Transcription

Question 1

What is the differences between RNA and DNA?

Answer 1

Ribose instead of deoxyribose
Uracil instead of thymine
Single stranded

Question 2

Name the 5 types of RNA

Answer 2

mRNA
rRNA
tRNA
snRNA
miRNA

Question 3

What is the role of mRNA?

Answer 3

Template for proteins synthesis

Question 4

What is the role of rRNA?

Answer 4

major compartment of ribosomes

Question 5

What is the role of tRNA?

Answer 5

carries amino acids in activated form to the ribosomes

Question 6

Describe RNA Synthesis

Answer 6

RNA produced by copying one strand of DNA
Catalysed by RNA polymerase using rNTPS realising pyrophosphate
NO PRIMER IS NEEDED
Nucleotides added to 3’OH

Question 7

Describe Transcription initiation

Answer 7

At the start units are marked by promoters that demined the start.
Initiation factor directs the enzymes to the correct initiation site
Core Enzyme alpha 2 Beta Beta’ Omega

Question 8

Describe Transcription initiation in prokaryotes

Answer 8

Pribnow Box ( AT rich region at -10)
TTGACA at -35

Question 9

Describe the start of Transcription

Answer 9

Binding to template causes DNA separation.
RNA synthesis occurs in the 5’ to 3’ dir antiparallel to DNA strand
Transient RNA/DNA complexes

Question 10

Describe transcription elongation

Answer 10

Termination signals tell the polymerase when to stop the DNA template.
One signal is palindromic GC rich followed by AT rich region
New RNA transcript formed in hairpin structure with a stem and loop

Question 11

Signals for termination are made from what?

Answer 11

Newly synthesized RNA

Question 12

In prokaryotes when does Transcription and Translation occur?

Answer 12

Together

Question 13

In Eukaryotes where does RNA synthesis occur?

Answer 13

in the nucleus

Question 14

In Eukaryotes where does translation occur?

Answer 14

in the cytoplasm

Question 15

Describe how eukaryote RNA is processed

Answer 15

polyA tail is added to 3’ end to increase stability and specifies export to cytoplasm
Addition of cap to 5’ end

Question 16

What are three factors that influence gene expression

Answer 16

Nuclear membrane
RNA processing
Complex transcriptional regulation

Question 17

What does splicing do?

Answer 17

removes introns ( non coding DNA) to allow synthesis of several proteins on one gene

Question 18

What codes for the splicing sites?

Answer 18

RNA sequence

Question 19

What performs the splicing?

Answer 19

The spliceosome

Question 20

How can transcription be controlled?

Answer 20

Interaction of RNA polymerase w/ promoter can be enhanced by activators or blocked by repressor.

In bacteria operon promoter controls this

Question 21

What is the name for gene that are expressed all the time?

Answer 21

Constitutive expression

Question 22

What is the name for gene that not expressed all the time?

Answer 22

Regulated expression

Question 23

Describe the regulation that is associated with Allolactose

Answer 23

Allolactose is an inducer of the operon which binds to the repressor and prevents binding to operator.
SO genes are on when lactose is present

Question 24

What do these bind to?
Basal Transcription factors
Regulatory Transcriptional factors

Answer 24

Basal- bind to promoters

Regulatory- bind to promotor-proximal elements and enhancers

Question 25

microRNA or miRNa does what?

Answer 25

regulates gene expression