4 .1 History of DNA and Review of DNA Structure Flashcards
Griffith and Transformation
researching pneumonia
gave mice different strains of bacteria
1. virulent S strain - mouse died
2. nonvirulent R strain - mouse lived
3. heat-killed virulent S strain - mouse lived
4. 2 + 3 - mouse died
transformation factor
Avery and DNA
wanted to know what the transformation factor is
S strain -> centrifuge -> heat kill -> remove proteins, carbohydrates, and lipids
1. R strain + S strain filtrate - transformation occurred
2. R strain + protease treated S strain filtrate - transformation occurred
3. R strain + ribonculease treated S strain filtrate - transformation occurred
4. R strain + deoxyribonuclease treated S strain filtrate - no transformation
transformation factor is DNA
Hershey-Chase
two batches of bacteria
1. radioactive protein shell
2. radioactive DNA
bacteria infected with viruses
blended and centrifuged to separate viruses and bacteria
only bacteria infected with radioactive DNA viruses were radioactive
- DNA is genetic material
Chargaff’s 1st rule
Adenine (A) = Thymine (T) and Guanine (G) = Cytosine (C)
Chargaff’s 2nd rule
the amounts of A, C, G, and T vary from species to species
Watson and Crick
phosphates must be on outside of a DNA molecule
DNA is composed of two strands
strands form a double helix
the nitrogenous bases pair in the middle like ladder rungs
parts of a nucleotide
- phosphate
- sugar
- nitrogenous base
pyrimidines
T and C
purines
A and G
DNA vs RNA: DNA
sugar - deoxyribose
double-stranded
double helix
A = T
DNA vs RNA: RNA
sugar - ribose
single-stranded
shape depends on folding
A = U (Uracil)
DNA vs RNA: Both
nucleotide (phosphate, pentose sugar, nitrogenous base)
sugar-phosphate backbone
base pairing w/ hydrogen bonds
A, C, G
G = C
antiparallel
antiparallel: complimentary DNA strands run in opposite directions
numbering carbons
1’ at carbon N base is attached to. go counterclockwise
ends of a DNA strand
phosphate group at 5’ end. hydroxyl at 3’ end.
