Unit 2 - Structure and Replication of DNA

Question 1

What 3 components make up a nucleotide

Answer 1

A base, deoxiribo sugar and a phosphate

Question 2

name the 4 types of bases found in a DNA molecule

Answer 2

Adenine, Thymine, Guanine and Cytosine

Question 3

what is the pairing rule of the bases

Answer 3

A - T
G - C

Question 4

what carbon in the deoxiribo sugar is bonded to the base

Answer 4

1’ / one prime

Question 5

which carbon bonds with a phosphate

Answer 5

5’ / 5 prime

Question 6

which end of the the carbon is left with the deoxiribo sugar

Answer 6

3’ / three prime

Question 7

what is a single strand of a DNA held together by

Answer 7

each strand of DNA is held together by a strong chemical bond between the sugar of one nucleotide and the phosphate of the next

Question 8

what are bases bonded by

Answer 8

bases are bound by weak hydrogen bonds

Question 9

what is the shape that DNA is wound into

Answer 9

a double stranded helix

Question 10

what name is given to the structure of the DNA molecule and why

Answer 10

it is called an Anti-Parallel structure, as each strand faces in opposite directions

Question 11

what does each 5’ DNA strand have at the end

Answer 11

a phosphate group

Question 12

what does each 3’ DNA strand have at the end

Answer 12

a dexoiribo sugar

Question 13

what enzyme is used to replicate DNA

Answer 13

prior to cell division a DNA polymerase is used to replicate the DNA

Question 14

what is needed to start replication of DNA

Answer 14

a primer is needed to start replication of DNA

Question 15

what is a primer

Answer 15

a primer is a short strand of nucleotides which binds to the 3’ end of the template strand of DNA

Question 16

how does DNA polymerase add DNA nucleotides

Answer 16

DNA polymerase adds DNA nucleotides by using complementary base pairings to the deoxyribose end of the new forming DNA strand

Question 17

why is the hydrogen bonds broken in a DNA nucleotide

Answer 17

when the DNA is unwound the hydrogen bonds between the bases break to form two new template strands

Question 18

what happens to the other strand untouched by DNA polymerase and why?

Answer 18

DNA polymerase can only add DNA nucleotides in one direction resulting in the leading strand being replicated continuously and a strand lagging replicated in fragments.

Question 19

what are the fragments of DNA joined by

Answer 19

fragments of DNA are joined by ligase

Question 20

what does PCR stand for

Answer 20

Polymerase Chain Reaction

Question 21

what is a primers function in relation to PCR

Answer 21

a primer is a short strand of nucleotides which are complementary to specific target sequences at the two ends of the region of DNA to be amplified.

Question 22

what amplifies the target region of DNA

Answer 22

a repeated cycle of heating and cooling will amplify the target region of DNA

Question 23

why is the DNA heated between 92 and 98°C in a PCR

Answer 23

DNA is heated between 92 and 98°C to separate the strands of the DNA

Question 24

why is the DNA cooled to between 50 and 65°C in a PCR

Answer 24

DNA is cooled between 50 and 65°C to allow the primers to bind to the target sequence

Question 25

why is the DNA heated to between 70 and 80°C in a PCR

Answer 25

DNA is heated between 70 and 80°C for the heatc tolerant DNA polymerase to replicate the region of DNA

Question 26

what are the practical applications of a PCR

Answer 26

PCR can amplify DNA to help solve crimes, settle paternity suits and diagnose genetic disorders.