DNA replication

Question 1

who am I:
I showed the heredity of traits (at the time the molecule that transmits the hereditary information was not known)

Answer 1

Mendel

Question 2

who am I:
I discovered DNA

Answer 2

Friedrich Miescher

Question 3

who am I:
I discovered transformation

Answer 3

Frederick Griffith

Question 4

what is transformation?

Answer 4

-traits can be passed down from dead bacteria to the live non-pathogenic bacteria
-must be due to passing of molecules between dead and live cells

Question 5

who are we:
discovered the hereditary molecule

Answer 5

macleod, avery, and mccarthy

Question 6

who are we:
we used bacteriophages to prove that DNA is the hereditary molecule

Answer 6

hershey and chase

Question 7

who am I:
I found the matching proportion of nucleotides

Answer 7

erwin chargaff

Question 8

who are we:
we developed the first molecular model of DNA

Answer 8

watson and crick

Question 9

how many hydrogen bonds does guanine make with cytosine?

Answer 9

3

Question 10

which model am I:
-one strand of the parental duplex remains intacts in daughter strands
-in the first replication, a new complementary strands is built from each parental strands, hence creating DNA with new and old strands
-in the second replication, there is an entire new DNA molecule and one DNA molecule with old and new strands

Answer 10

semi-conservative model

Question 11

which model am I:
-both strands of the parental duplex would remain intact and a new DNA copy would consist of all new DNA strands
-in the first replication, both parental strands are being replicated, thus creating a new pair of DNA strands
-in the second replication, there will be 2 new DNA duplex (on one side) and one new + one old DNA duplex on the other

Answer 11

conservative model

Question 12

which model am I:
-in this model, copies of DNA consist of mixtures of parental and newly synthesized strands (i.e. the new DNA would be dispersed throughout each strand of both daughter strands after replication)

Answer 12

dispersive model

Question 13

which replication model is the correct one?

Answer 13

semi-conservative model

Question 14

which experiment helped determine which replication model is accurate?

Answer 14

Meselson and Stahl experiment

Question 15

describe the Meselson and Stahl experiment

Answer 15

-bacteria are grown in heavy nitrogen medium (isotope)
-bacteria will incorporate heavy nitrogen in their DNA
-then some of the DNA was extracted and purified (density gradient centrifugation)
-bacteria were transferred to a lighter nitrogen media
-after one DNA replication, light nitrogen will be in bacteria DNA

Question 16

where does DNA replication start?

Answer 16

origin of replication (only one in Prokaryotes)

Question 17

why is the origin of replication a region rich in A-T?

Answer 17

because it is easier to melt since there are only 2 hydrogen bonds between A-T

Question 18

How does DNA replication start in Prokaryotes?

Answer 18

DNAa protein activates initiation of DNA replication by separating the 2 DNA strands

Question 19

does DNA replication (in prokaryotes) occur in a bidirectional manner?

Answer 19

yes

Question 20

which enzyme adds nucleotides to the free 3’ end of a growing DNA strand?

Answer 20

DNA polymerase

Question 21

what are the 3 things necessary for DNA replication?

Answer 21

-a template strand
-nucleoside triphosphate (nucleotide)
-replisome

Question 22

which enzyme am I:
-untwists the double helix at the replication fork, separating the 2 strands and making them available as template strands
-this requires energy

Answer 22

helicase

Question 23

what am I:
-binds to the unpaired bases of the DNA strands, stabilizing them until they serve as templates for the synthesis of new complementary strands

Answer 23

Single-strand binding protein (SSB)

Question 24

which enzyme am I:
-topoisomerase enzyme that cuts and untwists the ahead of the replication fork to relieve the strain caused by the helicase

Answer 24

DNA gyrase

Question 25

what am I: complex molecular machine that carries out replication of DNA

Answer 25

replisomes

Question 26

what are we: -small pieces of RNA that is complementary to the DNA template strand -synthesized by primase (type of RNA polymerase)

Answer 26

primers

Question 27

what am I: synthesize a complementary DNA strand from 5' to 3' using the template DNA strand as reference

Answer 27

DNA polymerase III

Question 28

what am I: replace the RNA nucleotides of the primers with DNA versions, adding them one by one onto the 3' end of the adjacent Okazaki fragment

Answer 28

DNA polymerase I

Question 29

what am I: forms a phosphodiester bond between the 2 okazaki fragment

Answer 29

DNA ligase

Question 30

which type of ability am I: serves as a proofreading function because it allows the enzyme to back-up and remove a mis-paired base

Answer 30

3'-5' exonuclease activity

Question 31

Is the synthesis of DNA is done at the same time on the leading and lagging strands?

Answer 31

yes

Question 32

which strand does DNA polymerase epsilon take care of?

Answer 32

leading strand

Question 33

which strand does DNA polymerase delta take care of?

Answer 33

lagging strand

Question 34

what is the role of the PCNA sliding clamp?

Answer 34

attaches the enzyme complex to the DNA

Question 35

what are the differences between Prokaryotes and Eukaryotes when it comes to DNA replication?

Answer 35

-Eukaryotes have a larger amount of DNA organized into multiple chromosomes -eukaryotes have linear chromosomes

Question 36

where can replication bubbles be found?

Answer 36

around the origins of replication

Question 37

does the replication of DNA occur in both directions in Eukaryotes?

Answer 37

yes

Question 38

what is the "problem" in DNA replication with Eukaryotes and how does it occur?

Answer 38

-chromosomes get shorter after each DNA replication -when the last primer is removed there is no 3' end to replicate the DNA using polymerase I

Question 39

what am I: a region of non-coding nucleotide sequences at each end of a chromosome, which protects the coding portion of the chromosome

Answer 39

telomere

Question 40

what does telomerase do?

Answer 40

-extends the telomeres of chromosomes -adds nucleotides to the overhanging strand fo the telomere -not usually active in most somatic cells