Transcription + Translation

Question 1

Where is the TATA box located and how many BP away?

Answer 1

25-35 BP upstream

Question 2

How common is the TATA box in cells

Answer 2

only present in 24% of genes

Question 3

Which direction does transcription occur?

Answer 3

5’ to the 3’ direction

Question 4

What molecules do RNA polymerase attach?

Answer 4

ribonucleoside triphosphate

Question 5

What does DNA polymerase requires to take effect

Answer 5

Requires a primer as it needs an O-H group to bond to

Question 6

error rate in transcription?

Answer 6

1 in 100,000

Question 7

what does polycystronic mean

Answer 7

one strand of mRNA can code for multiple proteins

Question 8

which end does the poly a tail attach to?

Answer 8

3’ end

Question 9

how does the 5’ cap attach?

Answer 9

7-methyl guanosine triphosphate attaches via a 5’ to 5’ triphosphate link

Question 10

What amino acid starts translation?

Answer 10

AUG - methionine

Question 11

What is the starting amino acid in bacteria and why is this good?

Answer 11

N-formylmethionine - allows immune system to identify foreign bacterial cells

Question 12

what is the site order in translation?

Answer 12

A site then P site then E site

Question 13

What are the three stop codons

Answer 13

UGA UAA UAG

Question 14

which site do release factor bind to?

Answer 14

A site

Question 15

What is wobble and where does it occur

Answer 15

occurs at 1st base on anticodon, 3rd base of codon (mismatch of amino acids

Question 16

what are the 3 types of rna

Answer 16

mRNA - carries RNA to ribosomes for translation - make up 5% or rna
rRNA - ribosomal rna (most common) combines with other enzymes and proteins for protein synthesis
tRNA - smallest amount - transfer amino acids during protein synthesis

Question 17

what are the differences between DNA and RNA

Answer 17

RNA: has a uracil not a thymine

is ribose sugar and - deoxyribose lacks a hydroxyl on the second group

Question 18

what are the 3 RNA polymerases and what do they do

Answer 18

Polymerase 1 - transcribes ribosomal RNA
Poly 3 - transcribed tRNA
poly 2 - transcribes mRNA, microRNA and non-coding RNAs

Question 19

what is tata box

Answer 19

promoter element composed of T’s and A’s

Question 20

what happens in splicing

Answer 20

removal of introns (non-coding sequences)

Question 21

what happens in polyadenylation

Answer 21

addition of many A’s at the 3’ end which reduces chance of enzymatic degradation and helps with identification and termination of transcription

Question 22

what is a 5’ cap

Answer 22

7 - methylguanosine ppp added to 5’ end which stabilising the mRNA

Question 23

what is CpG island and why are they relevant

Answer 23

stretches of DNA where C is followed by G - appear t have an effect on promotor regions. In x inactivation CpG island is methylated which stops expression of a gene

Question 24

how are introns removed

Answer 24

by a spliceosomewhich produces a lariat loop with an OH at the 3’ end

Question 25

describes the steps in mRNA packaging

Answer 25

RER with ribosomes 
to Golgi (cis - trans) 
secretion into the plasma membrane

Question 26

what is a disulphide bridge

Answer 26

bond between two cysteine residues

Question 27

describe the process of insulin production

Answer 27

preproinsulin - signal sequence is cleaved off in the pancreas in B cells
proinsulin - disulphide bonds form in the ER
Insulin - the connecting C-peptide loop is cut away in secretory granules by proteases

Question 28

which enzymes add amino acids on the 3’ end of newly synthesised tRNA molecules

Answer 28

aminoacyl - tRNA synthetases (tRNA ligase)

Question 29

how is the correct amino acid added to polypeptide chain

Answer 29

anticodon is specific and there is proof reading glelemtn by the RNA synthetases