7.1 DNA Structure and Replication Flashcards
1
Q
Outline Hersey and Chase
A
- Proved that DNA is the genetic material
- Grew viruses in radioactive sulfur (in protein not DNA) or radioactive phosphorus (in DNA not protein)
- Infected E.coli bacteria with the viruses
- Seperated bacteria and virus via centrifugation, produced a pellet
- The pellet contained radioactive phosphorus
2
Q
What did Rosalind Frankling do?
A
- Worked at Kings College in London during the 1950’s
- Used X-ray crysallography to obtain a 3d picture of DNA
- Showed that DNA is double stranded, that phosphate groups need to be on the outside, and that DNA is a helix
3
Q
What did Watson and Crick do?
A
- Used Franklin’s picture to help them in creating a DNA model
- Found that the bases can not be too far away from eachother
- Found that a purine needs to be bonded to a pyrmidine
- Led to the hypothesis of semi-conservative replication
4
Q
Purines
A
- Adenine
- Guanine
5
Q
Pyrmidines
A
- Cytosine
- Uracil
- Thymine
6
Q
What DNA is associated with histones?
A
Eukaryotic DNA
7
Q
What is considered naked DNA?
A
Prokaryotic DNA, since it is not associated with histones
8
Q
What does histones do?
A
They pack eukaryotic DNA into nucleosomes
9
Q
What are nucleosomes?
A
A nucleosome is 8 histones with DNA wrapped around them. They are connected via short sections of DNA
10
Q
What are the bennefits of nucleosomes?
A
Nucleosomes contribute to supercoiling, which allows long strands of DNA to be packed in a smaller space in the nucleus. This helps eukaryotes in packing their large genome.
