What macromolecule carries genetic information?
Agenda for Wednesday April 25th 1.Test stuff2.Intro DNA notes3.Create DNA
Timeline of Identifying Genetic Material
1. Genetic Material Transforms Bacteria - Frederick Griffith, 1931
2. DNA is the hereditary material - Oswald Avery, Colin MacLeod, and Maclyn McCarty, 1944
3. The Genetic Material is DNA - Alfred D. Hershey and Martha Chase, 1952
4. Erwin Chargaff, 1940’s and early 50's5. M.H.F. Wilkins and Rosalind Franklin, early 50’s6. James Watson and Francis H.C. Crick, 1953
Discovery of DNAGriffith• 2 strains of bacteria
– Smooth (pneumonia)– Rough (no pneumonia)
• Conclusion– Disease was passed– One strain was
transformed into the other
Discovery of DNA
Avery• Isolated macromolecules from killed S cells
– DNA, protein, lipids
• Found that living R cells exposed to S strain DNA turned into S cells
• Conclusion– DNA released– R strain incorporated this DNA into its cells
Discovery of DNAHershey and Chase• Bacteriophages – virus that attacks bacteria• Labeled DNA and protein
– Radioactive isotopes– DNA – labeled phosphorous– Proteins – labeled sulfur
• Conclusion– Viruses must inject DNA into living cell– DNA provided info needed to produce new viruses
DNA - Deoxyribose nucleic acid• Store and transmit genetic
information
• Composed of smaller nucleotides
• DNA is an ideal genetic material– store information– able to replicate– undergo changes (mutate)
Structure of DNA
Nucleotides – 3 parts• Deoxyribose sugar • Phosphate group• Nitrogenous base
– A, T, C, G
Nitrogenous Bases• 4 Bases
– Adenine (A), Thymine (T), Cytosine (C), Guanine (G)
• Purine – Double ring– A and G
• Pyrimidine – single ring– T and C
Chargaff’s Rule• Found amount of guanine equals amount of
cytosine– Amount of adenine nearly equals thyamine
• Chargaff’s rule: C=G A=T
Discovering Structure of DNA
X – Ray Diffraction• Maurice Wilkins and Rosalind Franklin• Photo 51• Indicated DNA was a double helix• http://www.pbs.org/wgbh/nova/photo51/
Describe a nucleotide and its parts.
Agenda for Thursday April 26th 1.DNA Extraction Lab2.Finish Notes
James Watson and Francis Crick Double Helix Model
• Used Franklin’s Photo and Chargaff’s dataFeatures of Model**Similar to ladder that is twisted**1. Sides formed by sugar-phosphate backbone2. rungs (or steps) formed by hydrogen bonding
between bases of nucleotides3. bases display complimentary base pairing --
purine always bond to a pyrimidine – A always bonds with T and G always bonds with C
DNA is Complementary
• Complementary: bases on one strand match up with the bases on the other strand – (A-T and G-C)
Example: Strand 1- ATG GGC CTA Strand 2- TAC CCG GAT
Orientation of DNA• The nucleotides form a chain
• The phosphate end of the chain is referred to as the 5' end. The opposite end is the 3' end.
• Q: Since DNA is complementary, what end matches with the 5’ end?
Final Thoughts:DNA
• Similar to a ladder– Rails (outside of ladder)
are deoxyribose and phosphate
– Base pairs are rungs of ladder
– Twisted
Remember
DNA is like an Oreo
Phophates + sugars = cookiesBases = cream filling
Chromosome Structure
• Prokaryotes – DNA in the shape of a ring
• Eukaryotic – chromosomes– 51 – 245 million base pairs
Chromosome Structure
Histones
Nucleosomes
Chromatin Fibers
•DNA wraps around histones•8 histones form nucleosome
Person/People Accomplishment and Description
Year
Remember!!
• 2 strands allow bases to pair– A binds T with 2 H bonds– C binds G with 3 H bonds
Phosphates + sugars on the outside
Bases on the inside (Bases fit like puzzle pieces)
Info on Bases• Purine – double ring base
– Guanine, Adenine
• Pyrimidine – single ring base– Cytosine, Thymine
What is a nucleotide made of (3 parts)?
Agenda for Wednesday May 4th 1.Create DNA
What shape is DNA? How was this discovered?
Agenda for Thursday May 5th 1.Finish Making DNA2.DNA Extraction lab