L3: Nucleic Acid Structure & Function Flashcards
parts of a nucleotide
phosphate group
sugar
nitrogenous base
which contains a phosphate group?
nucleosides
or
nucleotides
nucleotides
ribose vs deoxyribose
ribose has OH
deoxy only H
compare locations of glycosidic bond and phosphodiester bond to ribose/deoxyribose oxygen
glycosidic at C1’
OH at C2’
phosphodiester bond at 3’
where does the phosphate group attach to nucleic acid
5’ carbon
opposite side as glycosidic bond
compare purines to pyrimidines
purines have double rings
pyrimidines are single rings
list the purines
Adenine
guanine
list the pyrimidines
cytosine
thymine
uracil
DNA characteristics
storage double stranded deoxy A-T G-C
RNA characteristics
transport, catalysis, regulation single stranded ribose A-U G-C
in DNA, purines always base pair with _______, creating an ?
pyrimidines
antiparallel double helix
different forms of DNA helix structure
B form
A
Z
base pair vs helix axis of the types of DNA
B form — bps are straight across from each other
A and Z — are tilted to 19 and 9 degrees
nitrogenous base orientation of the types of DNA
B and A — normal, both face inwards
Z — purines face out and pyrimidines face in
physiological relevance of the forms of DNA
B — the physiological relevant form
A — primarily seen in RNA
Z — very rare
RNA is usually _____ stranded but can also be _____ stranded by ?
single
double stranded by folding back on itself to create hairpin loop
what is the Mesehlson stahl experiment?
comparing models for DNA replication to discover the mechanism of replication
discovery = semi-conservative replication
nontraditional structures
hairpins
cruciforms
triplexes
quadruplexes
hairpin loops and cruciforms
requires a palindromic sequence = inverted repeat
created by superhelical strain in DNA
triplexes
unknown if occurs in nature
requires homopurine-homopyrimidine duplex
uses hoogsteen hydrogen bonds
quadruplexes
guanines only — meaning only consists of guanines hydrogen bonding to each other
occurs in telomeres and some promoters
melting temp is the temp at which ?
half of the sample is denatured
how does DNA go from 2 strands to single stranded?
starts with lose of A-T bonds
but once denaturation begins it can zipper apart quickly
is absorbance higher in single or double stranded DNA?
single
reforming post - denaturation
DNA can reform once cools down
but proteins cannot always reform
summary of mutation mechanisms from special topics
there are 2 categories of mutations
- altered H bond potentials
- error prone repair of replication roadblocks
