Human Cells Unit 1 KA2

Question 1

What are DNA Nucleotides made up of? (3)

Answer 1

1) Deoxyribose sugar
2) Phosphate
3) Base

Question 2

What four bases are found in a DNA Nucleotide?

Answer 2

1) Adenine
2) Thymine
3) Guanine
4) Cytosine

Question 3

What are the two Complementary base pairs?

Answer 3

1) Adenine + Thymine
2) Guanine + Cytosine

Question 4

What does DNA consist of?

Answer 4

DNA consists of repeating units called nucleotides

Question 5

What is joined to the Carbon 3 end?

Answer 5

Deoxyribose is joined at the Carbon 3 end in each chain

Question 6

What is joined to the Carbon 5 end?

Answer 6

The Phosphate group is joined at the Carbon 5 end in each chain

Question 7

What is the structure of DNA?

Answer 7

Two strands of nucleotides running in antiparallel directions, held together by weak hydrogen bonds, forming a double helix

Question 8

What must happen before cell division occurs?

Answer 8

Before cell division occurs, the DNA in the nucleus must be replicated

Question 9

Which Enzyme replicates DNA?

Answer 9

DNA Polymerase replicates DNA

Question 10

What are the four stages of DNA Replication?

Answer 10

1) Double helix unwinds
2) Hydrogen bonds between base pairs break forming two template strands
3) Template strands become stabilised and expose bases at Y shaped replication fork
4) One strand of the replication fork is a template for the Leading strand, the other for the Lagging strand

Question 11

Which template strand forms the Leading strand?

Answer 11

The template strand with the 3’ end is continuous and forms the Leading strand

Question 12

What must be present to create an existing chain for DNA Polymerase to work on?

Answer 12

A DNA Primer must be present for DNA Polymerase to work on

Question 13

Which end of the Primer are DNA Nucleotides added to?

Answer 13

DNA Nucleotides are added to the 3’ end of the Primer

Question 14

Which template strand forms the Lagging strand?

Answer 14

The template strand with the 5’ end is discontinuous, replicating in fragments which form the Laggng strand

Question 15

Which Enzyme joins fragments together to create the Lagging strand?

Answer 15

Ligase joins fragments together to create the Lagging strand

Question 16

What are the requirements for DNA Replication? (5)

Answer 16

1) DNA (acts as a template)
2) Primers (creates existing chain for DNA polymerase)
3) DNA Nucleotides (A+T, G+C)
4) Enzymes (DNA Polymerase, Ligase)
5) ATP (energy)

Question 17

Why is DNA Replication so important?

Answer 17

DNA Replication is important to ensure that, before a cell divides, theres the correct quantity of DNA to fill the nuclei of both new cells

Question 18

What could happen if theres an error in the process of DNA Replication?

Answer 18

If an error occurs in the process of DNA Replication, a non-functional protein could be produced which may have a harmful effect. (See KA 4)

Question 19

What is the Polymerase Chain Reaction (PCR)?

Answer 19

PCR is a method used to amplify DNA

Question 20

What happens in PCR Stage 1/3?

Answer 20

In Stage 1 of PCR -
DNA is heated to between 92-98C
to seperate the strands

Question 21

What happens in PCR Stage 2/3?

Answer 21

In Stage 2 of PCR -
DNA is cooled to between 50-65C
to allow primers to bind

Question 22

What happens in PCR Stage 3/3?

Answer 22

In Stage 3 of PCR -
DNA is heated to between 70-80C
so heat tolerant DNA polymerase can replicate the DNA

Question 23

What are the practical applications of PCR?
(3)

Answer 23

1) Amplify DNA to solve crimes
2) Settle paternity disputes
3) Diagnose genetic disorders