DNA

Question 1

Which are purines and which pyrimidine

Answer 1

A and G are purine so 2 rings

T and C are pyrimidine with 1 ring

Question 2

What bonds between nucleotides

Answer 2

phosphodiester

Question 3

What is on 5’ end and what on the 3’ end

Answer 3

5’ is phosphate

3’ is hydroxyl

Question 4

what are the hydrogen bonds between bases

Answer 4

C and G = 2

T and A = 1

Question 5

What is the hershey case experiment

Answer 5

grow virus in 2 different broths one rich in radioactive phosphate(in DNA) one radioactive sulfur (in proteins)
viruses then allowed to infect E.coli and then centrifuged
pellet contains the bacteria, supernatant virus
Bacterial pellet was radioactive with phosphate not sulphur proving that the DNA was inserted by the virus not the protein so the DNA contains the genetic material

Question 6

What direction doen DNA polymerase work

Answer 6

adds new sugar ti backbone at 3’ end. only synthesises from 5’ to 3’

Question 7

What happens to the lagging strand

Answer 7

okazaki fragments so not continuous replication. Primers are removed ribonuclease H and polymerase recognises the gaps and fills in

Question 8

What is transcription

Answer 8

RNA polymerase binds to primer region and single strand mRNA is synthesised

Question 9

what is the role of promoter

Answer 9

activity of the promoter determines how much of the protein is produced. It is unidirectional

Question 10

Ways to protest mRNA

Answer 10

introns spliced out
poly A tail added (AAAAAA)
RNA cap

Question 11

What is the transcriptome

Answer 11

section of genome to be transcribed to RNA

Question 12

heterochromatin and euchromatin

Answer 12

hetero is inactive transcriptionally dark and dense but euchromatin is loose and active so RNA polymerase gets in

Question 13

Centromere ?

Answer 13

repetive DNA sequence where spindles attach in cell division

Question 14

Telomere ?

Answer 14

soecialised DNA sequence at ends of linear chromosome that maintain integrity maintained by telomerase

Question 15

origin of replication ?

Answer 15

where replication starts not at the ends but in the middle

Question 16

chemical Mutation

Answer 16

EMS and ENU are alkylating agents covalently bind to modify DNA single base pair change

Question 17

Xray mutation cause?

Answer 17

induce breakdown of DNA backbone so lose fragments

Question 18

UV mutation cause?

Answer 18

causes thymine to covalently bond to each other causing it to be read incorrectly

Question 19

process of translation?

Answer 19

tRNA binds to specific complementary codon, peptide bonds form between amino acids that are joint to tRNA on large subunit
stop codon causes release factor to bind, end of peptide

Question 20

role of large and small subunit?

Answer 20

large : peptide bond formation

small: decoding mRNA

Question 21

what does the location of the ribosome mean

Answer 21

if on ER then it is fro secretion, if free floating it is for local use only

Question 22

what is the N and C terminus?

Answer 22

N is with the amine group

C is end with carboxyl

Question 23

how is a peptide bond formed?

Answer 23

a condensation reaction, catalysed by peptide transferase

Question 24

What affect does urea have on protein?

Answer 24

denatures it, if removed it reverts back

Question 25

What is the quaternary structure?

Answer 25

when 2 subunits bind to form a dimer, can be identical - homotetramer or different: heterotetramer

Question 26

Type one and type 2 transmembrane protein difference?

Answer 26

1; has N terminus extracellular | 2: N terminus intracellular

Question 27

What are lipid modifications?

Answer 27

covalently attached lipid t help protein bind. Intracellular = acylation and prenylation Extracellular = GPI anchor

Question 28

Role of glycosylation?

Answer 28

provides sticky surface, adhesive properties sugar can bind to amino acids

Question 29

Phosphorylation role?

Answer 29

kinases catalyse, need ATP, gives a negative charge

Question 30

How is GTP activated and inactivated

Answer 30

by adding and losing a phosphate

Question 31

What is an SRP used for?

Answer 31

ensuring the protein goes to the correct destination. the receptor is complementary to the signal sequence in the amino acid chain

Question 32

Steps in protein modification when at ER

Answer 32

1. arrives at ER lumen,directed by the signal sequence to the SRP 2. once bound SRP released and recycled 3. ribosome and protein are at a translator channel and it opens 4. protein fed through and signal sequence is cleaved off

Question 33

What is the role of a chaperone?

Answer 33

ensure the proteins fold correctly as bind to the hydroponic regions that are visible and shouldn't be and cause hydrolysed to result in change in folding

Question 34

2 types of chaperone and differenced

Answer 34

Hsp60 - when already folded but wrong, enters a chamber that is then capped and ATP needed Hsp70 - used when it is actively folding

Question 35

What if still not folding after chaperone?

Answer 35

targetted and tagged which ubiquitin, causes it to be degraded in proteasome and cleaved into peptides