DNA

Question 1

name the pentose sugar in DNA

Answer 1

DNA: deoxyribose

Question 2

describe the structure of DNA

Answer 2

• molecule twists to form double helix of 2 deoxyribose polynucleotide strands (therefore 2 sugar phosphate backbones)
• H-bonds form between complementary base pairs (AT and GC) on strands that run antiparallel

Question 3

name the complementary base pairs in DNA

Answer 3

• 2 H-bonds between adenine and thymine (AT)
• 3 H-bonds between guanine and cytosine (GC)

Question 4

describe and explain how DNA can be extracted

Answer 4

1. mash / grind sample to break down tissue / cell walls
2. add detergent to rupture cell surface membranes
3. add salt to break H-bonds between DNA and water molecules
4. add protease enzyme to uncoil DNA and break down its associated proteins known as histones
5. use filter paper to filter the mixture into another beaker to remove unwanted parts / fragments
6. add ice cold ethanol to test tube to precipitate the DNA
7. collect DNA by spooling