The Molecular Basis of Inheritance Flashcards
The discovery of the genetic role of DNA began with research by whom?
Frederick Griffith
What are Chargaff’s rules?
- The base composition of DNA varies between species
- In any species the number of A and T bases is equal and the number of G and C bases is equal
What did Franklin conclude about the DNA strand?
Two outer sugar-phosphate backbones, with the nitrogenous bases paired in the molecule’s interior
What were the three competing models?
- Conservative
- Semiconservative
- Dispersive
What is a replication fork?
A Y-shaped region where parental DNA strands are being unwound
What are helicases?
Enzymes that untwist the double helix at the replication forks
What do single-strand binding proteins do?
Bind to and stabilize single-stranded DNA
What does topoisomerase do?
Relieves the strain of twisting of the double helix by breaking, swiveling, and rejoining DNA strands
What do DNA polymerases require?
A primer to which they can add nucleotides
The initial nucleotide chain is a what?
A short RNA primer
What is the initial nucleotide chain synthesized by?
The enzyme primase
How long is the initial nucleotide chain?
Five to ten nucleotides long
What enzymes catalyze the synthesis of new DNA at a replication fork?
DNA polymerases
What do most DNA polymerases require?
A primer and a DNA template strand
Where do DNA polymerases add nucleotides to?
Only the free 3’ end of a growing strand
