Nucleic Acids

Question 1

What is the structure of a DNA nucleotide

Answer 1

It is made of a five carbon pentose sugar,
A nitrogen containing organic base and a phosphate group

Question 2

What pentose sugar is in DNA

Answer 2

Deoxyribose

Question 3

What are purine bases

Answer 3

Contain two rings,
Adenine and Guanine

Question 4

What are Pyrimidine bases

Answer 4

Have only one ring,
Cytosine and Thymine

Question 5

How is the a DNA nucleotide formed

Answer 5

The pentose sugar attaches to the phosphoric acid at carbon 5,
The pentose sugar attaches to the organic base at carbon 1,
The nucleotides are then strung together to form a nucleic acids, the back bone is made of alternating sugar and phosphate groups,
The bases project out at the side

Question 6

What did Watson and Crick develop

Answer 6

They used X Ray diffraction techniques, developed by Franklin, to work out the structure of DNA

Question 7

Which pentose sugar is in RNA

Answer 7

Ribose

Question 8

What purine organic bases are in RNA

Answer 8

A and G

Question 9

What Pyrimidine organic bases are in RNA

Answer 9

C and U

Question 10

How many strands are in RNA

Answer 10

It is single stranded

Question 11

What are some adaptations of DNA to its function

Answer 11

1. It is stable, held together by strong covalent bonds
2. It can copy its self accurately because of the complementary pairing of the bases
3. It is capable of folding so lots of information can be stored in a small volume
4. The information can be easily copied
5. The hydrogen bonds are easily broken allowing replication and protein synthesis

Question 12

What are some adaptations of RNA to its function

Answer 12

1. It is single stranded so that mRNA can carry a copy of the DNA code with unpaired bases exposed
2. It is smaller than the DNA molecule so that it can travel out of the nucleus and move around the cell
3. It forms base pairs with the correct tRNA molecule to control the sequence of amino acids in a polypeptide chain

Question 13

What does DNA Helicase do

Answer 13

It separates the two DNA strands using energy from ATP

Question 14

What do DNA binding proteins do

Answer 14

They keep the strands separate during replication

Question 15

What does DNA polymerase do

Answer 15

Catalyses the polymerisation to from the polynucleotide chain in the 5 to 3 direction, allowing the strand to be replicated continuously

Question 16

What does DNA ligase do

Answer 16

Joins pieces of the polynucleotide chain together

Question 17

Describe semi-conservative replication

Answer 17

1. DNA double helix unwinds as the hydrogen bonds between the organic bases are broken by helicase
2. This exposes the organic bases which are kept apart by DNA binding proteins
3. Free nucleotides with the correct complementary bases slot into place opposite the exposed bases on each strand
4. A and T always join together and G and C
5. Hydrogen bonds are formed between the bases, joining the two strands
6. DNA polymerase joins the nucleotides together continuously in the chain running in the 5 to 3 direction
7. In the other direction DNA polymerase joins nucleotides together in short sections that are linked by ligase
8. A new strand of DNA has then been formed against each of the old strands

Question 18

What is the structure of ATP

Answer 18

Adenine, Ribose and 3 phosphate groups

Question 19

What is ATP used for

Answer 19

It transfers energy within cells by undergoing hydrolysis, which releases energy that can be used by the cell, This is done by breaking one of the phosphate bonds in ATP, which releases energy that can be used by the cell

Question 20

What is an ion

Answer 20

A charge particle