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Higher Biology > 1.2 Replication of DNA > Flashcards

1.2 Replication of DNA Flashcards

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1
Q

Why is DNA replicated?

A
  • daughter cells have the same number of chromosomes and so that they have the same genes.
  • it happens before mitosis which is needed for growth and repair
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2
Q

What is the term to describe how DNA replicates itself?

A

semi-conservative replication

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3
Q

What are the 3 stages of DNA replication?

A
  1. -DNA unwinds
    - hydrogen bonds between the bases break
    - to form two template strands
  2. leading strand
    - primer binds at the 3’ end of the strand
    - DNA polymerase adds nucleotides to the 3’ end of the primer continuously

lagging strand

  • many primers attach along the strand
  • as DNA polymerase can only add nucleotides to the 3’ end of the primer
  • DNA polymerase adds nucleotides onto the 3’ end of the primers creating fragments
  • these fragments joined together
  • discontinuous process
  1. -The two new strands form a double helix.
    - The new strands are identical to the original strands
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4
Q

What is the first stage of DNA replication?

A
  1. -DNA unwinds
    - hydrogen bonds between the bases break
    - to form two template strands
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5
Q

What is the second stage of DNA replication?

A
  1. leading strand
    - primer binds at the 3’ end of the strand
    - DNA polymerase adds nucleotides to the 3’ end of the primer continuously

lagging strand

  • many primers attach along the strand
  • as DNA polymerase can only add nucleotides to the 3’ end of the primer
  • DNA polymerase adds nucleotides onto the 3’ end of the primers creating fragments
  • these fragments joined together
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6
Q

What is the third stage of DNA replication?

A
  1. -The two new strands form a double helix.

- The new strands are identical to the original strands

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7
Q

What does the enzyme DNA polymerase do?

A

DNA polymerase adds DNA nucleotides, using complementary base pairing, to the 3’ end of the new DNA strand which is forming or primer.

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8
Q

What end of the growing strand (or primer) can DNA polymerase add nucleotides to?

A

the 3’ end

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9
Q

What is the process of replicating the leading strand of DNA?

A
  1. leading strand
    - primer binds at the 3’ end of the strand
    - DNA polymerase adds nucleotides to the 3’ end of the primer continuously
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10
Q

What is a primer and what is its role?

A
  • short strand of nucleotides which binds to the 3’ end of the template DNA strand
  • allowing DNA polymerase to add DNA nucleotides.
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11
Q

What is the process of replicating the lagging strand of DNA?

A

lagging strand

  • many primers attach along the strand
  • as DNA polymerase can only add nucleotides to the 3’ end of the primer
  • DNA polymerase adds nucleotides onto the 3’ end of the primers creating fragments
  • these fragments joined together
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12
Q

What are the requirements for DNA replication?

A

the nucleus must contain:

  • DNA (to act as a template)
  • Primers
  • A supply of the 4 types of nucleotide
  • DNA polymerase and ligase enzymes
  • A supply of energy (ATP)
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13
Q

What is the purpose of PCR?

A

amplification of DNA in Vitro using complementary primers for specific target sequences

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14
Q

What machine does PCR take place in?

A

thermocycler

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15
Q

What is the first stage of PCR?

A

The DNA is heated to approximately 92-98C for a few seconds. This causes the DNA to denature and the strands to separate

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16
Q

What is the second stage of PCR?

A

The DNA is cooled to approximately 50-65C for a few seconds. This makes short primers bond to the separated DNA strands.

17
Q

What is the third stage of PCR?

A

The DNA is heated again to between 70C and 80C for a few minutes. This allows heat tolerant DNA polymerase to replicate the DNA
repeated cycles of heating and cooling amplify the target region of DNA

18
Q

What is the process of PCR?

A
  1. DNA is heated to 92-98C
    - to break hydrogen bonds between bases, separating the strands
  2. DNA is cooled to 50-65C
    - allows primers to bond to target sequences
  3. DNA is heated to 70-80C
    - allow heat tolerant DNA polymerase to add nucleotides to the 3’ end of the primer
    - and replicates the region of DNA
  4. repeated cycles of heating and cooling amplify the target region of DNA
19
Q

What happens with each PCR cycle?

A

the number of copies of the DNA doubles

20
Q

What are the requirements for PCR?

A
  • DNA sequence-template
  • heat tolerant DNA polymerase-so it doesn’t denature
  • primers
  • supply of nucleotides of the 4 different bases
  • thermocycler
21
Q

Name 3 uses of PCR

A
  1. solve crimes
  2. Disease detection
  3. paternity suits
22
Q

What is the enzyme used to copy DNA?

A

DNA polymerase

23
Q

Why is one strand called the leading strand and one called the lagging strand?

A
  • delay in the replication of the lagging strand compared to the leading strand
  • lagging strand has to be synthesised in fragments
  • fragments are then joined together by DNA ligase.
24
Q

what is the role of DNA ligase?

A

To join fragments of DNA together

25
Q

What temperatures are the stages of PCR carried out at?

A
  1. 92-98*C
  2. 50-65*C
  3. 70-80*C
26
Q

why is heat tolerated DNA polymerase required for PCR?

A

to withstand repeated cycles of heating and cooling so the enzyme doesn’t get denatured

27
Q

What is a primer in PCR?

A

short strands of nucleotides

  • which are complementary to specific target sequences
  • at two ends of the region if DNA to be amplified

Higher Biology (25 decks)

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