U1 KA2- Structure Of DNA

Question 1

What form is genetic code?

Answer 1

The base sequence of DNA

Question 2

What is stored by genetic code?

Answer 2

Instructions for making proteins

Question 3

Name all of the components in a nucleotide

Answer 3

• A phosphate
• A deoxyribose sugar
• A base

Question 4

What are the 4 DNA bases and their pairs?

Answer 4

• Adenine’s complementary base pairs is thymine
• Cytosins’s complimentary base pair is guanine

Question 5

What forms the sugar phosphate backbone of DNA?

Answer 5

The phosphate of one nucleotide is joined to the deoxyribose sugar of the
next nucleotide

Question 6

What shape is a DNA molecule?

Answer 6

A double helix

Question 7

Describe the strands of a double helix

Answer 7

Anti parallel (they run in the opposite direction from each other)

Question 8

What are the two DNA strands held together by?

Answer 8

Weak hydrogen bonds between complementary bases

Question 9

What are chromosomes composed of?

Answer 9

Tightly coiled DNA

Question 10

What is at the 3’ end of DNA?

Answer 10

A deoxyribose sugar

Question 11

What is at the 5’ end of DNA?

Answer 11

A phosphate

Question 12

What are the requirements for DNA replication?

Answer 12

-DNA template
-free nucleotides
-ATP
-DNA primers
-enzymes

Question 13

What is the first step of DNA replication?

Answer 13

The DNA helix is unwound as hydrogen bonds between bases break to form two template strands

Question 14

What is a primer?

Answer 14

A short strand of nucleotides

Question 15

In DNA replication, how is the leading strand synthesised and how is the lagging strand synthesised?

Answer 15

The leading strand is replicated continuously while the lagging strand is replicated in fragments

Question 16

State the two enzymes used in DNA replication

Answer 16

DNA polymerase, and ligase

Question 17

State the role of ligase in DNA replication

Answer 17

To join together the fragments of DNA on the lagging strand

Question 18

In what direction does DNA polymerase add DNA nucleotides?

Answer 18

3’ to 5’

Question 19

State the role of DNA polymerase in DNA replication

Answer 19

Adds nucleotides and proofreads

Question 20

Where does PCR occur?

Answer 20

In vitro

Question 21

What is PCR?

Answer 21

A technique used to create many copies of a piece of DNA

Question 22

PCR ______ a piece of DNA

Answer 22

Amplifies

Question 23

What are the requirements for a PCR?

Answer 23

-DNA template
-Complementary primaries to target DNA sequence
-Free nucleotides
-Buffer solution to maintain PH
-Heat tolerant polymerase (Taq polymerase)

Question 24

What allows PCR to be very specific to a particular sequence of DNA?

Answer 24

The primer used is selected to be complementary to a specific target sequence

Question 25

State some practical applications of PCR

Answer 25

-Forensics (amplifying samples from crime scene)
-Medical (diagnosis of genetic disorders and diseases)
-Paternity testing