Lecture 21 & 22

Question 1

conservative replication

Answer 1

when the parental stand duplicates, it creates one DNA model with 2 new strands and the 2 original strands stands stay together

Question 2

dispersive replication

Answer 2

parental strands replicates parts of its DNA so the 2 daughter cells are mixtures of old and new

Question 3

semiconservative replication

Answer 3

the 2 strands are taken apart and replicated so each daughter contains one new and old one strand

Question 4

During the Meselson-Stahl experiment, how did they know it wasn’t conservative replication?

Answer 4

The second generation would have DNA with both original strands.

Question 5

Materials for DNA synthesis

Answer 5

• a DNA template
• dNTPs
• primer
• Magnesium
• DNA polymerase

Question 6

dNTPs

Answer 6

deoxynucleoside triphosphate, the substrate of the reaction

Question 7

What side of the template strand is DNA replication started?

Answer 7

Since DNA is antiparallel, it must start on the three prime end of the template, so it can build 5’ to 3’.

Question 8

What is Mg2+ used for?

Answer 8

it stabilizes the negative charge of the deoxynucleotides

Question 9

how does the shape of DNA polymerase help with the synthesis?

Answer 9

only correct base pairs can fit well into the polymers due to steric clash

Question 10

DNA polymerase 1 functions and abilities

Answer 10

proofreading repair, and removes primer to replace with DNA, has both 5’ to 3’ exonucleases.

Question 11

DNA polymerase 3 function and abilities

Answer 11

synthesis DNA, only 3’ to 5’ nuclease

Question 12

Exonuclease

Answer 12

the ability to cleave the ends of the DNA

Question 13

How can both strand be replicated simultaneously?

Answer 13

one strand, called leading is perfectly duplicated 5’ to 3’ into the fork. The other strand, the lagging, a portion is flipped so it too faces the same direction of the leading strand. The portions are called okazaki fragments

Question 14

Origin of replication

Answer 14

a section of the DNA where is it heavy in A-T bonds. it is easy to break because they have weaker bonds.

Question 15

helicase

Answer 15

unwinds the DNA uses ATP

Question 16

primase

Answer 16

a type of RNA polymerase, creates a RNA primer to the DNA polymerase to follow

Question 17

single stranded binding proteins

Answer 17

keeps the DNA from unwinding

Question 18

primosome

Answer 18

primase and helicase together unwinding and putting on primers

Question 19

beta sliding clamp

Answer 19

keeps dna 3 to dan or else it will fall off

Question 20

The order of replication

Answer 20

1) gyrase or topoisomerase - relives the tension
2) helicase - unwinds
3) primase- put on RNA primer
4) single stranded binding proteins - keeps DNA from unwinding
5) DNA pol 3- synthesis the DNA
6) B clamp loader- reloads the DNA pol 3 and secures it with a b clamp
7) DNA pol 1- proof reads and removes primer with DNA
8) DNA ligase - glues the strands together

Question 21

3 subunits of DNA pol 1

Answer 21

-Polyermase - adds DNA 5’ to 3’
- 5’ to 3’ exonuclease- removes RNA primer
- 3’ to 5’ exonuclease- identifies mix match

N- removes primer- proof reads- synthesis- C

Question 22

nick translation

Answer 22

The gap (nick) is usually upstream at the 5’ side because the DNA pol will stop wren it detects a primer. When DNA pol 1 comes to remove and replace, the nick moves downstream because DNA pol 1 will stop after all the primer is removed. The nick is filled by DNA ligase.