LEC3 and 4 - REPLICATION and TRANSCRIPTION Flashcards
DNA double helix is approximately ___ in nm
2 nm
the double stranded DNA that is intertwimed is attached to a protein called
histone
how many units of histone molecules to form 1 nucleosome
8 histone molecule intertwined in the DNA
it is called as “the core”
nucleosome
proteins involved in epigenesis, rich in arginine and lysine
histone
do prokaryotes have histone?
naur
each core histone subunit will the one that has 8 histone molecules w2ill form ___ approx 10 nm in diameter
nucleosome filament
the nucleosome filament will then contribute in making
fiber - 30 nm
regarded as a string of pearl/ bead of string appearance
nucleosome filaments
the fibers now are folded in _____
looped domain
looped domain is also called as
solenoid
the looped domain or solenoid can be in what shape
tubular, helical, coiled
forms the backbone of the molecule
sugar and the phosphate
connects the sugar and the phosphate
phosphodiester bonds
what makes the double helical DNA stabilize
hydrogen bond
connects the nitrogenous bases together
hydrogen bond
is hyrophobic bond same with hydrogen bond?
yes
The two strands of the DNA double helix are arranged in______; their chemical orientations are different.
antiparallel
opposing orientation of the 2 helical strand
anti parallelism
DOUBLE HELICAL MODEL always follow what model
semi conservative model
a model when replication takes place, the parent cell will stay as it is and will only produce a newly si=ynthesized daughter
conservative replication
parental DNA strands remained together in 1 of the daughter cell the newly synthesized DNA strands went to the other daughter cell
Conservative Replication
each daughter cell received 1 parental DNA
strand and 1 newly synthesized complementary
strand parental strand was the template
. Semiconservative Replication
replication of the strands always happen at ____
5 to 3
the reading of the parental strand happen in what direction
3 to 5
the addition of the template happens in what direction
5 to 3
bonds that connect nitrogenous bases to
pentose sugar
Glycosidic bond
Debunked model
o Replaced by semi-conservative
CONSERVATIVE MODEL
he –
demonstrated semiconservative replication
meselson-stahl experiments
in Meselson-Stahl Experiment, what components he use?
bacteria and nitrogen
o same with semi-conservative
o Here, 3rd generation will have the gene of the
parent
DISPERSIVE MODEL
application of heat or alkaline solution causing the strands to separate but not break the phosphodiester bonds
denaturation
is bidirectional and
semiconservative
REPLICATION
means that replication begins at
a site of origin and simultaneously moves out
in both directions from this point.
Bidirectional
) Prokaryotes have how many site of origin on each
chromosome.
one
Eukaryotes have hwo many sites of origin on each
chromosome
multiple
ORI C means
origin of replication
found in ORI C where in all the replication events will take place inside
replication bubble
inside ORI C, wherein it Forms a V letter shape known as
replication fork
a part where the helicase enzyme lyse
replication fork
replication is always consensus or starting with AT base pairs, why?
because they only have 2 hydrogen bonds as it is easier to separate them compared to CG
HOW MANY HYDROGEN BOND DOES CYTOSINE AND
GUANINE
3
HOW MANY HYDROGEN BOND OF ADENINE AND THYMINE
2
primase is the one that will form
primer (5 - 3`)
the leading strand runs in what direction
5 - 3
unzipping of dna is done by ___ resulting to replication form
helicase
marks the starting point for the construction of the DNA
primer made by primase
binds the primer and will make new strand of the DNA
dna polymerase
the polymerase will add bases one by one in a ____ strand, it will run continuously from 5 to 3
leading strand
in this strand, the polymerase will add bases one by one in small chunks as it runs in opposite direction
lagging starnd
the small chunks made by polymerase is called as
ozaki fragments
each strand is started with what primer
rna primer
it’s function is to remove all the rna primer in both strands
exonuclease
another ___ will fill out the gaps of the removed primar
dna polymerase
this enzyme will glue and seal the strands
ligase
BASIC REQUIREMENTS FOR DNA SYNTHE
SUBSTRATES
TEMPLATES
PRIMER
4 deoxynucleotide triphosphates (dNTPs)
- deoxyadenosine triphosphate (dATP)
- deoxyguanosine triphosphate (dGTP)
- deoxycytidine triphosphate (dCTP)
- deoxythymidine triphosphate (dTTP)
Prepares the template strand for the addition of nucleotides
PRIMER
usually how long is the primer
10 nucleotide long
direct DNA polymerase at the origin of
replication
Primer
always first in the replication
Primer
source of DNA polymerase in vitro
Taq (Thermus
aquaticus)
a type of protein that will initiate the replication
DNA A protein
it will prevent the reannealing of DNA after unwinding of helicase
single stranded binding protein
it creates the enzyme primase
primosome
primer’s direction
3 to 5
what type of polymerase is used by eukaryotes
type D - polymerase D
what type of polymerase is used by prokaryotes
polymerase 3
it will create the subsequent bases until it reach the fork
polymerase in lagging strand
new polymerase that will remove all the primer
polymerase 1 and alpha
polymerase Delta and 3
replication
proof read
repair
polymerase 1 and alpha
exonuclease, and repair
polymerase always happen in what direction
5 - 3
proofreading or repair always happen in what direction
3 - 5
direction of exonuclease
5 - 3
adding of cap on the 5` untranslated end
capping
adding of tail on the 3` untranslated end
Polyadenylation
DNA POLYMERASE I (POL I)
functions
DNA replication
Repair of damaged DNA
Removes RNA primers via its 5′ → 3 exonuclease activity
Proofreading
molecular weight of polymerase 1
103,000 MW
Recognizes mismatched nucleotides →halts
polymerization → 3’ to 5’ exonuclease removes
mismatched nucleotide →polymerization
resumes.
Proofreading
DNA POLYMERASE II (POL II)
function
Some DNA repair processes
Proofreading
no replication