Genes Expression and Cell Division

Question 1

Structure of DNA

Answer 1

Polmertoic nucleic acid
Deoxyribose - 5C sugar
Nitrogen base - purine (A + G), pyramidine (C/T)
Phosphate group

Right handed double helix

Question 2

What links adjacent nucleotides in a polynucleotide chain?
What links base pairs in the helix?

Answer 2

3’-5’ phosphodiester bonds

Hydrogen bodes

Question 3

What proteins form a complex with DNA to form chromatin

Answer 3

Histone and acidic non-histone proteins

Question 4

What is the structure of a chromosome

Answer 4

Histone and DNA linked to form nucleosomes
Long strings of nucleosomes are compacted into a solenoid - (helical structure)
Solenoids arranged in loops attached at intervals to a non-histone protein scaffold

Question 5

What % of DNA encodes for genes?

Answer 5

<10%

Question 6

What are the classes of DNA in human genome

Answer 6

1. Single cope DNA - nucleotide sequence is represented only once per haploid genome - 75% of genome
2. Dispersed repetitive DNA families, repetitive sequences that are dispersed throughout the genomeand account for 15% of dhuman DNA
3. Satellite DNA - repeat sequences arranged in tandem in a head to tail fashion

Question 7

What is transcription

Answer 7

RNA is synthesised according to a DNA template

RNA polymerase initiates transcrption from the non-coding anti-sense strand of the DNA.
RNA molecule is created in the 5’-3’ direction, identical base -pair sequence to the sense strand of DNA.