Transcription

Question 1

DNA topoisomerase

Answer 1

Alters/resets supercoiled dna

Question 2

What signals replication to begin in prokaryotes?

Answer 2

The sigma factor which is part of a complex with rna polymerase signals the start of transcription

Question 3

What is abortive initiation?

Answer 3

At the beginning of transcription where the synthesis of short rna strands happens as a result of the sigma factor and RNAP clashing. RNAP escapes away from sigma factor and carries on.

Question 4

How does the frequency with which transcription is successfully carried out determined?

Answer 4

The sigma factor binding to the consensus sequence can determine how successful transcription will be as RNAP/sigma complex can become unbound if not bound tightly to begin with.

Question 5

How many genes in the human genome?

Answer 5

22 000 (3 billion base pairs)

Question 6

What biological functions do rna molecules that have been transcribed from non-coding dna have?

Answer 6

Non-coding rna, ribosomal rna and transfer rna

Question 7

What genes are transcribed by RNAP I

Answer 7

5.8s, 18s and 28s rna gene

Question 8

What genes are transcribed by RNAP II?

Answer 8

All protein-coding genes, plus snoRNA genes, miRNA genes, siRNA genes, IncRNA genes and most snRNA genes

Question 9

What genes are transcribed by rnap III

Answer 9

tRNA, 5s RNA, some snRNA and genes from other small RNAs

Question 10

What does rnap require a set of GTF’s?

Answer 10

As rnap can not recognise a gene promoter on its own

Question 11

What determines the start point of transcription in eukaryotes?

Answer 11

Core promoter elements interacting with rnap II gtf’s

Question 12

What’s the role of TFIID in transcription initiation?

Answer 12

TBP subunit recognises TATA box

TAF subunit recognises other DNA sequences near the transcription start point and regulates binding to dna binding TBP

Question 13

What’s the role of TFIIB in the initiation of transcription?

Answer 13

Recognises BRE element in promoters and accurately positions rna polymerase at the start of transcription

Question 14

What’s the role of TFIIF in the initiation of transcription?

Answer 14

Stabilises rnap’s interaction with TBP and TFIIB; helps attract TFIIE and TFIIH

Question 15

What’s the role of TFIIH is the initiation of transcription?

Answer 15

Unwinds dna at the start point, phosphorylates ser5 of the rnap ctd and releases rnap from promoter

Question 16

What is transcriptomics and proteomics?

Answer 16

An analysis of mRNA’s by microarray or RNA-seq. provides a snapshot of gene expression

Question 17

What are transcriptional activators?

Answer 17

Modular proteins with multiple distinct domains.