence

What is responsible for termination of transcription in eukaryotic protein-coding genes?

a polyadenylation, or poly(A), signal

Use this model of a eukaryotic transcript to answer the following question(s).E = exon and I = intron5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'When the spliceosome binds to the transcript shown above, it can attach ________.

at certain sites along an intron

Ribosomes can attach to prokaryotic messenger RNA ________.

before transcription is complete

David Pribnow studied the base sequences of promoters in bacteria and bacterial viruses. He found two conserved regions in these promoters (the −10 box and the −35 box). These two regions of the promoter ________.

bind the sigma subunit that is associated with RNA polymerase

Which of the following processes is central to the initiation of transcription in bacteria?

binding of sigma to the promoter region

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

binding of the anticodon to the codon and the attachment of amino acids to tRNAs

In comparing DNA replication with RNA transcription in the same eukaryotic cell, only DNA replication ________.

incorporates the entire template molecule in the product

Translation directly involves ________.

mRNA, tRNA, ribosomes, and GTP

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase II is transcription of ________.

protein-coding genes

What molecules in the spliceosome catalyze the intron removal reactions?

ribozymes

Death cap mushrooms produce a substance called alpha-amanitin. Alpha-amanitin efficiently blocks synthesis of mRNA, but not of tRNA or rRNA, in eukaryotic organisms. This is possible because alpha-amanitin efficiently interferes with ________.

the action of RNA polymerase II, but not RNA polymerase I or III

What ensures that the correct amino acid is added during translation?

the anticodon of a properly formed aminoacyl tRNA

Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?

the phosphate bonds in the nucleotide triphosphates that serve as substrates

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that ________.

the rules for base pairing between the third base of a codon and tRNA are flexible