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Higher Biology 2022 > 1.2 Replication of DNA > Flashcards

1.2 Replication of DNA Flashcards

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1
Q

What is ‘DNA Replication’?

A

Process by which the Cell makes an identical copy of their DNA at the beginning of each cell division

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2
Q

Why is DNA replication important?

A

Ensures each daughter cell has an IDENTICAL copy of genetic material inherited from parent cell and NO GENETIC INFORMATION IS LOST

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3
Q

What are the key requirements for DNA Replication?

A
  • DNA Polymerase
  • Template DNA strand
  • Primer
  • Ligase
  • ATP
  • Free DNA nucleotides
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4
Q

What is the function of DNA Polymerase in replication

A

Adds free complementary nucleotides to the parent strand starting at 3’ end and forms strong chemical bonds between phosphate and sugars of DNA strand.

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5
Q

Why is an original DNA strand needed?

A

To provide the template to be copied

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6
Q

What is a primer?

A

A short sequence of DNA nucleotides that initiates replication and allows DNA polymerase to start adding nucleotides

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7
Q

What is Ligase used for in DNA replication?

A

Joins together the DNA fragments

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8
Q

Why is ATP needed in DNA replication?

A

To provide energy to break the bonds between bases when DNA is being unwound

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9
Q

State the steps in DNA replication

A
  1. DNA is unwound, hydrogen bonds break between bases and a replication fork is formed
  2. A primer is added to a complementary sequence at the 3’ end
  3. DNA polymerase comes along and starts adding free complementary nucleotides to the 3’ end, and DNA Polymerase forms a strong sugar phosphate bond between nucleotides
  4. Replication is continuous on the leading strand but discontinuous on the lagging strand due to the antiparallel nature of DNA
  5. DNA fragments are joined together by Ligase and hydrogen bonds form between bases
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10
Q

What are the two strands in DNA replication?

A

Leading strand and Lagging Strand

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11
Q

Describe the replication of the lagging strand

A

Discontinuous due to antiparallel nature of DNA
DNA fragments are formed
Fragments must be glued together by Ligase

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12
Q

What side can new nucleotides be added to?

A

3’

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13
Q

What glues DNA fragments together?

A

Ligase

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14
Q

What does PCR stand for?

A

Polymerase Chain Reaction

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15
Q

What is PCR?

A

PCR is the amplification of DNA sequences in vitro by thermocycling

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16
Q

What is thermocycling?

A

Repeated heating and cooling cycles

17
Q

What are the three temperatures needed for PCR?

A

94 degrees
55 degrees
72 degrees

18
Q

Why must DNA be heated to 94 degrees?

A

To denature the DNA, separating the strands and breaking the hydrogen bonds

19
Q

What happens when the DNA is cooled to 55 degrees?

A

Allows primers to anneal to target sequences in DNA

20
Q

At 72 degrees what is added?

A

Taq Polymerase (Heat tolerant Polymerase)

21
Q

Why is Taq (Heat tolerant) Polymerase used in PCR?

A

Because it is able to withstand high temperatures (like 72 degrees) without being denatured

22
Q

Why are two different primers required in PCR?

A
  • Two strands of DNA

- Two specific complementary sequences that must be found

23
Q

How is DNA separated?

A

Using gel electrophoresis

24
Q

Give an example of a practical use of PCR

A

Paternity Testing
Forensics
Evolutionary Study

25
Q

What is a positive control for PCR?

A

Doing PCR with a known sample of DNA, expected result is known

26
Q

What does a PCR allow the scientist to prove?

A

PCR equipment is not contaminated

27
Q

What is a negative control for PCR?

A

Doing PCR with a key factor missing (such as removal of DNA Polymerase) to prove no contamination

28
Q

If the scientist did X cycles of PCR, how many copies of DNA would they expect to find

A

2^x

29
Q

If a scientist did 5 cycles of PCR, how many copies of the DNA would they have

A

32

30
Q

Describe the direction of replication on the lagging strand

A

3’ to 5’

Higher Biology 2022 (24 decks)

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