DNa replication pt 2 Flashcards
(22 cards)
what is Chromatin
the complex of DNA and protein that
make up the Eukaryotic chromosome ( when the cell
is not dividing chromatin exists in its dispersed form,
as a mass of very long, thin fibers that are not visible
with a light microscope.
What does a double helix has
- strands connected by h bonds
- polarity
- complementary strands held by h bonds
- anti parallel run in opposite directions
Who proved that dna is semi conservative
Meselson and stahl
4 steps of dna replication
-unwinding of strands
-initiation of replication
/ elongation if the dna strands being replicated
-termination of replication
Where does replication start
- origin of replication
- makes bubbles along chromosomes
- when finish ->two day get dna molecules
What is a replication bubble
Two forks for each bubble
- lagging strand gas Okazaki fragments
What’s is the replication fork
Parental strands are being unwind and replication of dna takes place
What is helicases
Enzymes that untwist the double helix at the replication fork separating the 2 strands and making them available as templates
What’s is topoisomerase
An enzyme that breaks swivels and rejoins dna strands. During dna replication topoisomerase helps relieve strain in the double helix ahead of the replication fork
What are single strand binding proteins
Proteins that bind to unpaired dna strands they stabilize then and hold them apart while they serve as templates for complementary dna strands
What is primase
A. R a polymerase that hounds dna nucleotides to make the primer using the parental dna strand as a template
What is DNA polymerase 3
Enzymes that elongate the new dna by adding nucleotides to the 3’ end of an existing chain.
Elongates in the 5’ to 3’ direction and reads in the 3’ to 5’ direction m.
Proofreading activity
What does DNA polymerase 3 need to add nucleotides to a free 3’
Primase
Polymerase 3 the. Adds deoxiribonucleosides to that short primer
What is DNA polymerase 1
And enactment that removes and replaces the dna primer
What is Ligase
Man enzyme that ligats ends of dna molecules
Synthesis of lagging stand functions
Primase - priming for Okazaki fragment
Dna 3 polymerase- elongation of fragment
Poly 3- replacement of ran primer by dna
Ligase - joining of dna strands
Synthesis of leading strand
Primase - priming of the leading strand
Dna 3- elongation
Dna 1- replacement if Eva primer by dna
Ligase - joining of dna strands
DNA polymerase proofreading
Mismatched nucleotides evade proofreading or they occur after dna replication because if the exposure of cells to insults such as chemical carcinogens and UV light
What is methylation of histones
methyl groups are transferred to amino acids of histone proteins that make up nucleosomes, which the DNA double helix wraps around to form chromosomes.
what is Euchromatin
The less condensed form of
eukaryotic chromatin that is available for transcription
what is Heterochromatin
chromatin that remains highly
compacted during interphase and is generally no
transcribed
central dogma
replication (dna)–trandscription–>mrna (messenger- carries information in genes)–translation–>proteins (acotrs-perform function)
