Unit 6a - The Molecular Basis of Inheritance

Question 1

Chargaff’s Rules

Answer 1

dna composition varies between species

Question 2

Base pair ratios

Answer 2

a% = t% + c% = g%

Question 3

Purines

Answer 3

double ring; A + G , paired with pyrimidine

Question 4

Pyrimidine

Answer 4

single ring: T + C, paired with purine

Question 5

Hydrogen bond

Answer 5

between base pairs of the two strands that hold the molecule together

Question 6

The bond between A + T

Answer 6

double bond

Question 7

The bond between C + G

Answer 7

triple bond

Question 8

Prokaryotic DNA

Answer 8

double stranded
circular
one chromosome
in cytoplasm
no histones
super-coiled DNA

Question 9

Eukaryotic DNA

Answer 9

double stranded
linear
1+ chromosome (usually)
DNA wrapped around histones
forms chromatin

Question 10

Antiparallel

Answer 10

one strand 5’ to 3’ , the other is 3’ to 5’

Question 11

Define Semi-conservative

Answer 11

half of the DNA is original ; half is newly synthesized

Question 12

Function of Helicase

Answer 12

unzip and unwind DNA

Question 13

Function of Polymerase

Answer 13

adds nucleotide to the new DNA strands

Question 14

Function of Primase

Answer 14

adds RNA primer

Question 15

RNA primer

Answer 15

provides a binding site for the DNA polymerase

Question 16

Function of Ligase

Answer 16

joins Okazaki fragments

Question 17

Okazaki Fragments

Answer 17

allow DNA polymerase to synthesize the lagging strand in segments,

Question 18

Topoisomerase

Answer 18

prevents supercoiling of DNA at replication fork

Question 19

Nucleotides are added to the …

Answer 19

3’ end ONLY

Question 20

Replication happens in the

Answer 20

5’ –> 3’ direction

Question 21

1st Major Step of DNA Replication

Answer 21

helicase unwinds at origins of replication

Question 22

2nd Major Step of DNA Replication

Answer 22

initiation proteins separate 2 strands –> form replication fork

Question 23

3rd Major Step of DNA Replication

Answer 23

primase puts down RNA primer

Question 24

4th Major Step of DNA Replication

Answer 24

dna polymerase III adds complimentary bases to leading strand

Question 25

5th Major Step of DNA Replication

Answer 25

Lagging strand grows by the addition of Okazaki fragments

Question 26

6th Major Step of DNA Replication

Answer 26

dna polymerase I replaces RNA primers with DNA

Question 27

7th Major Step of DNA Replication

Answer 27

dna ligase seals fragments together

Question 28

Telomeres

Answer 28

repeated units of short nucleotide sequences (TTAGGG) at the ends of DNA
telomerase is its enzyme