Lecture 1

Question 1

Who founded DNA?

Answer 1

Friedrich Miescher

Question 2

What must genetic information be?

Answer 2

Stable for storage but available for direct cellular processes

Question 3

Describe genetic material

Answer 3

•	Be stable over time
o	DNA is stable lasting many years
•	Be able to be replicated
o	Semiconservative replication
•	Be able to control expression of traits
•	Be able to change in a controlled way

Question 4

Describe the structure of DNA

Answer 4

DNA is a double helix – phosphate groups lie on the outside, helix of diameter of 20A, each strand is a linear polumer made of up of repeating units. Each DNA strand has directionality.
Each DNA strand has 5’  3’ directionality
DNA strands are antiparallel and are held together by hydrogen bonds between complementary base pairs
• A and T – 2 H bonds
• C and G – 3 H bonds
• Large base (purine) with small base (pyrimidine)
Nucleotide = sugar + base + phosphate
Sugar + base = nucleoside

Question 5

Deoxyribose + each base =

Answer 5

deoxyadenosine, deoxyguanosine, deoxycytidine, deoxythymidine

Question 6

Define genome

Answer 6

All the DNA in the nucleus of a cell or of an organelle

Question 7

what is the size of the haploid human nuclear genome?

Answer 7

3.0 x 109 bp

Question 8

What is the size of DNA in the human cell

Answer 8

6 x 109 base pairs DNA and 2 metres long, nucleus 10 micrometres diameter

Question 9

What is dsDNA packaged in

Answer 9

chromosome through interactions with specialised proteins

Question 10

Describe DNA and histones

Answer 10

DNA wraps twice around 8 core histone proteins to form nucleosomes
• Histone H1 brings the nucleosomes together to form a chromatin fibre
• Chromatin is further condensed by scaffold proteins
• Interphase chromosomes are organised in the nucleus

Question 11

Describe Euchromatin

Answer 11

o less compact DNA form

o contains genes that are frequently expressed

Question 12

Describe Heterochromatin

Answer 12

more compact and contains DNA that isn’t transcribed

Question 13

What is the nucleoli?

Answer 13

regions where chromosomes carrying rRNA cluster, rRNAs are synthesised and ribosomes are assembled

Question 14

Describe chromosomes

Answer 14

organise themselves into discrete patches – chromosome territories, active genes, which are found in the euchromatric region of the chromosome