DNA Flashcards
what’s the central dogma
process of transcription then translation of DNA to RNA to proteins
components of a nucleotide
phosphate + a nucleoside (base + sugar)
components of a nucleoside
base + sugar
sugar in DNA + RNA + difference
RNA = ribose
DNA = deoxyribose
on carbon 3 DNA nucleotide only has H, RNA has hydroxyl
2 types of bases
purines and pyrimidines
features of purines + examples
- larger than pyrimidines
e. g. adenine + guanine
features pyrimidines + examples
- smaller than purines
e. g. thymine, uracil + cytosine
nucleoside name of each base
adenine - adenosine guanine - guanosine thymine - thymidine uracil - uridine cytosine - cytosine
4 DNA nucleotides
dATP, dCTP, dTTP, dGTP - deoxy guanine triphosphate
4 RNA nucleotides
ATP,CTP, UTP, GTP - guanine triphosphate
type of bond between nucleotides + bonding elements
phosphodiester bond between phosphate of carbon 5 and hydroxyl of carbon 3
nucleotide rules for polymerisation
can only add to free 3 prime end
features of DNA
sugar phosphate backbone, antiparallel strands, bonds hydrogen bonds between bases
two strands + direction
leading 3’ prime - 5’ prime
lagging 5’ - 3’
DNA polymerase addition of nucleotides
only from 5’ to 3’ on DNA polymerase chain
-therefore continuous on leading
features of DNA replication
- semiconservative
- RNA primers required to start
- catalysed by DNA polymerase
- begins at origin of replication
(many origins of replication per chromosome to allow quick replication of DNA)
enzyme that unwinds DNA - resulting structure
- helicase, creates replication bubble
Replication of leading strand
- begins at RNA primer
- DNA polymerase continuously adds nucleotides
replication of lagging strand
- occurs discontinuously
only add from 5’ to 3’ therefor Okazaki fragments produced
DNA as tightly packed chromosome
heterochromatin
DNA as loose packed chromosomes undergoing replication/ transcription
euchromatin
number of bonds between adenosine and thymine in DNA
2 hydrogen bonds
number of bonds between guanine and cytosine in DNA
3 hydrogen bonds
DNA proof reading name + mechanism
exonuclease activity
- removes wrong nucleotides from 3 prime to 5 prime (opposite direction to replication)
requirements for replication of DNA
helicase - unwind DNA (replication bubble)
RNA primer - DNA polymerase can’t bind by its self
enzyme which synthesises RNA primer
primase
