Chapter 12: DNA Replication Flashcards
What are the models proposed for DNA Replication?
-conservative
-dispersive
-semi-conservative
In the “Conservative” model of replication
the original DNA strands reform original double helix or the two new DNA strands form a new double helix
In the “dispersive” model of replication
-original DNA strands break down into pieces
-new DNA reassembled as a mix of old and new pieces of DNA
In the “semi-conservation” model of replication
-original DNA strand remains intact and combines with a new DNA strand
Equilibrium Density Gradient Centrifugation
-Measelson and Stahl: cells can incorporate either a light nitrogen isotope 14N or a heavy 15n isotope into their nitrogenous bases
-seperate molecules based on density
-heavy DNA with 15N will move toward the bottom, light DNA 14N will remain closer towards the botoom
Circular chromosome
bacteria
linear chromosome
eukaryote
Bacteria has a _____ of replication (ORI)
single origin
Eukaryotes have _______ of replication
multiple origins
__________of linear molecules require special replication
the ends
Requirements for replication
- template of a single stranded DNA
- substrates (new dNTP nucleotides)
- Enzymes to read and assemble nucleotides into new strands
DNA replication is
bidirectional; forming a replication bubble and two replication forks
A replication fork is a
point at which the two. strands of DNA are separated to allow replication at each strand
DNA is synthesized in
the 5’ to 3’ direction ; DNA pol catalyzes the formation of a phosphodiester bond by joining the 5’ phosphate group
Template strands are
antiparallel
