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A Level Bio Extra Cards > 2.2: DNA replication > Flashcards

2.2: DNA replication Flashcards

1
Q

The discovery of DNA’s structure by Watson and Crick provided evidence that what was key to DNA’s ability to replicate?

A

The discovery of DNA’s structure by Watson and Crick provided evidence that complementary base pairing was key to DNA’s ability to replicate

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2
Q

The discovery of DNA’s structure by Watson and Crick provided evidence that complementary base pairing was key to DNA’s ability to replicate.
What did scientists propose?

A

Scientists proposed that DNA ‘unzipped,’ as hydrogen bonds between base pairs were broken

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3
Q

The discovery of DNA’s structure by Watson and Crick provided evidence that complementary base pairing was key to DNA’s ability to replicate.
Scientists proposed that DNA ‘unzipped,’ as hydrogen bonds between base pairs were broken.
New polynucleotide strands could then be synthesised using what as a template?

A

New polynucleotide strands could then be synthesised using the originals as a template

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4
Q

The discovery of DNA’s structure by Watson and Crick provided evidence that complementary base pairing was key to DNA’s ability to replicate.
Scientists proposed that DNA ‘unzipped,’ as hydrogen bonds between base pairs were broken.
New polynucleotide strands could then be synthesised using the originals as a template.
Several hypotheses were then proposed as what?

A

Several hypotheses were then proposed as to the specific mechanism by which new strands are created

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5
Q

Why does DNA need to replicate?

What are reasons for DNA replication?

A

Reasons for DNA replication are:

  1. Cell division
  2. Reproduction
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6
Q

Why does DNA need to replicate?

Reasons for DNA replication are cell division - New cells need new DNA for what, and reproduction?

A

Reasons for DNA replication are:

  1. Cell division - New cells need new DNA for growth and tissue repair
  2. Reproduction
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7
Q

Why does DNA need to replicate?
Reasons for DNA replication are cell division - New cells need new DNA for growth and tissue repair, and reproduction - What require DNA to do what?

A

Reasons for DNA replication are:

  1. Cell division - New cells need new DNA for growth and tissue repair
  2. Reproduction - Gametes require DNA to pass on genetic information
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8
Q

Enzymes in DNA replication:

What does DNA helicase do?

A

DNA helicase:

  1. Breaks hydrogen bonds
  2. Unwinds the molecule
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9
Q

Enzymes in DNA replication:

What does DNA polymerase do?

A

DNA polymerase forms the phosphodiester bonds between nucleotides

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10
Q

Before a nucleus divides, what must happen?

A

Before a nucleus divides, its DNA must be replicated (copied)

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11
Q

Before a nucleus divides, its DNA must be replicated (copied).
This is to ensure what?

A

This is to ensure that all the daughter cells have the genetic information to produce the:
1. Enzymes
2. Other proteins
that they need

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12
Q

For semi-conservative replication to take place, there are how many requirements?

A

For semi-conservative replication to take place, there are 4 requirements:

  1. The 4 types of nucleotide, each with their bases of A, T, C or G, must be present
  2. Both strands of the DNA molecule act as a template for the attachment of these nucleotides
  3. The enzyme DNA polymerase
  4. A source of chemical energy is required to drive the process
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13
Q

The process of semi-conservative replication:

The enzyme what breaks the hydrogen bonds linking the base pairs of DNA?

A

The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA

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14
Q

The process of semi-conservative replication:
The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, what happens?

A

As a result, the double helix:

  1. Separates into its 2 strands
  2. Unwinds
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15
Q

The process of semi-conservative replication:
The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, the double helix separates into its 2 strands and unwinds.
Each exposed polynucleotide strand then acts as a template to which what?

A

Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing

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16
Q

The process of semi-conservative replication:
The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, the double helix separates into its 2 strands and unwinds.
Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing and what form?

A

Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing and hydrogen bonds form

17
Q

The process of semi-conservative replication:
The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, the double helix separates into its 2 strands and unwinds.
Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing and hydrogen bonds form.
What happens to form the ‘missing’ polynucleotide strand on each of the 2 original polynucleotide strands of DNA?

A

Nucleotides are joined together in a condensation reaction by the enzyme DNA polymerase to form the ‘missing’ polynucleotide strand on each of the 2 original polynucleotide strands of DNA

18
Q

The process of semi-conservative replication:
The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, the double helix separates into its 2 strands and unwinds.
Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing and hydrogen bonds form.
Nucleotides are joined together in a condensation reaction by the enzyme DNA polymerase to form the ‘missing’ polynucleotide strand on each of the 2 original polynucleotide strands of DNA.
What form between the nucleotides?

