DNa replication pt 2

Question 1

what is Chromatin

Answer 1

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.

Question 2

What does a double helix has

Answer 2

• strands connected by h bonds
• polarity
• complementary strands held by h bonds
• anti parallel run in opposite directions

Question 3

Who proved that dna is semi conservative

Answer 3

Meselson and stahl

Question 4

4 steps of dna replication

Answer 4

-unwinding of strands
-initiation of replication
/ elongation if the dna strands being replicated
-termination of replication

Question 5

Where does replication start

Answer 5

• origin of replication
• makes bubbles along chromosomes
• when finish ->two day get dna molecules

Question 6

What is a replication bubble

Answer 6

Two forks for each bubble

- lagging strand gas Okazaki fragments

Question 7

What’s is the replication fork

Answer 7

Parental strands are being unwind and replication of dna takes place

Question 8

What is helicases

Answer 8

Enzymes that untwist the double helix at the replication fork separating the 2 strands and making them available as templates

Question 9

What’s is topoisomerase

Answer 9

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

Question 10

What are single strand binding proteins

Answer 10

Proteins that bind to unpaired dna strands they stabilize then and hold them apart while they serve as templates for complementary dna strands

Question 11

What is primase

Answer 11

A. R a polymerase that hounds dna nucleotides to make the primer using the parental dna strand as a template

Question 12

What is DNA polymerase 3

Answer 12

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

Question 13

What does DNA polymerase 3 need to add nucleotides to a free 3’

Answer 13

Primase

Polymerase 3 the. Adds deoxiribonucleosides to that short primer

Question 14

What is DNA polymerase 1

Answer 14

And enactment that removes and replaces the dna primer

Question 15

What is Ligase

Answer 15

Man enzyme that ligats ends of dna molecules

Question 16

Synthesis of lagging stand functions

Answer 16

Primase - priming for Okazaki fragment
Dna 3 polymerase- elongation of fragment
Poly 3- replacement of ran primer by dna
Ligase - joining of dna strands

Question 17

Synthesis of leading strand

Answer 17

Primase - priming of the leading strand
Dna 3- elongation
Dna 1- replacement if Eva primer by dna
Ligase - joining of dna strands

Question 18

DNA polymerase proofreading

Answer 18

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

Question 19

What is methylation of histones

Answer 19

methyl groups are transferred to amino acids of histone proteins that make up nucleosomes, which the DNA double helix wraps around to form chromosomes.

Question 20

what is Euchromatin

Answer 20

The less condensed form of

eukaryotic chromatin that is available for transcription

Question 21

what is Heterochromatin

Answer 21

chromatin that remains highly
compacted during interphase and is generally no
transcribed

Question 22

central dogma

Answer 22

replication (dna)–trandscription–>mrna (messenger- carries information in genes)–translation–>proteins (acotrs-perform function)