Chapter 11- Structure of Nucleic Acids Flashcards
Nucleotides are linked between
5’ and 3’ phosphodiester linkages
Why is RNA less stable than DNA
OH on 2’ makes the 3’ position in RNA more susceptible to non-enzymatic base-catalyzed cleavage
First Parity rule
A%= T%
G% = C%
Second Parity Rule
%purines= %pyrimidines in a single strand
How many base pairs per turn (3.4 nm)
10.5 bp
DNA stacking is stabilized by
hydrophobic interactions
Base stacking has to do with the
stability of the helix
RNA can base pair with complementary
RNA or DNA (paired strands are also anti-parallel)
Pwptidyl transferase activity is performed by the
rRNA (not the associated proteins)
Heat denaturation is:
reversible ( DNA melting)
Unstacked bases have a higher _____ than stacked bases in helix
absorbance (due to disruption of electronic interactions between stacked bases)
Unzipping DNA is like unzipping a zipper in what way?
starts difficult but becomes easier as it goes along
Why does it take more heat to unzip GC bonds than it does with AT bonds
Harder to break 3 bonds than 2.
Native structure
H bonding is satisfied through base pairing
Denatured structure
Most H-bonds are satisfied through water
Energetic contribution from H-bonds is the _____ in the native and denatured structures
Same
Do H bonds stabilize the native structure relative to the denatured state
NO
Why is denaturation favored among bases?
DNA is negatively charged at neutral pH (Charges repel each other)
Net charge on nucleotide monophosphate
-2
Net charge on a nucleotide monophosphate bound to a pentose
-1
Molecule that contains a phosphoanhydride bond
UDP
