Structure And Replication Of DNA Flashcards

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1
Q

What does the base sequence of DNA form?

A

The genetic code

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2
Q

What is DNA composed of?

A

DNA is composed of nucleotides containing deoxyribose sugar, phosphate and a base.

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3
Q

What is a nucleotide?

A

A nucleotide is an organic molecule composed of a nitrogenous base, a deoxyribose sugar and a phosphate group.

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4
Q

What forms the sugar phosphate backbone?

A

Strong chemical bonds between the phosphate ( 5’ ) and the deoxyribose sugar ( 3’ )

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5
Q

What do sugar phosphate bonds hold together?

A

Sequences of nucleotides that form DNA

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6
Q

What are the four bases on DNA?

A

Adenine, Thymine, Cytosine and Guanine

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7
Q

What are the base pairing rules on DNA?

A

Cytosine bonds with Guanine and Adenine bonds with Thymine

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8
Q

What are the complementary bases between nucleotides joined together by?

A

Hydrogen bonds

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9
Q

What is the term used to describe how both strands of DNA run in opposite directions to eachother?

A

Antiparallel

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10
Q

What is meant by antiparallel?

A

Antiparallel is a term used to describe how each strand of DNA runs in opposite directions ( one runs from the 5’ end to the 3’ end and the other runs from the 3’ end to the 5’ end )

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11
Q

What is a term to describe the structure of DNA?

A

Double stranded Antiparallel helix

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12
Q

When does DNA replication take place?

A

DNA replication takes place prior to cell division

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13
Q

What enzyme unwinds DNA

A

Helicase

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14
Q

What is the first stage in DNA replication?

A

The hydrogen bonds between bases are broken to form two template strands

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15
Q

What is a primer and what is its role in DNA replication?

A

A primer is a short sequence of nucleotides which binds to the 3’ end of the template DNA strand to begin replication

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16
Q

What enzyme replicates DNA?

A

DNA Polymerase

17
Q

What is the function of DNA polymerase?

A

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

18
Q

Why is there a leading and lagging strand?

A

DNA polymerase can only add DNA nucleotides in one direction resulting in the leading strand being replicated continuously and the lagging strand replicated in fragments

19
Q

What enzyme joins fragments together?

A

Ligase

20
Q

What is PCR?

A

PCR ( polymerase chain reaction ) amplifies DNA using complementary primers for specific target sequences

21
Q

What is the use of primers in PCR?

A

Primers are short strands of nucleotides which are complementary to specific target ic sequences at the two ends of the region of DNA to be amplified

22
Q

What is PCR in terms of cycles?

A

PCR is repeated cycles of heating and cooling to amplify the target region of DNA

23
Q

What is stage 1 of PCR?

A

DNA is heated to 95 degrees celcius in order to break the hydrogen bonds between strands

24
Q

What is stage 2 of PCR?

A

DNA is cooled to 60 degrees celcius in order to allow primers to bind to specific target sequences

25
Q

What is stage 3 of PCR?

A

DNA is heated to 75 degrees celcius in order to allow * heat tolerant * DNA polymerase to replicate the region of DNA

26
Q

What are three uses of PCR?

A

3 uses:
Settling paternity suits
Solving crimes
Diagnosing genetic disorders