Revision

Question 1

nucleotide

Answer 1

base
sugar
phosphate

Question 2

nucleoside

Answer 2

base
sugar
no phosphate

Question 3

hybvridisation

Answer 3

in mixture of DNA with diffsequences

complementary strands will find each other

Question 4

reannealing

Answer 4

lower temp
increase salt conc
melted strands reanneal to double helix

Question 5

E coli genome

Answer 5

4.7x10(power 6) base pairs in single circular double stranded molecule
genome = 1.4mm
DNA tightly packaged

Question 6

human genome

Answer 6

haploid - 3x10(power9) bp of DNA
divided into chromosomes - linear double-helical DNA molecule 200x10(power 6)
DNA condenses into discrete chromosomes so you can see them

Question 7

how many base pairs per helical turn in DNA

Answer 7

10

Question 8

what is the width of the double helix

Answer 8

2nm

Question 9

what wraps around the octamer of histones

Answer 9

DNA

in L handed superhelix

Question 10

how many genes in the human genome

Answer 10

23000

Question 11

RNA polymerase III

Answer 11

transcribes tRNA and 5sRNA genes

Question 12

length of DNA in 1 nucleus

Answer 12

> 1m

Question 13

when does chiasma formation occur

Answer 13

meiosis

Question 14

proof reading DNA

Answer 14

phosphodiester bonds are hydrolysed before replacement of incorrect nucleotides with the correct nucleotides
errors occur with frequency of 1 change per 10to the 9 bp

Question 15

what is at the unwound end of the template strand for the leading strand

Answer 15

3’

Question 16

what is metylation needed for in the formation of the CAP structure

Answer 16

modification of the purine ring

Question 17

endocrinopathies that thalassemia is associated with

Answer 17

DM

thyroid disorders

Question 18

affect of thalassemia on skin colour

Answer 18

darkening

due to melanin overproduction and overstimulation