DNA 1 - MT2 - Part 2

Question 1

How can a DNA molecule by copied?

Answer 1

By means of DNA polymerization reactions that are catalyzed by enzymes

Question 2

Semiconservative

Answer 2

Relating to or denoting replication of a nucleic acid in which one complete strand of each double helix is directly derived from the parent molecule
- mix of old and new strands

Question 3

Conservative

Answer 3

During replication, the 2 original strands of the DNA template stay together in a double helix and would produce a copy consumed of 2 new strands
- 2 different strands

Question 4

What is the name of the enzyme responsible for DNA replication?

Answer 4

DNA polymerase

Question 5

What can DNA polymerase do?

Answer 5

It can add nucleotides to the end of a pre-existing polynucleotide strand
- as long as another strand is there to serve as a template

Question 6

What are the 3 steps in replication?

Answer 6

1. Initiation
2. Elongation
3. Termination

Question 7

What is a source of mutations?

Answer 7

Errors in DNA replication

Question 8

What is the ultimate source of variation?

Answer 8

Mutation

Question 9

What 3 things can you add into a test tube to get a replication outside of a cell?

Answer 9

1. DNA polymerase
2. Free nucleotides
3. DNA

Question 10

Ethidium bromide

Answer 10

Is a flat fluorescent molecule that can slide between the stacked base pairs of DNA

Question 11

What happens when UV light is shone on ethidium bromide?

Answer 11

It absorbs the light and re-emits some of the energy as green light, telling you where the DNA is

Question 12

What happens when a current is applied to a solution containing DNA?

Answer 12

The DNA molecules will be drawn to the positive pole

- electrophoresis

Question 13

Why does DNA get drawn to the positive poles?

Answer 13

Because DNA has many negative charges on its backbone

Question 14

Charge density

Answer 14

The electric charge per unit area of a surface or per unit volume of a field or body

Question 15

What is separation speed through a gel based on? (3)

Answer 15

1. Shape
2. Charge density
3. Length size

• shape and charge density will have the same results so the size is the only thing that will differ

Question 16

What size of segments move faster?

Answer 16

Smaller ones

- compared to larger ones

Question 17

Electrophoresis

Answer 17

Separation of molecules in an electric field, according to size

Question 18

PCR

Answer 18

Polymerase chain reaction

Question 19

What does PCR do?

Answer 19

It amplifies specific DNA segments

Question 20

What does PCR depend upon?

Answer 20

DNA replication reactions

- which in turn depend on the phenomenon of specific base pairing

Question 21

Who invented PCR?

Answer 21

Kelly Mullis

Question 22

What year was PCR invented?

Answer 22

1984

Question 23

What kind of reaction is PCR?

Answer 23

Cyclic reaction

- each cycle takes a few mins

Question 24

What 5 things do you need for a PCR reaction?

Answer 24

1. DNA template
   - contains DNA molecule you want to amplify
2. Short DNA primers with sequences that flank the sequence you want to amplify
   - this gives it specificity
3. Free nucleotides
4. Taq polymerase
5. Thermal cycler

Question 25

What is an example of a DNA template?

Answer 25

Blood from a crime scene

Question 26

Taq polymerase

Answer 26

A DNA polymerase, from a heat resistant bacterium, that can be heated without being destroyed

Question 27

Thermal cycler

Answer 27

A small unit for your reaction tubes that can heat up quickly and cool down quickly

Question 28

What does DNA replication need to begin the new strand?

Answer 28

A primer

- the process cant just begin anywhere

Question 29

What happens in the PCR cycle? (4)

Answer 29

1. The thermal cycler heats up and the DNA is denatured to 2 separate polynucleotide strands
2. The thermal cycler is cooled, the single stranded primers anneal to their complementary sequence on the target gene
3. The taq polymerase extends the primers, making a new DNA strand that is complementary to one of the target strands
4. The thermal cycler is heated again, the DNA double helixes melt and a new cycle begins

Question 30

What happens to the amount of DNA after every cycle?

Answer 30

It gets doubled