DNA Flashcards
Nuclei acids
Primary structure of DNA and RNA, monomers
Role of RNA
To leave nucleus and goes to ribosome to be translated into proteins
Nucleotides
Polymer
Nitrogenous base (pyrimidiques (CTU) and purines (2 cyclic) (AG))
Penrose sugars (ribose of deoxyribose which has 1 less oxygen)
Phosphate group
Important in cellular respiration and coenzymes
Phisphodiester bonds
Linkage between phosphate and sugar of 2 bases
Backbone then is a religion of phosphate and sugars
Hydrogen bonds the bases, in order to be detached easily in translation and transcription
Has a 5’ Phosphtae terminus and a 3’ OH terminus
Griffith’s experiment
Took 2 strands of pneumonia, 1 is pathogenic and causes disease (smooth) , one not.
When injected with smooth, mice dies
Injected with rough p, mice loves
Kills smooth and injects, mice lives
Injectés dead smooth and rough, mice dies
Some chemical compound of the dead smooth caused heritable change in rough, making it smooth too
Alfred Hershey and Martha Chase’s experiment
Noted that when the phage infects a bacteria, it infects with some materials, they wanted to indenting the nature of the material
They took the larges and grew them with either radioactive give sulfur (protein marked) or phosphorus (dna marked)
Then allow pages to infect bacteria
Then check where is the radioactivity, found that the material is in the dna
Rosalind Franklin
Did x ray cristomography to analyze the structure of DNA, but was beaten to publication by crick and Watson after her work was stolen and given to them
DNA replication,
Occurs one once in a cell
G1, S, G2
DNA helicase: séparâtes double stranded dna at the origin where synthesis will begin
Single strand binding protein go on the dna and prevent it from going back to a double strand
Topoisomeras: relieves the supercooling ahead of the dna helicase and facilitate the unwinding by cutting a strand and resceals break, removing a knot
Dna polymerase: repllicates dna, polymérisation stats at 5´ to 3´, requires the template of one of the sgrands, requires 4dNTP: dATP, dGTP, dCTP, dTTP. Needs a primer
1: replaces rna primers with dna
2: places the dna on the leading strand (?)
3: places dna on the lagging strand
Dna polymerase needs a primer, needs hydroxyl group, a starter to start transcription, a couple nucleotides
Primase: couple of RNA nucleotides added by an RNA (primase) to allow dna polymerase to start its transcription
main differences between prokaryotic and eukaryotic DNA replication
One origin in prokaryotes where dna begins, replication starts at origin instead and goes both sides (circular dna) bidirectional
Eukaryotes copy their dna at a slower rate, they have more, so 1 origin isn’t efficient as it would take much more time. So there are multiple originals along the linear dna
Explain why DNA polymerase can only act from 5’ to 3’
5´ phosphtae (?)
3´ hydroxidé
Phosphate hydrolysée to make covalent bonds (?)
Where does the energy to add the new deoxyribonucleoside triphosphate to the growing DNA strand come from?
Describe the difference between synthesis of the leading strand and the lagging strand
One end (5 to 3) is continuous, leading strand
The other (3 to 5) needs to be opened up to be synthesized the other way around, that’s the lagging strand, Okazaki fragments
Makes an rna primer at every begining of fragments, then dna polymerase removes rna primers and replaces it with dna, leaves a space called a nick, and then dna ligament forms the bond between the new dna and the old dna (fills the nick)
Campbell 7 book good
replisome
Why does repeated rounds of replication produce shorter and shorter DNA molecules in the lagging strand?
telomerase
