D1.1 DNA replication

DNA Replication

the process that a cell undertakes in order to accurately replicate its DNA.

semi-conservative

one original strand and one new strand

Helicase

Unzips the hydrogen bonds holding the base pairs together

DNA Polymerase III

helps to add the new base and form covalent bonds between them, to form the sugar-phosphate backbone of the new strand

phosphodiester bond

Covalent bond between nucleotides

antiparallel replication

the two sides of the double helix will get replicated in opposite directions

RNA primers

a tool to help the DNA Polymerase begin replication

Primase

RNA primers are synthesized by this

Leading strand

replicated in a continuous pattern as DNA Pol III moves down the DNA strand from 5’ → 3’

Lagging strand

IS STILL REPLICATED FROM 5’ → 3’, but in tiny chunks as the DNA pol III “jumps” from segment of DNA to new segment (discontinuous) 

Okazaki fragments

fragements formed during replication of lagging strand and must be connected to each other by DNA ligase

DNA Polymerase I

moves down the strand and checks for any errors in replication, removes the mistake and replaces it with the correct base, also removes RNA primers and replaces them with DNA

ligase

Ligates, or joins together, the okazaki fragments

Single-stranded binding proteins (SSBPs)

Prevents hydrogen bonds from reforming between separated DNA strands

Polymerase Chain Reaction (PCR)

Amplifies targeted sections of DNA millions of times over

● Heat sample to separate DNA strands

● Cool down so primers anneal to the DNA strand

● Polymerase replicates the targeted sections of DNA

Uses Taq Polymerase, which is from a bacteria that lives in hot spring, so it

can withstand the high temperatures of the hot phase of

Gel Electrophoresis

Separates fragments of DNA by size

Low voltage electric currents move DNA fragments down the gel

Larger fragments stay back towards the well, small fragments travel farther

Gel banding patterns

analyzed to determine if there is a match between different DNA samples