Chapter 3 (transcription and RNA Processing)

Question 1

RNA that’s only found in eukaryotes ?

Answer 1

Heterogenous nuclear RNA and small nuclear RNA

Question 2

Protein required for initiation of transcription ?

Answer 2

Sigma

Question 3

Protein required for termination of transcription only in prokaryotes

Answer 3

Rho factor

Question 4

Actinomycin D mechanism ?

Answer 4

Binds to the DNA preventing transcription

Question 5

Inhibitor of prokaryotic RNA polymerase ?

Answer 5

Rifampin

Question 6

Inhibitor of eukaryotic RNA polymerase ll ?

Answer 6

Alpha amanitin toxin in mushrooms

Question 7

Functions of RNA polymerases l , ll , lll in eukaryotes ?

Answer 7

RNAP l : synthesis of all rRNA except 5S rRNA
RNAP ll : synthesis of hnRNA , mRNA and some snRNA
RNAP ll : symthesis of tRNA and 5S rRNA

Question 8

Diseases result from problems in splicing ?

Answer 8

Beta thalassemia , SLE and Marfan syndrome

Question 9

Examples for alternative splicing of eukaryotic pre-mRNA

Answer 9

Membrane Ig versus secreted Ig
Tropomyosin and troponin T variants of muscle proteins
Dopamine receptors in the brain

Question 10

Shiga toxin mechanism ?

Answer 10

Inactivates the 28S rRNA in the 60S subunit of the eukaryotic ribosome preventing tRNA bonding to the ribosome ,halting the protein synthesis

Question 11

tRNA binding site to the amino acid ?

Answer 11

3’ OH of the 5’-CCA-3’ at the 3’ end of tRNA

Question 12

Example for RNA editing ?

Answer 12

Cytosine to uracil deamination in the apoprotein gene , apoprotein B100 expressed from liver become B48 in the intestine , CAA sequence become UAA which is stop codon producing shorter apoprotein B48 form

Question 13

Site of rRNA ,tRNA and mRNA synthesis ?

Answer 13

rRNA —-> nucleolus

mRNA and tRNA —-> nucleoplasm ( euchromatin )