6.1 Experimental Evidence for DNA as the Genetic Material

Question 1

The genetics functions of DNA flow directly from its?

Answer 1

molecular structure

Question 2

What is chemically inert

Answer 2

DNA

Question 3

All the genetic functions of DNA depend on?

Answer 3

Specialised proteins that “read” the information in DNA sequence

Question 4

F.Meischer (1869) do/ discover?

Answer 4

He extracted “nuclein” from nuclei of human white blood cells. A weakly acidic, phosphorus rich material.

Question 5

What did chemical analysis of the nuclein reveal

Answer 5

It revealed that nuclein’s major component was deoxyribonucleic acid (DNA)- It contains deoxyribose(sugar)< found in the nucleus and it is acidic

Question 6

What did staining the cells with Schiff reagent reveal about the location of DNA

Answer 6

Schiff reagent stains DNA red and it revealed that DNA is localized almost exclusively within chromosomes.

Question 7

What are the three elements of the chemical composition of DNA

Answer 7

• Four kinds of nucleotides linked in a long chain:
  1.nitrogenous base: cytosine/guanine/ade-nine/thymine
  2. Phosphate
  3. deoxyribose sugar

Question 8

What are phosphodiester bonds

Answer 8

They are covalent bonds joining adjacent nucleotides

Question 9

What us a polymer

Answer 9

linked chain of subunits

Question 10

true or false: chromosomes contain more DNA than protein

Answer 10

false, they contain more protein than DNA

Question 11

Bacterial transformation implicates DNA as the………..

Answer 11

substance of genes

Question 12

What did F. Griffith (1928) do? also state his dicoveries

Answer 12

He experimented with two strains of Streptococcus pneumoniae(injected into rats). He observed the following:
1. Different in colony morphology and biological activity of the two strains
2. Smooth (S) strain- virulent (wildtype) and causes death
3. Rough (R) strain-nonvirulent (mutation in S form) and doesn’t cause death
4. R cells could be transformed by genetic material transferred from dead (heat-killed)S cells_ making it virulent and deadly (“something” from heat-killed S cells transformed R cells to S cells)
S heat-killed doesn’t cause death
HE IDENTIFIED THAT THERE IS A TRANSFORMING PRINCIPLE

Question 13

Avery, MacLeod, and McCarthy’s experiment (1944)identified that ………

Answer 13

DNA as the transforming principle

Question 14

Whose experiment did Avery and associates use to prove this

Answer 14

Griffith’s experiment

Question 15

Define transformation

Answer 15

The ability of a substance to change the genetic characteristics of an organism.

Question 16

Why was it believed that protein was the genetic material and not DNA

Answer 16

Because DNA is only made up of 4 different subunits and protein is made up of 20 different subunits, they felt DNA is too simple to specify genetic complexity. Also the fact that chromosomes contain more proteins than DNA

Question 17

True or false: Everyone was convinced by Avery’s experiment

Answer 17

false

Question 18

What are bacteriophages?

Answer 18

they are viruses that infect bacteria

Question 19

Why were phages a good candidate for the Hershey-Chase Waring blender experiment

Answer 19

because they contain roughly equal amounts of protein and DNA

Question 20

Which bacteriophage was used for The Hershey-Chase Waring blender experiment

Answer 20

T2