Zusammenfassung der Ressource
3.1.5.2 DNA Replication
- Genome
- Collective of all the DNA in a cell
- PROK
- Loop of naked DNA and plasimids
- EUK
- Nucleus, Mitochondria and Chloroplasts (plants)
- Cell replication
- Binary fission
- Mitosis
- Mitosis
- S Phase
- Replication of DNA
- G2
- replication of Chloroplasts and
Mitochondria DNA
- G1
- Interphase
- Everything BUT Mitosis
- DNA
- 23 Pairs of chromosomes
- If DNA was a language
- Genes would be paragraphs
- Chromosomes would be books
- Process of DNA Replication
- 1) Unwinding DNA
- Gyrase
- 2) Unzipping DNA
- DNA Helicase
- 3) Synthesis new strand
- DNA Polymerase
- 1.Free activated nucleotides
align + H-bond to
complementary base
- 2. DNA Polymerase catalyses the
addition of bases in the 5'-3'
direction
- Bases are added to the 3' end of the new strand
- 3. Condensation of activated nucleotides joining
the nucleotides together by phosphodiester
bonds
- 4. Joining of fragments of
lagging strand by ligase
enzyme
- Activated nucleotides?!
- Nucleotide w/ 3 phosphate groups attached
- Hydrolysis of 2 phosphate groups provide
energy for the bond between nucleotides
- Energy ∴ provide energy for DNA synthesis
- ATP, CTP, GTP, TTP
- DNA replication = active process
- Semi-conservative replication
- Conserve half and the molecules and the other half is new
- PROK
- Form a bubble w/the daughter strands in it
- Mutations
- 1 in10⁸ bases
- doesn't necessarily harmful
- Meselsohn + Stahl had 3 facts to prove semi-conservative replication
- 1) All bases in DNA contain nitrogen
- 2) ¹⁴N isotope is lighter than ¹⁵N isotope
- 3) Bacteria must incorporate N from their growing
medium into any new DNA
- Experiment
- (1) Firstly they grew bacteria in ¹⁵N
- (2) Extract a sample of the DNA (control)
- (3) Extract bacteria
- (4) Put in ¹⁴N medium
- (5) remove sample after 1st round of replication
- (6) 2nd sample removed after 2nd round of replication
- (7) Take 3rd sample after 3rd replication
- 2.1 Extract the DNA
- 2.2 Suspend in CSCl
- Allows DNA to float @ different depths
depending on its density
- 2.3 Centrifuge
- Allow different layers to separate