Lecture 10

Question 1

What is the Chargaff discovery?

Answer 1

The discovery that DNA was the genetic material and not proteins. Found out that the amount of T and A was similar (so T must bind with A) and amount of G and C is similar (so G must bind with C)

Question 2

How would describe the structure of DNA?

Answer 2

A double stranded helical molecule with particulate features.

Question 3

What did the X-Ray diffraction pattern of DNA determine about its structure?

Answer 3

• helical
• bases perpendicular to the length of the molecule
• double stranded
• diameter is constant

Question 4

Which nitrogenous bases are purines? What does this mean?

Answer 4

Adenine, Guanine. This means that they are 2 ringed bases.

Question 5

Which nitrogenous bases are pyrimidines? What does this mean?

Answer 5

Cytosine, Thymine, Uracil. This means that they are one ringed bases.

Question 6

What are the components of DNA? What bonds are used to join nucleotides together?

Answer 6

• deoxiribose sugar
• nitrogenous base
• phosphate group
• joined with phosphodiester bonds to form polynucleotides

Question 7

How is the phosphodiester bond formed?

Answer 7

On 3rd carbon, OH reacts with phosphate group attached to 5th carbon on another nucleotide. This uses the enzyme DNA polymerase III.

Question 8

What word is used to describe the DNA strands going in the opposite directions? Why does DNA do this?

Answer 8

Antiparallel, used so can form base pairs.

Question 9

What is the semi conservative model of DNA replication?

Answer 9

• strands pulled apart
• complimentary bases inserted
• splits into 2 DNA, with a parent and new strand