Biochem 72

Question 1

What is the direction of protein synthesis?

Answer 1

N-terminus to C-terminus

Question 2

DNA and RNA are synthesized in which direction?

Answer 2

5’ -> 3’

Question 3

Which end of the incoming nucleotide contains the triphosphate group?

Answer 3

5’

Question 4

How do drugs blocking DNA replication work?

Answer 4

They have modified 3’ OH, preventing addition of the next nucleotide (“chain termination”)

Question 5

What is the target of the 3’hydroxyl attack?

Answer 5

Triphosphate group

Question 6

What is the mRNA start codon?

Answer 6

AUG or rarely GUG

Question 7

AUG codes for what in eukaryotes?

Answer 7

Methionine

Question 8

AUG codes for what in prokaryotes?

Answer 8

Formylmethionine (f-met)

Question 9

What are the mRNA stop codons?

Answer 9

UGA, (U Go Away)
UAA, (U Are Away)
UAG (U Are Gone)

Question 10

What is the TATA box?

Answer 10

Promoter region that binds transcription factors and RNA Polymerase II during the initiation of transcription.

(Located about 25 bases upstream from beginning of coding region)

UW: 2030

Question 11

Promoter mutations can cause what?

Answer 11

Abnormal gene expression by altering the ability of RNA Polymerase II and transcription factors to bind.

UW: 2030

Question 12

What occurs at enhancer regions on genes?

Answer 12

Transcription factors bind

Question 13

What occurs at silencer regions on genes?

Answer 13

Negative regulators (repressors) bind

Question 14

Homeobox genes code for what?

Answer 14

DNA-binding transcription factors that play an important role in morphogenesis.

UW: 2015

Question 15

Explain the Kozak sequence

Answer 15

When the methionine (AUG) codon is positioned near the beginning of an mRNA molecule and is surrounded by the Kozak sequence, it serves as an initiator for translation (i.e. mRNA binding to ribosomes).

UW: 2086