Mod 5: Question 2 Flashcards
1
Q
What is a model?
A
Simplifed representation of a complex system or concept that is usally to small/large to see
2
Q
Advantages vs Disadvantages of models
A
Weaknesses
* may not be accurate
* over simplification can mislead
* lack detail
Advantages
* simligy complex concepts
* have predicitve power
* lead to increased undeerstanding/research
3
Q
History of DNA
A
Levene (1919) discovered nucleic acids are composed of nucleotides
Chargaff (1950) disovered the amount of A=T and G=C
Watson and Crick (1953) found that DNA is a double stranded, helical model
* two sugar-phospahte backobnes with are bonded by hydrogen bonds between two nitrogenous bases
* each strand of the DNA molecule was a template for the other
4
Q
Double helix
DNA structure
A
- twisted ladder held together by four bases
- bases hold genetic infromation which determines the way the DNA is read - red 5’ to 3’ direction
- each base is attatched to a sugar and a phosphate
- run anti-parallel to eachother
- two complementary strands
- h2 bonds and bases form ladder rungs
5
Q
Base Pairing
DNA structure
A
- cytosine, thymine and uracil are pyrimidines - smaller bases
- guanine and edenine are purines - larger bases
despite the two different sized bases they all have the same diameter
