Biology Unit 1 - Replication of DNA

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What is the process of DNA replication
the process by which DNA molecules can direct the synthesis of identical copies of themselves
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Do DNA molecules replicate before or after cell division
before
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What is PCR?
a laboratory technique that is used to produce millions of copies of specific target sequences of DNA
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Where is PCR carried out?
in vitro (outside of the organisms body)
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Give 2 applications of PCR
1. in forensics it can be used to amplify small amounts of DNA from crime scenes such as blood or *****. 2. amplifying the DNA for the study of related species to show their true place in evolution
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In the first step of PCR what temperature is the DNA heated to and why?
90 degrees which causes the DNA to denature and therefor the strands to seperate
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In step 2 of PCR what temperature is the DNA heated to and why?
Cooled to 60 degrees which allows the complementary primers to bind to specific target sequences
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In step 3 what temperature is the DNA heated to and why?
raised to over 70 degrees when heat tolerant DNA polymerase is used to synthesise new strands from free DNA nucleotides
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where does PCR usually take place?
there are usually automated in a thermocycling machine
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what is Taq polymerase?
heat tolerant DNA polymerase
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Stage 1 of DNA replication
double helix unwound by an enzyme & the hydrogen bonds which attach the two strands are broken causing it unzip forming a replication fork
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Stage 2 of DNA replication
Primers join the 3' end of the 3'-5' end of the lead template strand & the DNA polymerase adds free complementary DNA nucleotides to synthesise a complementary strand continuously
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What is a primer?
short complementary sequences of nucleotides that allow DNA polymerase to bind
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What is DNA polymerase?
enzyme which adds free complementary DNA nucleotides during replication of DNA
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Stage 3 or DNA replication
On the lagging strand primers are added one by one into the replication fork as it widens. DNA nucleotides are added in fragments. These fragments are then joined by DNA ligase to form a complete complementary strand. The process requires energy
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How is the energy produced in DNA replication?
supplied by ATP produced by the cell's respiration
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Why is DNA replication important?
it ensures that identical copies of the genetic information of a species are passed on from cell to cell and from generation to generation
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How is the leading strand replicated ?
continuously
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How is the lagging strand replicated?
in fragments
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Card 2

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Do DNA molecules replicate before or after cell division

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before

Card 3

Front

What is PCR?

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Card 4

Front

Where is PCR carried out?

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Card 5

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Give 2 applications of PCR

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