Lesson 17: Molecular Basis of Inheritance

From powerpoint

What did T.H. Morgan determine

that genes are located on discrete chromosomes using fruit flies

What are viruses?

very simple structures that consist of DNA surrounded by a protein coat

What did Alfred Hershey and Martha Chase do?

they labeled viral protein coat with radioactive sulfur or DNA with radioactive phosphorus 

• DNA does not contain sulfer

DNA is the genetic material of what?

viruses

True or False: Viruses force cells to make more virus

True

DNA is the ________________ of viruses

genetic material

Percentage of A and T is always _____

Percentage of G and C is always _____

equal

What is Chargaff’s Rule 1?

The base composition of DNA varies between species

What is Chargaff’s Rule 2?

Within a species:

• number (or %) of A and T bases are equal

• number (or %) of G and C bases are equal

What did James Watson and Francis Crick?

elucidated the structure of DNA

What did Rosalind Franklin contribute?

She provided X-ray images that revealed the double helix structure of DNA

Where are the sugar and phosphates located?

Outside of the helix

What did Watson and Crick discover?

hydrogen bonds between the bases and that the two stands were antiparallel

DNA structure - Watson and Crick

Purine + Purine:

too wide

DNA structure - Watson and Crick

Pyrimidine + Pyrimidine:

too narrow

DNA structure - Watson and Crick

Purine + Pyrimidine:

width consistent with X-ray data

A & T form what kind of bond?

2 H-bonds

C & G form what kind of bond?

3 H-bonds