Module 2.3

Question 1

DNA monomers

Answer 1

nitrogenous base, deoxyribose, phosphate group

Question 2

RNA monomers

Answer 2

Nitrogenous base, ribose, phosphate group

Question 3

What are purines

Answer 3

Nitrogenous bases
2 rings
Adenine, guanine and Uracil

Question 4

What are pyrimidines

Answer 4

Nitrogenous bases
1 ring
Thymine and Cytosine

Question 5

bond name between nucleotides and where it is

Answer 5

Phosphodiester bond
Between Phosphate group and pentose sugar

Question 6

ADP monomers

Answer 6

Adenine
2 phosphate groups
Ribose

Question 7

ATP monomers

Answer 7

Adenine
3 phosphate groups
Ribose

Question 8

DNA structure

Answer 8

2 chains of polynucleotides
Chains run in opposite directions (antiparallel)
hydrogen bonds between nitrogenous bases (A-T 2 H bonds C-G 3 H bonds)
double helix
5 end is where the phosphate is bonded to C5
3 end in where the phosphate is bonded to C3
as bases are inside the coding is protected

Question 9

How to precipitate DNA

Answer 9

Mash up fruit (breaks cell wall)
Add detergent (breaks down plasma membrane)
Mix with water
Slowly pour cold ethanol into test tube
DNA precipitates out of solution

Question 10

Why is DNA replication semi-conservative

Answer 10

After a replication the new DNA contains 1 original and 1 new polynucleotide chain

Question 11

Process of DNA replication

Answer 11

Helicase enzyme breaks H bonds between nitrogenous bases leaving 2 single strands with exposed nitrogenous bases
Free DNA nucleotides join with the complimentary base pair on the original strand
DNA polymerase catalyses the addition of the new nucleotide bases in the 5-3 direction

Question 12

Direction of DNA polymerase and what this affects

Answer 12

5 3 direction
Polynucleotide running in the other direction (lagging strand) is catalysed in Okazaki fragment
Leading strand is catalysed continuously

Question 13

Triplet code meaning

Answer 13

3 nitrogenous bases code for 1 amino acid

Question 14

Non-overlapping meaning

Answer 14

Each nitrogenous is only used once to code for an amino acid

Question 15

Degenerate meaning

Answer 15

For the amino acids there are more than one triplet codes that can produce it
reduces the effect of point mutations

Question 16

Universal meaning

Answer 16

In all creatures the same bases code for the same amino acids

Question 17

Transcription process

Answer 17

Helicase unzips the double helix by breaking H bonds
Free RNA nucleotides complimentary base pair with the bases on the template DNA strand
RNA polymerase catalyses the formation of temporary H bonds between the RNA and DNA nucleotides
The mRNA separates from the DNA and travels out of the nucleus (through nuclear pores) to a ribosome

Question 18

Translation process

Answer 18

mRNA attaches to a ribosome
tRNA with complimentary anticodon to the codon on the mRNA brings the correct amino acid
anticodon and complimentary codon temporarily H bond
The ribosome moves over the mRNA and when 2 amino acids are next to each other a peptide bond forms

Question 19

Why a double helix forms

Answer 19

A purine always pairs with a pyrimidine so the width of the DNA is the same throughout allowing to twist