lec 1: dna structure Flashcards
the bacteria used for griffith experiment
Streptococcus pneumoniae
worked with virulent S and nonvirulent R strain P. bacteria
Fred Griffith
rough strain is what and the mouse is what?
avirulent, mouse lives
smooth strain is what and the mouse is what?
virulent, mouse dies
heat-killed smooth strain is what and the mouse is what?
avirulent, mouse lives
rough strain and heat-killed strain is what and the mouse is what?
virulent, mouse dies
griffith found that R strain could become virulent when it took DNA from heat-killed S strain
transformation
this experiment first suggested that DNA was probably the genetic material
transformation (griffith experiment)
32P radioisotope is for
DNA
35S radioisotope is for
protein capsule
steps in hershey and chase experiment
infection
blending
centrifugation
showed the amounts of the four bases on DNA ( A,T,C,G)
erwin chargaff
chargaff’s rule: in a body or somatic cell, give the percentage of each base
A = 30.3%
T = 30.3%
G = 19.5%
C = 19.9%
this evidence of molecular diversity among species made DNA a more credible candidate for genetic material
chargaff’s rule
- Adenine must pair with Thymine
- Guanine must pair with Cytosine
chargaff’s rule
the nucleotide bases form ____ from each other
weak hydrogen bonds
took diffraction x-ray photographs of DNA crystals
rosalind franklin
built the first model of DNA using Franklin’s x-rays
james watson
francis crick
immediately suggests a possible copying mechanism for the genetic material
specific pairing
base + pentose sugar =
nucleoside
base + pentose sugar + phosphate group =
nucleotide
give the pyrimidine bases
thymine
uracil
cytosine
give the purine bases
adenine
guanine
n-base is connected to what carbon position in sugar?
1’
