3.8 Nucleic Acids

Question 1

What are the components of a nucleotide?

Answer 1

• a pentose sugar
• a phosphate group
• an organic nitrogenous base

Question 2

Which bases are purines

Answer 2

Adenine

Guanine

Question 3

Which bases are pyrimidine?

Answer 3

Thymine

Cytosine

Question 4

What is a purine base’s structure?

Answer 4

A double ring structure

Question 5

What is a pyrimidine base’s structure?

Answer 5

Single ring structure

Question 6

How many hydrogen bonds are there between adenine and thymine?

Answer 6

Two hydrogen bonds

Question 7

How many hydrogen bonds are there between guanine and cytosine?

Answer 7

Three hydrogen bonds

Question 8

What is the structure of DNA?

Answer 8

Double helix structure with two polynucleotides running in opposite directions to each other

Question 9

What are the three forms of RNA?

Answer 9

tRNA, mRNA, rRNA

Question 10

What is the difference between DNA and RNA?

Answer 10

DNA is double helix
DNA contains thymine, RNA contains uracil
DNA contains deoxyribose as a sugar, RNA contain ribose as a sugar

Question 11

Why do C-A and T-G base pairings not occur

Answer 11

Because of their size - the sizes would be uneven and not parallel

Question 12

How do you extract DNA from a plant cell?

Answer 12

1. Grind tissue (to break down cell walls)
2. Mix with detergent (to break cell walls)
3. Add salt (to break hydrogen bonds between DNA polynucleotides)
4. Add protease enzyme (to break down proteins surrounding DNA)
5. Add alcohol (to precipitate DNA out of solution)
6. Remove DNA (which can be seen as white strands below alcohol layer)