Final- 16

Question 1

Who discovered the double helix and when

Answer 1

April 1953

Watson and Crick

Question 2

Who preformed the blender experiment

Answer 2

Hershey and Chase

Question 3

What did the blender experiment show

Answer 3

DNA was the genetic material of the phage T2

Question 4

What tagged the protein

Answer 4

Sulfur

Question 5

What tagged the DNA

Answer 5

phosphorus

Question 6

What did Erwin Chargaff do

Answer 6

Developed a series of rules based on a survey of DNA composition in organisms

• composition varies from one species to the next
• Number of A and T is equal to the number of C and G

Question 7

What was published in 1953

Answer 7

a one page paper by Watson and Crick in Nature reporting their double helix model of DNA

Question 8

Where replication begins

Answer 8

Origins of replication

Question 9

What happens when the DNA strands separate

Answer 9

a replication bubble is created

Question 10

What protein unwinds the strands of DNA

Answer 10

Helicase

Question 11

Replication fork

Answer 11

Y shaped region where DNA strands are elongating

Question 12

Single stranded binding proteins

Answer 12

Bind to and stabilize single stranded DNA. Stops DNA from sticking back together

Question 13

Topoisomerase

Answer 13

Corrects overwinding ahead of replication forks by breaking , swiveling and rejoining DNA strands

Question 14

RNA primer

Answer 14

Initial nucleotide strand, starting point for replication (5-10 nucleotides) at 3 prime end

Question 15

Primase

Answer 15

Can start an RNA chain from scratch and adds RNA nucleotides one at a time using parental DNA as a template q

Question 16

DNA polymerase

Answer 16

Add nucleotides to the 3 prime end (catylize the elongation of DNA at the replication fork)

Question 17

What end is DNA added to

Answer 17

3 prime

Question 18

Leading strand

Answer 18

Continuous. Moves towards replication fork

Question 19

Lagging strand

Answer 19

Discontinuous. Moving away from the replication fork

Question 20

Okazaki fragments

Answer 20

Laging strand synthesized as series of fragments `

Question 21

DNA ligase

Answer 21

Joins Okazaki fragments together

Question 22

What do limitations of DNA polymerase cause

Answer 22

No way to complete the 5 prime ends of the daughter DNA strands

Question 23

Why do prokaryotic organisms not have a problem with their DNA stands not being completed at the 5 prime end

Answer 23

They have circular DNA molecules

Question 24

Telomeres

Answer 24

Ends of eukaryotic chromosomal DNA molecules with special nucleotide sequences

Question 25

What happens to the telomeres at each round of replication

Answer 25

They become shorter. They postpone erosion of genes near ends of DNA molecules

Question 26

What have eukaryotic cells evolved to do

Answer 26

restore shortened telomeres in germ cells

Question 27

Telomerase

Answer 27

catalyzes the lengthening of telomeres in eukaryotic germ cells, restoring their original length

Question 28

Describe bacterial DNA

Answer 28

single, circular, double stranded DNA molecule associated with a small amount of protein
Have a dense region of DNA called a nucleoid

Question 29

Describe eukaryotic DNA

Answer 29

single, linear DNA double helix that, in humans, has an average of abaout 1.5x10^8 nucelotide pairs

Question 30

Chromatin

Answer 30

Complex of DNA and protein

fits in nucleus with packaging

Question 31

Heterochromatin

Answer 31

Condensed chromatin

Question 32

Euchromatin

Answer 32

More dispersed chromatin. Interphase

Question 33

What do chemical modifications of histones do

Answer 33

Affect the state of chromatin condensation and affect gene activity