Lecture 18: Molecular Basis of Inheritance

Who was Frederick Griffith?

He was studying pneumonia. Pneumonia has two strains smooth and rough strain. The conclusion resulted in a the rough strain could exchange genetic material with the smooth strain. Mixture of heat S killed cells and living R cells. So it suggested that the capsule itself is not the genetic material, but whatever material is being transferred between bacteria probably is.

What is streptococcus pneumoniae?

It is pneumonia. Has rough and smooth strains. The rough strain is not dangerous and has no capsule.The smooth strains has a capsule which makes it more dangerous.

What were the treatments that killed the mouse?

living S cells and the mixture of heat killed S cells and living R cells

What did Avery, McCarty, and MacLeod do?

they identified the transforming agent which was DNA

What did Hershey and Chase do?

They used bacteriophages to see whether protein or DNA was being transferred to bacteria during infection. Conclusion resulted that DNA is the genetic material

Why did they use at radioactive S and P and what did the pellets show?

the radioactive compounds tracked where the mixed phages in the bacteria went. The pellets showed the bacterial cells from radioactive S.

What did Watson and Crick do?

They discovered the double helix structure, sugar phosphate backbone, and bound nucleotides on the inside. Used Franklin and Wilkins X-ray diffraction crystallography

What does “DNA is the genetic material” mean?

That DNA is made up of genes and genes code for heritable traits which are characteristics which can be passed down