A

Phosphodiester bonds form between the nucleotides

19
Q

The process of semi-conservative replication:
The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, the double helix separates into its 2 strands and unwinds.
Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing and hydrogen bonds form.
Nucleotides are joined together in a condensation reaction by the enzyme DNA polymerase to form the ‘missing’ polynucleotide strand on each of the 2 original polynucleotide strands of DNA.
Phosphodiester bonds form between the nucleotides.
What does each of the new DNA molecules contain?

A

Each of the new DNA molecules contains one of the original DNA strands

20
Q

The process of semi-conservative replication:
The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, the double helix separates into its 2 strands and unwinds.
Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing and hydrogen bonds form.
Nucleotides are joined together in a condensation reaction by the enzyme DNA polymerase to form the ‘missing’ polynucleotide strand on each of the 2 original polynucleotide strands of DNA.
Phosphodiester bonds form between the nucleotides.
Each of the new DNA molecules contains one of the original DNA strands.
What does this mean?

A

This means that half of the original DNA has been:
1. Saved
2. Built into
each of the new DNA molecules

21
Q

The process of semi-conservative replication:
The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, the double helix separates into its 2 strands and unwinds.
Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing and hydrogen bonds form.
Nucleotides are joined together in a condensation reaction by the enzyme DNA polymerase to form the ‘missing’ polynucleotide strand on each of the 2 original polynucleotide strands of DNA.
Phosphodiester bonds form between the nucleotides.
Each of the new DNA molecules contains one of the original DNA strands.
This means that half of the original DNA has been saved and built into each of the new DNA molecules.
Half of the molecules are what and half of the molecules are made up of what, hence ‘semi-conservative’ DNA?

A
  1. Half of the molecules are old DNA
  2. Half of the molecules are made up of new molecules of DNA
    ,hence ‘semi-conservative’ DNA
22
Q

What does the phrase ‘the strands of DNA are complementary’ mean?

A

The phrase ‘the strands of DNA are complementary’ means that:

  1. Wherever there’s a T in one strand, there will be an A in the opposite strand
  2. Wherever there’s a C in one strand, there will be a G in the opposite strand
23
Q

The 2 strands of DNA:

What does each DNA strand have?

A

Each DNA stand has:

  1. A 5 prime end
  2. A 3 prime end
24
Q

The 2 strands of DNA:
Each DNA strand has a 5 prime end and a 3 prime end.
How do the 2 strands run?

A

The 2 strands run in opposite directions

25
Q

The 2 strands of DNA:
Each DNA strand has a 5 prime end and a 3 prime end.
The 2 strands run in opposite directions.
What does this determine?

A

This determines how each strand of DNA is replicated

26
Q

Replication fork

A

A replication fork is how the separated strands each provide a template for creating a new strand of DNA

27
Q

Which enzyme is involved in the separation of the 2 strands of DNA?

A

DNA helicase is involved in the separation of the 2 strands of DNA

28
Q

Which enzyme is involved in adding bases to a DNA template strand?

A

DNA polymerase is involve in adding bases to a DNA template strand

29
Q

Which enzyme seals up the strands of DNA?

A

DNA ligase seals up the strands of DNA

30
Q

In what direction does DNA replication occur?

DNA polymerase can only do what in one direction?

A

DNA polymerase can only add bases in one direction

31
Q

In what direction does DNA replication occur?

DNA polymerase can only add bases in one direction - how?

A

DNA polymerase can only add bases in one direction - from the 5 prime end to the 3 prime end

32
Q

In what direction does DNA replication occur?
DNA polymerase can only add bases in one direction - from the 5 prime end to the 3 prime end.
What is made continuously?

A

One of the new strands of DNA, the leading strand, is made continuously

33
Q

In what direction does DNA replication occur?
DNA polymerase can only add bases in one direction - from the 5 prime end to the 3 prime end.
One of the new strands of DNA, the leading strand, is made continuously.
The DNA polymerase adds bases one by one in the 5 prime to the 3 prime direction.
Why can the other strand, the lagging strand, not be made in this continuous way?

A

The other strand, the lagging strand, cannot be made in this continuous way, because it runs in the opposite direction

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