Download Ch9notes

Ch 9 - DNA – The genetic material
Vaccine –
Griffith’s experiment –
Figure -2
Types of S. pneumoniae bacteria –
 Smooth edged(S) – has capsule, is VIRULENT
 Rough edged(R) – NON VIRULENT
 S bacteria  R bacteria  Heat killed S bacteria  Heat killed S bacteria + R bacteria -
Live R bacteria took up the capsule and converted to the S strain by ________________.
It is the change in genotype when cells take up foreign genetic material.
AVERY – concluded that DNA is responsible for transformation
HERSHEY & CHASE –
They worked with _______________________. It is a virus that infects bacteria and
produces more viruses when the bacterial cell ruptures.
They used _______ phages to infect ___________ bacterial cell. They used radioactive
_________ to label the protein coat and __________to label the DNA core .The DNA of
viruses were injected into bacterial cells while the proteins remain outside. Their
experiment showed that DNA is the heredity material.
1
Draw Figure-3 and Write out the main steps
2
Structure of DNA
Double helix – 2 strands twisted around each other and made up of _____________
which in turn are made up of a phosphate group, 5 carbon sugar (_________________)
and a nitrogen base.
Nitrogen bases are of 4 types:
___________________
___________________
____________________
____________________
CHARGAFF’s rule
In a given organism,
WILKINS & FRANKLIN’s photographs
Used X-ray diffraction – a beam of X ray was directed towards an object and it bounces
off and creates patterns on a film. This helps analyze the structure.
3
WATSON & CRICK model (1953)
Pairing between bases
Base pairing rules – Purines pair with pyrimidines
Replication of DNA
 It is the process of making a copy of the DNA
 Happens during the ______ phase of the cell cycle
Draw, label and write out the steps in Figure 9
PROOFREADING – DNA polymerase can only add a nucleotide when the previous base
was matched correctly.
Prokaryotic and Eukaryotic DNA have different number of replication forks. Replication
may occur in both directions in both cases.
4