Role Of DNA And RNA In Protein Synthesis

Question 1

Nuclei acid bases

Answer 1

Purines: adenine and guanine
Pyrimidines: cytosine, thymine and uracil

Question 2

Bond formation between 2 bases

Answer 2

Phosphodiester bond:

- between C3 and C4

Question 3

Why deoxyribose

Answer 3

Oxygen attacks the phosphorus inside the deoxyribose

Ribose sugar is less stable

Question 4

Difference in structure of nucleotides in DNA/RNA

Answer 4

OH in RNA

H in DNA

Question 5

Chargaff’s ‘rules’

Answer 5

%A = %T
%G = %C
%G = %(C + 5-MeC)

Question 6

What bonds from when base pairs interact

Answer 6

Hydrogen bonds

Question 7

Semi-conservative theory

Answer 7

DNA strands break into two, and separate
mRNA binds bases to the strands and build a complementary start to the template strand
This forms half new and half old
(Semi-conservative)

Question 8

DNA polymerase III

Answer 8

Addition of a base, losing pyrophosphate

Question 9

Synthesis requires primers

Answer 9

RNA polymerase: need primer, primase (synthesis)

DNA polymerase extends primer

Question 10

Okazaki fragments

Answer 10

Lagging strand, discontinuous, need for 2 primers

Question 11

DNA Ligase

Answer 11

Ligates the DNA together

Question 12

DNA topoisomerase IV

Answer 12

Corrects tangling is the DNA

Decatenation

Question 13

Central dogma of RNA, DNA and proteins

Answer 13

DNA (replication) involving tRNA, rRNA and snRNA transcribed to RNA (or back to DNA by reverse transcription). RNA can be replication or editing, which leads to translation to a protein

Question 14

Codons

Answer 14

3 nucleotides in a codon

4^3: 64 creating 20 amino acids

Question 15

Genetic code rules

Answer 15

Methionine: AUG start
STOP: UAA, UGA and UAG
3rd position often doesn’t matter
1st position changes result in similar Chem
Degenerate and universal

Question 16

RNA Polymerase

- structure

Answer 16

Sigma proteins recognise the place where transcription takes place

Question 17

Genes and promoters

- how it works

Answer 17

RNA polymerase recognises the promoter

Unwinds from position -10 and RNA synthesis starts at +1

Question 18

Initiation of transcription

- process

Answer 18

Coding and template strand
Sigma protein binds to the ribosome
RNA polymerase bound to unwound DNA, and start site RNA synthesis begins (ATP needed)

Question 19

The ribosome

- structure

Answer 19

Large and small subunit

mRNA feeds into the ribosome

Question 20

Chemistry of translation

- process

Answer 20

tRNA is brought into the ribosome attached to a specific amino acid, the amino acids are then lined side to side, catalysing a peptide bond between them forming a polypeptide chain

Question 21

DNA gyrase

Answer 21

Supercooling the DNA