DNA replication Flashcards
(23 cards)
Hersey and Chase Experiment
Wanted to determine whether proteins or DNA functioned as the genetic material
Used a bacteriophage virus and E. coli bacteria and performed experiments with ‘labelled’ proteins (35S) and DNA(32P)
Determined DNA was the genetic material
Structure of DNA nucleotide
sugar mol attached to a phosphate group with a nitrogen base
Bases pair with bases
A-T, G-C
Nitrogen Bases
Are complimentary to each other and run antiparrallel
Direction of DNA replication
5’ to 3’
What are Telomeres
Repeating DNA sequence at the end of a chromosome, they protect coding regions from being lost during replication
Hayflick Limit
cause aging
Times a cell can divide
50
Telomere location
End of chromosome
Telomerase Function
lengthen the number of telomeres on the end of DNA by adding the enzyme telomerase
Telomerase in cancer
repairs the cancer cell after dividing
Helicase
Unwinding the DNA by breaking H-bonds
Gyrase
Making sure DNA doesn’t wind back up again after seperation
SSBP
Attach to exposed DNA to prevent rejoining of DNA
DNA Polymerase III
Catalyzes formation of sugar-phosphate bond between mols
DNA primase
Builds short strand of RNA so polymerase III can attach
DNA polymerase I
Removes RNA primers and replace them with DNA nuceotides
DNA ligase
Joins the Okazaki fragments together
DNA polymerase II
Fixes errors
Semiconservative replication
Each strand of the original molecule is used as a template for each new, complementary strand
Replication in leading strand
Replicated continuously towards the replication fork.
Replication in lagging strand
Replicated discontinuously away from the replication fork. DNA polymerase III must continually re-attach to the strand. Therefore, RNA primase must keep building RNA primers for the enzyme to attach. A series of short strands of DNA are built on the lagging strand that must be removed.
Telomeres in replication
Stabilize ends of chromosomes. Protect the ends from fusing together. Loss of them leads to aging.
