DNA Structure and Replication Flashcards
Lecture 2
What do chromosomes consist of?
DNA and protein
What are the 3 requirements for genetic material?
- Must allow faithful replication
- Must have informational content
- Must be able to occasionally change
What was the goal of the Griffith experiments of 1928?
Griffith wanted to idenfy this “transforming” substance. So he took two strains of Steptococcus pneumoniae: S-type (smooth) and R-type (rough) and injected them into mice.
What were the results of the Griffith experiments?
live S strain = mice dies
heat-killed S strain = mouse lives
live R strain = mouse lives
heat-killed S strain + live R strain = mouse dies
How were live S strains being recovered in the dead mice?
Transformation, or the transmission of DNA from the S strain to the R strain.
Hershey and Chase wanted to determine what was the genetic material, protein or DNA, how did they do this?
Virus protein and DNA were labeled with radioactivity to determine which is required to replicate virus particles inside host cells. They labeled proteins by using 35 sulfur. They labeled DNA by using 32 phosphorus.
What was the result of Hersey and Chase experiment?
They found that the pellet of bacteria contained the 32 phosphorus, meaning that it was the DNA that was injected from the virus into E. coli.
Cleavage of triphosphate bonds provides ______ for DNA synthesis
energy
What group defines the major chemical differences between RNA and DNA?
2’ -OH group
Purines
double ring structure; A, G
Pyrimidines
single ring structure; C, T, U
A polymer of nucleotides are joined by _’-__’ phosphodiester bonds
5’-3’
Who determined the structure of DNA using x-ray diffraction?
Rosalind Franklin
What bonds N-bases between strands?
hydrogen
Who developed methods to differentially label and separate original DNA strands from newly synthesized strands?
Meselson and Stahl
