chapter sixteen part one

Question 1

1860

Answer 1

Mendel and particulate inheritance
- didn’t know about DNA

Question 2

what was DNA first called when it was discovered?

Answer 2

Nuclein

Question 3

1900

Answer 3

Mendel’s work rediscovered

Question 4

1928

Answer 4

Fred Griffith and the transforming principle

Question 5

Fred Griffith’s experiment

Answer 5

• worked with Streptococcus pneumoniae
• combined heat-killed smooth bacteria with live rough, mouse was dead
• transformation - live R bacteria changed to smooth S bacteria

Question 6

1944

Answer 6

Averty, McCarty, MacLeod
- determined transforming agent DNA
- DNA genetic material for bacteria
- performed extension of Griffith’s experiment

Question 7

Avery, McCarty, and McLeod experiment

Answer 7

had heat-killed S lipids, proteins, DNA, and sugar combined with live R and mice
- only one with DNA died

Question 8

1952

Answer 8

Hershey and Martha Chase
- genetic information for viruses is DNA
- used viruses (bacteriophage) and bacteria
- Waring blender experiment

Question 9

experiment for Hershey and Chase

Answer 9

• used Escherichia coli and virus T2 (bacteriophage)
• labeled proteins with radioactive sulfur, didn’t enter host cells
• labeled DNA with radioactive phosphorus, entered host cells

Question 10

1953

Answer 10

Watson and Crick
- double helix structure of DNA

Question 11

who did Watson and Crick use data from?

Answer 11

• Chargaff
• Wilkins and Franklin

Question 12

Chargaff

Answer 12

ratios of 4 nitrogenous bases
- A = T, C = G
1. DNA base composition varies between species
2. for each species, percentages of A/T bases are roughly equal to G/C

Question 13

Wilkins and Rosalin Franklin

Answer 13

• X-ray crystallography
• could discern diameter of DNA
• even/constant diameter

Question 14

structure resulting from X-ray crystallography

Answer 14

double helix
- negatively-charged phosphate groups faced aqueous surroundings
- hydrophobic nitrogenous bases hidden in interior
- antiparallel

Question 15

why does DNA have an even/constant diameter?

Answer 15

pairing of purine (2 rings) w/ pyrimidine (1 ring)
- A (purine) w/ T (pyrimidine)
- C (pyrimidine) w/ G (purine)

Question 16

how many H-bonds between G/C

Answer 16

3

Question 17

how many H-bonds between A/T

Answer 17

2

Question 18

sides/backbone of DNA composition

Answer 18

sugar w/ 3’ end, phosphate at 5’ end

Question 19

antiparallel

Answer 19

subunits run in opposite directions

Question 20

1958

Answer 20

Meselson and Stahl
- determined semi-conservative DNA replication method

Question 21

3 possible methods of DNA replication

Answer 21

1. conservative
2. semi-conservative
3. dispersive

Question 22

conservative method

Answer 22

parental strands reassociate after serving as template, original helix restored

Question 23

semi-conservative method

Answer 23

2 parental strands separate, each functions as template for synthesis of new, complementary strand

Question 24

dispersive method

Answer 24

all strands of DNA contain mixtures of new/old DNA

Question 25

Meselson and Stahl experiment

Answer 25

• grew E. coli with heavy nitrogen DNA bred with light nitrogen DNA
• first get all heavy, second get all hybrid, third gen 50% hybrid 50% light