DNA structure Flashcards
Beadle and Tatum
proposed one gene-one enzyme theory
Avery’s Group
DNA is the genetic material passed from parent to offspring and DNA directs protein synthesis (central dogma)
Chargaff’s Group
quantative analysis which was
- A+G =T+ C
- A=T & G=C
Franklin (working for wilkins)
DNA X-Ray analysis and concluded that DNA has a right handed twist and the distance acrross the DNA molecule is equal and consistent.
-she also did not know that xrays cause cancer w/o proper protection so she died of cancer. x-rays break chromosomes
Watson and Crick
figured out the structure of DNA and wrote a one-page paper describing it. They also won the noble prize with wilkins.
-ball and stick model
DNA structure
- nucleotides with nitrogen containing bases with purines (A and G) and pyramidines (T,C, and U)
- pentose sugar
- phosphate group
- alternation withe sugar and phosphate
- weak H-H bonds hold two sides of DNA together and easily breakable for replication
- 2 sides of DNA run antiparelll
DNA’s semi conservative replication
occurs by complementary base pairing
-nucleosomes uncoil and histones and other proteins are removes
-H-H bonds are broken and helicases are used
-creates replication forks and bubbles
-
DNA polymerase
allows nucleotides to come in
helicase
breaks h bonds
primase
builds primer
primer
is a sequence of nucleotides
ligase
hooks together okazaki fragments after primase falls off
okazaki fragments
the 5’ to 3’ strands
telomeres
“tip of the shoelace”.
- stabilize DNA by creating inert ends
- segments shorten with each nuclear division due to RNA’s primer presence
Nucleotide
basic building block of DNA and RNA.
Each nucleotide consists of a base, phosphate and a sugar
purine
double ringed organic bases in nucleic acids
pyramdines
single ringed organic bases in nuclic acids
bubbles and forks
for replication, DNA h-h bonds break for complementary base pairing
template
the “2” old DNA pieces are the template for newly forming complementary DNA sequence
bidirectional
each side is made continuosly from the origins of replication so 3’ to 5’ and 5’ to 3’
leading and lagging strands
- leading strand goes in 5’ to 3’ direction so it continues continously
- lagging strand is the 3’ to 5’ direction and it is discontinous with okazaki fragments
replication
- helicase unzips DNA by breaking h bonds
- polymerase allows the nucleotides to come in for complementary base pairing
- primer allows for replication to start
- ligase hooks together okazaki fragments once the primer falls off
sister chromatids
replicated chromosomes are composed of 2 sister chromatids
