Topic 3 Flashcards
What is a nucleoside
What is a nucleotide
Sugar and base
Sugar base and phosphate
Why is dna called deoxyribose
No oh on 2’ carbon
Just H
What is a phosphoester bond
The bond between the phosphoric acid and the 5’ oxygen of the sugar
Just phosphoester, if whole dna it is phosphodiester
What is the glycosidic bond between in dna
The 1’ carbons OH and the nh of the base
Purines
Pyrimidines
Adenine guanine
Cytosine thymine
Recongnicze AGCT structures
Slide 6
Double helix orientation of strands
Antiparallel
Phosphodiester bond is how many linkages
Phosphoester
2
1
What method helps us to see the dna size
Agarose Gel electrophoresis, smaller further, larger slower
How many h bonds are between A-T
G-c
2
3
What are the two dna chains stabilized by
Perpendicular Base pairing and stacking
What causes the GC bases to be stronger binded together
The benzene ring like structures in the g and c bases causes the hydrophobic force to be greater and pushes the bases close together
Recording slide 10
What causes pi stacking
The hydrophobic effect dues to vanderwalls forces
More in red slide 10
Is dna right handed or left handed
Right handed
If base faces in toward the sugar its
If our away from sugar
What type of twistings do these cause
Syn (left hand twisting)
Anti (right hand twisting)
What determines the orientation of bases (anti or syn) in the dna
The glycosidic bind that’s connecting them to the sugar
What are isomers
Same formula different structure
Give examples of two isomers
Amide to imidic acid (the h on the N goes to o)
Enol to keto ( oh on enols goes to ch)
What are tautomers
Isomers that are interconverted by migration of a hydrogen atom
Give an example of how cytosine becomes a tautomer and how the h bond donors and acceptors in it change
The nh2 amino (was a donor) loses H and now becomes acceptor
Slide 12
Give an example of how guanine becomes a tautomer and how the h bond donors and acceptors in it change
The nh gives it h to c=O
Not the c=o that was acceptor becomes c-oh donor
Slide 12
What can cause misplacing between bases
Slide 13
What are tautomeric shifts
Random rearrangements of the nitrogenous bases (due to tautomerization)
lets h binding happen between base pairs that don’t usually pair together (mismatched)
What happens after dna replication if a tautomeric shift causes GT and not Gc pairing
Recording slide 14