Molecular Biology (6)

Question 1

What is the process of tRNA synthesis?

Answer 1

RNase P cleaves 5’ end of each tRNA sequence
RNase D cleaves near 3’ end of each tRNA sequence - then trims to 3’ end of precursor
tRNA nucleotidyl transferase adds CCA to 3’ end of precursor

Question 2

How many copies of tRNA precursors are in each primary transcript?

Answer 2

Multiple

Question 3

How many copies of rRNA precursors are in each primary transcript?

Answer 3

One of each type

Question 4

Name the different types of prokaryotic rRNAs

Answer 4

16S
23S
5S

Question 5

What is the process of rRNA synthesis?

Answer 5

RNase III cleaves near ends of precursors

Other endonucleases trim precursor ends

Question 6

How many RNA polymerases do eukaryotes have?

Answer 6

5

Question 7

What are the types of eukaryotic RNA polymerase and what do they transcribe?

Answer 7

RNA polymerase I - rRNA genes
RNA polymerase II - all protein-coding genes and some snRNA genes
RNA polymerase III - tRNA genes and some snRNA genes
Mitochondrial RNA polymerase - mitochondrial genes
Chloroplast RNA polymerase - chloroplast genes

Question 8

What is the order of rRNAs in a eukaryotic RNA polymerase I transcription unit?

Answer 8

18S - 5.8S - 28S

Question 9

Describe the processing of eukaryotic pre-rRNA

Answer 9

Primary transcript cut - gives mature rRNAs
Methylation of specific ribose 2’-OH
Conversion of specific uridine residues to pseudouridine

Question 10

Which transcription factor is used by all 3 eukaryotic polymerases?

Answer 10

TBP (TATA binding protein)

Question 11

Name the core promoter elements and their ligands for RNA polymerase II

Answer 11

BRE - TFIIB binds
TATA box - TBP binds
Inr (initiator) - TFIID binds
DPE (downstream promoter elements) - TFIID binds