Chapter 19, Ribosomes and Transfer RNA Video Solutions, Molecular Biology

Problem 1

Draw rough sketches of the E. coli $30 \mathrm{~S}$ and $50 \mathrm{~S}$ ribosomal subunits and show how they fit together to form a $70 \mathrm{~S}$ ribosome.

Rabeya Zahid

Numerade Educator

06:08

Draw a diagram of a hypothetical eukaryotic polysome in which nascent protein chains are visible. Identify the 5 '- and $3^{\prime}$ 'ends of the mRNA and use an arrow to indicate the direction the ribosomes are moving along the mRNA. Use $\mathrm{N}$ and $C$ to indicate the amino and carboxyl ends of one of the growing polypeptides.

Bryan Lynn

Numerade Educator

05:43

Problem 2

Draw rough sketches of interface views of both $50 \mathrm{~S}$ and $30 \mathrm{~S}$ ribosomal subunits. Point out the rough positions of tRNAs in the A, P, and E sites.

Rabeya Zahid

Numerade Educator

00:21

Problem 2

Draw a diagram of a hypothetical prokaryotic gene being transcribed and translated simultaneously. Show the nascent mRNAs with ribosomes attached, but do not show nascent proteins. With an arrow, indicate the direction of transcription.

Sam Limsuwannarot

Numerade Educator

01:59

Problem 3

What parts of the tRNAs interact with the $30 \mathrm{~S}$ subunit? With the $50 \mathrm{~S}$ subunit?

Shiksha Dutta

Numerade Educator

05:32

Problem 3

You are investigating a $\mathrm{tRNA}^{\text {Phe }}$ whose charging specificity appears to be affected by a C11-G24 base pair in the D stem. Design two experiments to show that changing this base pair changes the charging specificity of the tRNA. The first experiment should be a biochemical one using an in vitro reaction. The second should be a genetic one performed in vivo.

Jennifer Stoner

Numerade Educator

05:26

Problem 4

Consider the process of bringing a new aminoacyl-tRNA to the A site, as revealed by $x$-ray crystallography. Describe the probable effects of each of the following mutations on speed and fidelity of translation:
a. A mutation in the $16 \mathrm{~S} \mathrm{rRNA}$ that facilitates "domain closure" in the $30 \mathrm{~S}$ subunit.
b. A mutation in the acceptor stem of the tRNA that inhibits the change in conformation that normally helps the tRNA bend into the $\mathrm{A} / \mathrm{T}$ state.
c. A mutation in switch I of EF-Tu that strengthens its binding to the acceptor stem of tRNA.
d. Mutating His 84 of EF-Tu to Alanine.

Dennis Howard

Numerade Educator

03:34

Problem 4

Why is it important that the anticodons of the tRNAs in the $A$ and $P$ sites approach each other closely?

Kendrick Buford

Numerade Educator

03:34

Problem 5

Why is it important that the acceptor stems of the tRNAs in the $A$ and $P$ sites approach each other closely?

Kendrick Buford

Numerade Educator

03:42

Problem 6

Describe the process of two-dimensional gel electrophoresis described in this chapter. In what way is two-dimensional superior to one-dimensional electrophoresis?

Ryan Hood

Numerade Educator

02:46

Problem 7

Present plausible hypotheses to explain how the following antibiotics interfere with translation. Present evidence for each hypothesis.
a. Streptomycin
b. Paromomycin

Aadit Sharma

Numerade Educator

01:49

Problem 8

How can x-ray diffraction data rule out ribosomal proteins as the active site in peptidyl transferase?

Rachel Peterson

Numerade Educator

Problem 9

Outline the evidence for the importance of the $2^{\prime}-\mathrm{OH}$ of the terminal adenosine of the peptidyl-tRNA in the P site in transpeptidation. How is this hydroxyl group likely to participate in transpeptidation?

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02:46

Problem 10

Outline the evidence for the importance of the $2^{\prime}-\mathrm{OH}$ of A2451 of the $23 \mathrm{~S} r \mathrm{rRNA}$ in transpeptidation. How is this hydroxyl group likely to participate in transpeptidation?

Aadit Sharma

Numerade Educator

08:49

Problem 11

How do we know the base of A2451 (A2486 in H. marismortui) is not important in transpeptidation?

Susan Hallstrom

Numerade Educator