Today’s Outline DNA and DNA Replication Review – Leading Strand vs. Lagging Strand – DNA Pol I...
-
Upload
jasper-perkins -
Category
Documents
-
view
219 -
download
1
description
Transcript of Today’s Outline DNA and DNA Replication Review – Leading Strand vs. Lagging Strand – DNA Pol I...
Today’s Outline• DNA and DNA Replication Review
– Leading Strand vs. Lagging Strand– DNA Pol I vs. DNA Pol III
• Telomeres• Molecular Sculpting
– DNA Replication– PCR
• What’s Due?– StudyNotes 7 is due on Thursday Mar 21– HW # 5 and is due on Tuesday Mar 26.– StudyNotes 8a is due on Tuesday Mar 26.
hydrogen bonds
Strand
3’ carbon 3’ carbon
5’ carbon 5’ carbon
A DNA Double Helix has a regular, repeated structure
DNA Polymerase III
Adds dNTPs to the newly synthesized strand on the leading strand. Adds to the 3’ end of a ribose.
DNA Polymerase I
DNA Primase creates primers (red) that are RNA molecules. DNA Pol I replaces the RNA nucleotides with DNA nucleotides.
Ends of parental DNA strands
Leading strandLagging strand
Lagging strand
Last fragment Previous fragment
Parental strand
RNA primer
Removal of primers and replacement with DNA where a 3 end is available
Second round of replication
New leading strand
New lagging strand
Further rounds of replication
Shorter and shorter daughter molecules
5
3
3
3
3
3
5
5
5
5
53
DNA Pol1 Can only add nucleotides to the 3’ end of existing DNA.
Telomeres protect an organism’s genes from being eroded during successive rounds of DNA replication. In humans the sequence TTAGGG is repeated between 100 and 1000 times.
Molecular SculptingTwo Models:
1. DNA Replication – must include:– Helicase, topoisomerase, single strand binding
proteins, DNA primase, the sliding clamp, DNA pol I, DNA pol III and ligase.
– Okazaki fragments, RNA primers, leading strand, lagging strand, nucleotides and free dNTPs.
2. Polymerase Chain Reaction – must include:– Three panels: denaturing, annealing and extending.– DNA, forward and reverse DNA primers, taq
polymerase, dNTPs.