Overview of DNA and structure Flashcards
What gets packaged to make chromosomes?
DNA
What are the three required properties of dna?
- Must allow for accurate replication (when cells divide each cell needs accurately replicate to be in the new cell)
- Must contain information
3.Must be able to change (rarely)- has to give mutations
What are the three basic components of dna?
phosphate back bone, sugar (deoxyribose), and base
What kind of bases are in dna?
Purines and Pyrimadines
What are the type of purines?
A and G
What are the type of pyrimidines?
C and T
Nucleotides must have how may phosphates? How many can they have upto?
Must have 1, can have upto 3
Where is the OH on the sugar in DNA? Is this important?
on the three prime carbon, is important for synthesis
In double stranded DNA, how much A+G and T+C is there?
An equal amount, A+G = T+C
In double stranded DNA, is there equals amounts of paired nucelotides?
Yes, G= C and A=T
What does it mean if an organisms DNA is GC rich?
It means that some organisms have more GC content
After every _____ base pairs, dna twists
10 bp
In what direction does DNA twist?
Right
What are phosphodiester bonds?
Is the 3’ carbon of sugar of one nucletide, bonding to the 5’ carbon of another sugar via a phosphate group
What kind of orientation does the two dna strands show?
antiparrellel, one is 5’ to 3’ other is 3’ to 5’
Why is dna with more GC content stronger?
Is more GC rich, G-C has three bond smore H bonds so stronger
Whats the difference betwen purine and pyrimidines?
purine- two rings
pyrimadine- one ring
What experiment confirmed that dna replicates in a semi conservative manner?
meselson-stahl experiment
What replicates DNA?
DNA polymerase
What happens in catalyzing DNA that produces energy for the rxn?
pyrophosphate (two extra phosphates) gets cleaved, this produces energy to drive dna synthesis
new nucleotides can only be added in what direction?
The 5’ to 3’ direction, because the 3’ sugar needs to bond to the phosphodiester which bonds to the 5’ of the next sugar.
How does DNA get synthesized?
unwinding- single strand DNA binding proteins unwind DNA, helicase facilitates this by disrupting H bonds
Leading strand gets synthesized- leading strand template in 3’ to 5’ serves as template for leading strand in 5’ to 3’ direction, DNA polymerase three does this by building off primers made by primase
Lagging strand gets synthesized from template in 5’ to 3’ direction, so the lagging strand gets synthesized in chunks by poleymerase three working off primer.
B Clamp starts DNA synthesis, and okazaki fragmets are refined by polymerase 1 as it removes primer with nucelotides and fills gaps, and ligase joins the fragments
gyrase rejoins dna strands
What kind of bonds does DNA ligase catalyze?
phosphodiester bonds
How long are primers made by rna primase?
11 bp long
