DNA Structure, Function and Replication

Question 1

How is DNA found in a prokaryote?

Answer 1

No Nuclear membrane, in a single chromosome (sometime circular)

Question 2

How is DNA found in a Eukaryote?

Answer 2

Nucleus, bound to proteins (histones) to form chromatin, (SOME in mitochondria)

Question 3

What are the 2 functions of DNA?

Answer 3

1) Template and regulator for transcription/Prot synth

2) Genetic material, structural basis of heredity and GD

Question 4

What was unusual of how Mendel observed DNA?

Answer 4

Granular, traits passed on in a quantitative process

Question 5

What is the essential nature of heritable material?

Answer 5

That it has to be able to be copied

Question 6

What does it mean if strands are anti-parallel?

Answer 6

Strands run in opposite directions but still run in 5’ to 3’ (Forming phosphodiester bonds)

Question 7

How long and how are chromosomes organised in Eukaryotic DNA?

Answer 7

1) 2m linear

2) Complex packaging

Question 8

Why is heterochromatin dark?

Answer 8

Stains darker, as non condensed, and DNA is very densely packed

Question 9

Why is DNA described as being Semi-Conservative?

Answer 9

Composed of a new and template strand

Question 10

Function of Topoisomerase?

Answer 10

Used to untwist DNA from supercoil, so easier to access

Question 11

Function of Primase?

Answer 11

Production of Primers

Question 12

Function of Ligase?

Answer 12

Join DNA fragments (okazaki) together

Question 13

Function of DNA Polymerase?

Other than Assemble DH

Answer 13

Can edit strand, remove mistake and start assembly again.

Question 14

Role of Primers?

Answer 14

Small section of RNA which anneals to DNA via HB to initiate replication

Question 15

How can DNA be damaged? (3)

Answer 15

1) Chemical e.g. Benzopyrene
2) Radiation (X-ray/Ionising–>Break in PSB)
3) Spontaneous insertion of incorrect base

Question 16

2 forms of mutation?

Answer 16

1) DNA Damage

2) DNA repair (Mismatch repair, Base/nuc excision)