Lec 17

Question 1

Friedrich Miescher

Answer 1

First Isolated DNA from white blood cells and called in nucleon

-noted that it was slightly acidic and high in phosphorus

Question 2

Albrecht Kossel

Answer 2

DNA has 4 nitrogenous bases (adenine, guanine, cytosine and thymine)

Question 3

Phoebus Levene

Answer 3

DNA is made of nucleotides

-with each nucleotide having a base sugar and phosphate

Question 4

Purines

Answer 4

Adenine and Guanine

Question 5

Pyrimidine

Answer 5

Cytosine
Thymine
Uracil

Question 6

4 nitrogenous bases of DNA

Answer 6

Adenine, Guanine, cytosine, and thymine

Question 7

4 nitrogenous bases of RNA

Answer 7

Adenine, Guanine, Cytosine, and Uracil

Question 8

Know structure of Purines and Pyrimidines

Answer 8

look in lec. 17

Question 9

Difference between deoxyribose and ribose?

Answer 9

Deoxyribose is missing the oxygen on the 2’ Carbon

Question 10

Nucleoside

Answer 10

sugar+base

Question 11

Nucleotide

Answer 11

Sugar + base + phosphate

Question 12

nucleoside monophosphate

Answer 12

is another name for nucleotide

Question 13

nucleotide triphosphate

Answer 13

sugar + base + 3 phosphates

Question 14

Who proposed the tetra nucleotide structure of DNA? and what was the genetic material thought to be back then?

Answer 14

Phoebus Levene and the genetic material was thought to be protein

Question 15

Griffeth

Answer 15

OBSERVED Transformation

• cells did not need to be injected into a mouse in order to get transformation. Transformation could occur if heat-killed smooth cells were mixed in a test tube with non virulent cells
• transformation can be accomplished by incubating the filtrate from heat killed cells with nonvirulent cells showing that intact virulent cells were not required for transformation.

**heat-killed S-cells do not cause death

Question 16

Avery, MacLeod and McCarty

Answer 16

DNA is the “transforming principle”

Question 17

Hershey and Chase

Answer 17

Showed that DNA holds the genetic information, not protein, through their experiment of following the tract of protein and DNA in phages through isotopes.

Question 18

Yanofsky

Answer 18

Studied Tryptophan synthetase genes and proteins

-established that changes in DNA and protein were collinear

Question 19

Heinz Äraenkel-Conrat and Bea Singer

Answer 19

looked at two strains to determine if genetic material was RNA or protein. Virus particles were type A which was RNA

THUS proved RNA was the genetic material in RNA virus

Question 20

Maurice Wilkins and Rosalind Franklin

Answer 20

X-ray Diffraction Studies

-results in famous picture of DNA and showed that DNA was a Helix

Question 21

Erwin Chargraff

Answer 21

Base composition studies

Concluded:
1 A=T and G=C
2 A+G=T+C from (A+G)/(T+C)=1

Question 22

Watson and Crick

Answer 22

Model for DNA structure (determined the structure)
-base paring between two strands of nucleotides allows for content width of helix and agrees with charges base composition rules

Question 23

Phosphodiester bonds

Answer 23

join sugar-phosphate backbone

Question 24

Is DNA positive or negatively charged?

Answer 24

negative

Question 25

What nucleotides are complementary to each other in DNA?

Answer 25

A-T

G-C

Question 26

How many hydrogen bonds are between a Adenine and Thymine?

Answer 26

2 hydrogen bonds

Question 27

Hydrogen bonds

Answer 27

are relatively weak attractions between positively and negatively charge molecules. They are NOT the main force joining the two strands of DNA

Question 28

How many hydrogen bonds are between Guanine and Cytosine?

Answer 28

3 hydrogen bonds

Question 29

Plectonic coil?

Answer 29

Needs to unwind to separate the two strands

Question 30

What is the main force in stabilizing the double helix?

Answer 30

Hydrophobic interactions (maximized by base stacking)

Question 31

Where are the hydrophobic bases located on the double helix?

Answer 31

in the center

Question 32

Where is the hydrophilic backbone located on the helix?

Answer 32

on the outside