Cundliffe 1 RNA transcription promoters

Question 1

Gene Expression

Answer 1

mRNA = Messanger RNA
⇨ to carry info to cytosol
DNA vs. RNA
5C & 4 Bases

DNA => mRNA=> Protein

Question 2

Translation :

Answer 2

– ability of RNA to translate & synth polypeptide/protein chain

Question 3

RNA bases :

Answer 3

A, U, G, C

• RNA is single stranded
• =amount of the 4 bases varies
• RNA in some viruses
• Non-stranded pairs for DNA not same in RNA e.g. G & U

Question 4

RNA Secondary Structure :

Answer 4

o Partially double stranded. (DS)
RNA stem-loops form helices 11 BP per 360’
1/2 helical turn

Question 5

Messanger RNA (mRNA):

Answer 5

• Carries genetic info copied from gene [DNA] Template for translation on ribosomes
• bacteria : some but not all need to get out of nuclear pore first

Question 6

Ribosomal RNA (rRNA):

Answer 6

Bacterial: 3 rRNA =2 large +1 small
Eukaryotic: 4 rRNA = 2 large & 2 small -> proteins to pin RNA in active state

Question 7

Transfer RNA (tRNA):

Answer 7

~76 nucleotides long, carry amino acids to ribosomes -> poly peptide chains
- each tRNA is dedicated to 1 of 20 amino acids. => some a.a. have 1+ tRNA’s

Question 8

RNA SYNTHESIS

Equation:

Answer 8

(RNA)n +NTP (RNA) n+1 +(ribonucloside triphosophate= substrate)

Question 9

RNA SYNTHESIS

Catalysed by:

Answer 9

RNA Polymerase (RNAP)

Question 10

Hydrolysis of PPi:

Answer 10

cleavage of P grp by pyrophosphatase => drives synthesis
Inorganic phyrophosphate (PPi) => 2 Pi

Question 11

RNA SYNTHESIS

REQUIES:

Answer 11

DS DNA template,  
 NTPs & Mg 2+ 
Synthesis: 5’ -> 3’
Partially completed by RNA
Highly processive.

Question 12

Differences to DNA synthesis

Answer 12

Primer: one, from new polymerase itself - not semi-conservative
Nucleases: no activity
Processivity: highly 1000’s
Only 1 DNA strand copied: complementary copying = hybridization analysis

Question 13

Template strand:

Answer 13

copied

Question 14

Coding Strand:

Answer 14

same seq as mRNA except T not U

-Anti parallel

Question 15

TRANSCRIPTION:
Bacteria:

Answer 15

Bacteria: genes close packed all relative orientations are possible

• > = divergent
• > -> = sequential

Question 16

TRANSCRIPTION:
Mammalians:

Answer 16

genes are so far apart that orientaion is irrelevent

RNA pol reads template 3’-5’, all nucleic acids made 5’-3’, RNA pol can ‘jump’

Question 17

Specific binding site for RNA pol

Answer 17

Upstream of coding region.

Question 18

Footprinting:

Answer 18

finding promoters, RNA pol protects DNA promoter region from digestion with DNase
- 10-15BP long
Differ: in appearance, although many of them approximate to a ‘consensus seq’

Question 19

Strong vs. Weak promoters:

Answer 19

strong promoters capture RNA pol more efficiently, is weak as less is needed.
Diff class = diff expression = temperol control therfore DNA seq is the same in all cells but different genes expressed to speciallise into different cell types e.g. embryogenisis