Nucleic acids are made of nucleotides.
what 3 things make a nucleotide (monomer)?
1. PO43- (gives the negative charge on nucleic acids)
2. pentose sugar
3. nitrogenous base
DNA vs RNA
in Pentose sugar
2' is either H or OH
Name the bonds formed between monomers of Nucleic acids.
Phosphodiester bonds (Bond is between 5' and 3')
What are the cyclic nitrogen-containing bases?
in RNA and DNA and hydrogen bonding number?
RNA: A,C,G,U
DNA: A,C,G,T
A-T = 2 H+ bond
G-C = 3 H+ bond
DNA directionality
parallel or antiparallel?
antiparallel
(imagine knuckle on hand, each bump is a sugar connecting to fingers (base), the in between knuckle is phosphate group. use both hands and grap onto fingers. one hand should be upside down. the thumbs point in the directions. the directions are opposite. thus antiparallel).
T/F
only the upper strand can serve as template
False!
both can serve as template
Replication is semi-conservative.
what does this mean?
DNA replication = 2(1 parent with 1 daughter)
like the parent trap movie. the two lindsey lohans split with their mom or dad. (but really, there's only one lindsey lohan in that movie)
DNA template is read in what direction?
DNA is synthesized in what direction?
1. read 3' to 5'
2. synthesized 5' to 3'
DNA synthesis begins where?
replication bubbles (origins)
How many forks in a replication bubble in DNA replication?
2, in opposite directions
Replication requirements in DNA (5)
1. replication bubble
2. DNA polymerase (adds to 3' end)
3. template
4. PRIMER
5. 4 dNTPs
where does energy come from to do replication?
cleavage between alpha and beta phosphates on previous dNTP
Leading strand
synthesized continuously
toward the fork
lagging strand
synthesized discontinuously (Okazaki fragments)
away from fork
Helicase
breaks HYDROGEN bonds to separate strands of DNA.
unwinds
rotary engine - goes fast (1000nt per second), use ATP
6 subunits
Single Strand binding proteins
AKA helix destabilizing proteins
AKA replication protein A (RPA) - in Eukaryotes!
keep strands separate (no hairpins or helices formed)
doesn't cover the bases
context: torsional stress
Topoisomerase 1
for 1 tangled piece of double stranded DNA
reversible nuclease that nicks a phosphodiester bond
context: torsional stress
Topoisomerase 2
for 2 tangled pieces of double stranded DNA
reversible nuclease that breaks a helix.
DNA polymerase needs 2 things to do replication
1. primer
2. free 3'OH
context: RNA primers
what makes RNA primers
DNA primase use DNA template with rNTPs.
free 3' OH on RNA primer to synthesize DNA.
MANY primers in lagging strand vs ONE in leading strand.
