Dna Replication

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This step unzips the double helix structure of the DNA molecule

First step

This step is carried out by an enzyme called helicase

Second step

This enzyme breaks the hydrogen bonds holding the bases of DNA together

Helicase

This step is the separation of two single strands of DNA which will act as templates for making new strands

third step

These are two single strands of DNA that create a 'Y' shape

replication fork

What bond does the sugar and phosphate group have?

Covalent bond

What direction is the strand towards the replication fork?

3' to 5'

What strand has a 3' to 5' direction and where does it face ?

leading strand and towards the replication fork

What strand has a 5' to 3' direction and where does it face ?

lagging strand and away the replication fork

What direction is the strand away from the replication fork?

5' to 3'

This is a short piece of RNA that binds to the end of the leading strand

primer

What enzyme produces primers?

Primase

What binds to a DNA strand and adds new nucleotide bases to the strand of DNA?

DNA polymerase

What does the DNA polymerase need in order to start?

primers

What sort of replication needs one primer and polymerase to start?

Continuous replication

How many primers does the lagging strand need?

Numerous

These are chunks of DNA that are added to the lagging strand

Okazaki fragments

What direction are the Okazaki fragments?

5' to 3'

What sort of replication needs numerous primers which create okazaki fragments?

Discontinuous replication

This enzyme strips away the primers

exonuclease

This enzyme seals up the sequence of DNA into two continuous double strands

DNA Ligase

What is the result of DNA replication?

Two DNA molecules consisting of one new and one old chain of nucleotides

What is DNA replication described as?

Semi-conservative

Where does DNA replication occur?

nucleus

When does DNA replication occur?

Interphase (before mitosis or meiosis)

What is Primase made of?

RNA

What protein keeps the strands of DNA from bonding?

Single stranded binding proteins

This enzyme prevents DNA from tangling together

topoisomerase

What direction does DNA polymerase build a new strand?

5’ to 3’