1 / 15

What are chromosomes made of ?

What are chromosomes made of ?. By mass, chromosomes are about half protein and about half DNA If genes are on chromosomes, are they protein or DNA or perhaps a mix?. Basic chemistry of DNA and protein. Proteins : What are the subunits of protein?

may
Download Presentation

What are chromosomes made of ?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. What are chromosomes made of?

  2. By mass, chromosomes are about half protein and about half DNA • If genes are on chromosomes, are they protein or DNA or perhaps a mix?

  3. Basic chemistry of DNA and protein Proteins: • What are the subunits of protein? • How many different types of subunit are there?

  4. General structure of an amino acid

  5. DNA • DNA was discovered in 1869 by Friedrich Miescher, a German Chemist. Extracted from the nucleus. • DNA has subunits. • How many different subunits are there?

  6. The basic structure of DNA and RNA determined by Levene in the 1920’s

  7. General structure of a nucleotide

  8. Levene’s tetranucleotide theory • Logic behind the theory— • Genetic information needs to be complex • More complexity possible in proteins than in DNA—he suggests DNA plays a role as ‘scaffolding’, a repeating sequence of 4 bases • The evidence? Approximately equal amounts of each of the 4 bases found in DNA

  9. Avery, MacLeod and McCarty, 1944 • Assumption: Protein is the genetic material • Plan: if ‘transforming principle’ treated chemically to remove protein, it should lose its power – removed all but 0.02% • Problem: It didn’t

  10. Avery, MacLeod and McCarty, cont. • After chemically removing protein, ‘transforming principle’ still able to convert rough bacteria to smooth bacteria • After treatment with proteinase, ditto • After treatment with RNAase, ditto • After treatment with DNAase –’transforming principle’ activity destroyed • FIRST PAPER SUPPORTING DNA AS GENETIC MATERIAL

  11. Tetra nucleotide theory accepted for nearly 30 years • What finally shifted thought away from protein as the genetic material to DNA as the genetic material? • The ‘transforming principle’ of Griffith, using ‘Rough’ and ‘Smooth’ bacteria in 1928 • Avery, MacLeod and McCarty, 1944stripped away protein without destroying the transforming principle

More Related