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Higher Biology (SQA) > Unit 1: DNA & The Genome - Key Area 2: DNA replication > Flashcards

Unit 1: DNA & The Genome - Key Area 2: DNA replication Flashcards

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1
Q

enzyme that adds free complementary DNA nucleotides during replication of DNA

A

DNA polymerase

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2
Q

technique used to separate macromolecules such as DNA fragments of different sizes

A

gel electrophoresis

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3
Q

enzyme from hot-spring bacteria used in PCR

A

heat tolerant DNA polymerase

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4
Q

DNA strand which is replicated in fragments

A

lagging strand

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5
Q

DNA strand which is replicated continuously

A

leading strand

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6
Q

enzyme that joins fragments of DNA to make the lagging strand

A

ligase

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7
Q

method of amplifying sequences of DNA in vitro

A

Polymerase Chain Reaction (PCR)

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8
Q

short complementary strand of DNA

A

Primer

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9
Q

formation of identical copies of DNA molecules

A

replication

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10
Q

DNA strand on which a complementary copy is made

A

template strand

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11
Q

define DNA replication

A

involves the production of two genetically identical strands of DNA

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12
Q

when does DNA replication occur?

A

prior to cell division (mitosis and meiosis)

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13
Q

what is DNA replication described as

A

semi-conservation as each daughter DNA molecule ends up with one of the original strands of the parental DNA and one newly synthesized strands.

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14
Q

what is the function of ‘helicase’ in DNA replication

A

causes DNA to unwind

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15
Q

what is the function of ‘ligase’ in DNA replication?

A

joins fragments of DNA on the lagging strand

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16
Q

what is the function of ‘DNA polymerase’ in DNA replication?

A

adds free nucleotides using complementary base pairing to the deoxyribose 3’ end of the new DNA strand that is forming

17
Q

what are the requirements of DNA replication?

A 
> original DNA template 
> free DNA nucleotides
> DNA polymerase 
> primers
> ligase
18
Q

what is the function of a ‘primer’ in DNA replication?

A

binds to the 3’ end of the template DNA strand allowing DNA polymerase to add free nucleotides

19
Q

what is the first step of DNA replication?

A

the double helix structure of DNA is unwound and hydrogen bonds between bases are broken to form two template strands

20
Q

what is the second step of DNA replication?

A

two replication forks form and open the double-strand in opposite directions, exposing the bases

21
Q

what is the third step of DNA replication?

A

A primer binds to each strand of DNA

22
Q

what is the fourth step of DNA replication?

A

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

23
Q

what is the fifth step of DNA replication?

A

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

24
Q

what is the sixth step of DNA replication?

A

Fragments of DNA are joint together by ligase

25
Q

what is PCR (polymerase chain reaction) used for?

A

to amplify a desired DNA sequence

26
Q

what are the requirements of PCR?

A 
> nucleotides
> primers 
> heat tolerant polymerase 
> template DNA 
> buffer
> thermal cycler
27
Q

why does PCR use primers?

A

Polymerase can only add nucleotides to an existing strand of DNA so PCR requires primers

28
Q

why does PCR need two primers per cycle?

A

Because primers are short strands of nucleotides which are complementary to specific target sequences and there are two ends of the region of DNA to be amplified thus requiring two primers.

29
Q

what is the first step of PCR?

A

Heating:
DNA molecule to be amplified is denatured by heating to between 92-98 degrees celsius, breaking hydrogen bonds between base pairs to separate the two strands

30
Q

what is the second step of PCR?

A

Annealing:

DNA is cooled to between 50-65 degrees celsius to allow the primers to bind to target sequences

31
Q

what is the third step of PCR?

A

Extension:

DNA is then heated to between 70-80 degrees celsius for heat-tolerant DNA polymerase to replicate the region of DNA

32
Q

what is the fourth step of PCR?

A

two strands are formed and this cycle is repeated 30 times

33
Q

how is DNA amplified in PCR?

A

in vitro (outside of a living organism)

34
Q

what are the uses/ applications of PCR?

A

> paternity testing
crime scene analysis
diagnosis of genetic disorders

Higher Biology (SQA) (5 decks)

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