Topic 7

Question 1

Pyrimidines

Answer 1

CT

Question 2

Purines

Answer 2

AG

Question 3

What does C pair with

Answer 3

G

Question 4

What does A pair with

Answer 4

T

Question 5

A+G=

Answer 5

T+C

Question 6

A=
G=

Answer 6

T
C

Question 7

What does every full twist of a dna have

Answer 7

10 base pairs (5 paired with 5)

Question 8

How many h bonds does gc have

Answer 8

3

Question 9

What is the 3’ end

Answer 9

The one with the oh

Question 10

What carbon of the sugar is the phosphate bonded to

The nucleotide

Answer 10

5’ and 3’ carbons
1’ carbon

Question 11

What is cleaved off to make the rest of the replicated dna strand

Answer 11

Pyrophosphate, give NRG to drive the rxn

Question 12

New stuff is added to which end

Answer 12

3’

Synthesis in 5-3

Question 13

What does helicase do

Answer 13

Break h bonds between nucleotides In The dna strand

Question 14

What do ss dna binding protiens do

Answer 14

Stabilize the unwound dna from helicase

Question 15

What does gyrase do

Answer 15

Type of topoisomerase
Relaxes the dna strands and stops them from coiling up and then rejoins the strands. It’s behind the replication fork

Question 16

What does DNA pol. III do

Answer 16

Catalyzed dna synthesis. Extends existing dna strand but cannot start a new one

5-3

Question 17

Leading stand and laggin strand

Answer 17

Leading strand is the strand synthesized from the top 5-3 template strand

The laggin strand is the strand made from the bottom 3-5 template

Question 18

Dna pol 1

Answer 18

Removes the rna primer and fills gap left behind

Question 19

Dna ligase

Answer 19

Connects the Okazaki fragments

Question 20

Rna polymerase

Answer 20

Makes the rna primer which is the starting pint for dna pol

Question 21

Dna ligase makes what type of bond

Answer 21

Phosphodiester bond

Question 22

What is PCr (polymerase chain rxn)

Answer 22

A way to amplify a piece of dna (double helix)

Make a billion of the same dna

Question 23

What does you need for PCr

Answer 23

1. Template dna: Extract all dna (genomic dna) and analyze small portion of a gene in the dna
2. Design dna primers that have a free oh group that bind to the region of the gene you’re looking at
   Need a forwards primer (complementary to bottom template strand) need reverse primer( reverse complement to top template strand)
3. Need dntps (agtc)
4. Tac polymerase: type of dna pol to synthesis the dna, best polymerase for PCr

Question 24

What happens in PCr

Answer 24

1. Heating at 95 degrees, denatures h bond and separates the two strands
2. Cooling and 55-66 degrees. Anneals the primers to their location on the template dna
   3.heat to 72 degrees, synthesis, taq pol adds to 3’ end of Top and bottom primers
   All these step repeated over and over to amplify and make billion copies

Question 25

What determines the corrects annealing temp in PCr

Answer 25

The melting temp of the primer

The melting temp is the temp where 50% of primers are are bound to dna and 50% aren’t

Question 26

What determines the melting temp of the primer

Answer 26

The amount of gc

More gc higher melting temp

Length of the primer, longer higher melting temp

Question 27

The aneealing temp should be ______ than the melting temp

Answer 27

Lower

To encourage binding

Question 28

What is gel electrophoresis

Answer 28

A method to separate the dna molecules based on their size. Use el tric field to move the dna through the gel

To check if PCr amplified a region of the the size we wanted

Question 29

Why is gel electrophoresis negative and positive charge

Answer 29

Since dna is negative charge, they will travel towards postive charge at the bottom of the gel.

Negative charge is at the wells

Question 30

Why do we stain the dna in gel electrophoresis

Answer 30

To see the dna in the gel, dna is colourless so we add colour the fluorescence under uv

Question 31

What is the molecular ladder

Answer 31

Had dna prices of known sizes that determin size of the PCr dna

Question 32

Why do we use taq pol in PCr

Answer 32

Active at high temps and remains active