Lecture 10

Question 1

Prokaryotic ribosomes find initiations sites via complementary binding of the ___S RNA component of the ____S subunit to the ____-____ box.

Answer 1

16S

30S

Shine-Dalgarno

Question 2

Eukaryotic ribosomes initiate translation via ___-dependent scanning carried out by initiation factor ____ on the ____S ribosomal subunit. They can also initiate translation via _____, facilitated by an element that articulates with the ____S ribosomal subunit and cooperatively binds just upstream of the AUG codon.

Answer 2

Cap-dependent

eIF4E

40S

IRES

40S

Question 3

_______ (an aminoglycoside) is an antibiotic that targets the ___S subunit and inhibits initiation and elongation.

Answer 3

Streptomycin

30S

Question 4

_____ is a tyrosine analogue that causes early termination in translation for BOTH prokaryotes and eukaryotes.

Answer 4

Puromycin

Question 5

______ is characterized by sore throat, difficulty swallowing, and a thick gray coating in the throat (pseudomembrane). The treatment is ______, which blocks the _____ aspect of translation in prokaryotes.

Answer 5

Diphtheria

Erythromycin

Elongation

Question 6

_____ toxin is composed of two fragments:

1. Fragment __ causes the toxin to be internalized.
2. Fragment __ disrupts the elongation aspect of translation by modifying the eukaryotic factor ____.

Answer 6

Diphtheria

B

A

eEF2

Question 7

_____ is a toxin derived from castor beans. It too is composed of two aspects:

1. ___ chain binds cell surface receptor, mediating uptake of the toxin in to the cell.
2. ___ chain depurinates ____S chain of rRNA at specific A residue.

Answer 7

B chain

A chain

28S

Question 8

Termination of translation occurs when release factors, which resemble _____ in structure, bind the stop codon and cause ______ (reaction) of the carboxy terminus AA, allowing it to dissociate.

Answer 8

tRNA

Hydrolysis

Question 9

Translation requires a total of _____ high energy bonds per AA; half are required in the ____ step, and half in the ____ step.

Answer 9

4

Charging

Elongation

Question 10

_____ is a protein that binds intracellular Fe2+. When Fe2+ levels are high, translation of this protein occurs. When levels are low, the protein binds the ____, blocking translation.

Answer 10

Ferritin

IRE

Question 11

Hereditary _________ - ______ syndrome is caused by a mutation in the _____ (the protein cannot bind and inhibit translation), which results in overproduction of Ferritin. The excess Ferritin leaks out of the cell and into the blood. This is an example of specific translational control.

Answer 11

Hereditary Hyperferritinemia - cataract syndrome

IRE

Question 12

eIF2 requires GTP to complex with Met-tRNA I for translation initiation. Normally, ____ is the factor responsible for exchanging GDP for GTP on eIF2. However, if eIF2 is phosphorylated by a kinase, it binds ____, and traps it, so less is available to facilitate the GDP-GTP exchange. _____ white matter or leukodystrophy can arise from mutations in any of the 5 subunits of _____, and can be exacerbated by head trauma.

Answer 12

eIF2B

eIF2B

Vanishing white matter (VWM)

eIF2B

Question 13

_____ is the translation initiation factor that binds the 5’ cap of mRNA. It’s function is upregulated by _____ of itself or of ___-BP. When the latter is _______, it dissociates from the initiation factor (when bound, it sequesters it.)

Answer 13

eIF4E

Phosphorylation

4E-BP

Phosphorylated

Question 14

Erythromycin and Chloramphenicol are of the _____ class of antibiotic. They target the _____S subunit of prokaryotic ribosomes and inhibit _____.

Answer 14

Macrolides

50S

Translocation

Question 15

Tetracycline, like streptomycin, targets the ____S subunit of prokaryotic ribosomes. It inhibits binding of AA-tRNA to the __-site.

Answer 15

30S

A-site