DNA The History and Structure of DNA

What does the DNA of all these organisms have in common? They all share a universal genetic code.

History of Heredity Why am I so gorgeous ?

Gregor Mendel Gregor Mendel determined that traits were passed from generation to generation. But, I haven’t figured out how this happens

Frederick Griffith Griffith was working on a vaccine for Streptococcus pneumoniae He worked with 2 strains of the bacteria:  A disease causing a strain which grew in smooth colonies  A harmless grain that grew in rough colonies

Frederick Griffith He added these bacteria strains, some dead and some living, to lab rats. These are his results:

Frederick Griffith Live R+ dead S Bacteria Live Smooth Bacteria Live Rough Bacteria Dead Smooth Bacteria

Griffith Proved: That somehow the dead bacteria have passed their disease-causing substanct to the harmless, living bacteria. We now know this as “transformation”. Griffith discovered that transformation could transform harmless bacteria into disease-causing bacteria

DNA This substance was later determined to be DNA!

Erwin Chargaff Chargoff discovered that DNA has the same amount of adenosine as thymine and the same amount of cytosine as guanine. A = T and G = C AA A A A A A T T T T T T T C CCCC GG G

Rosalind Franklin & Maurice Wilkins Franklin and Wilkins used x-ray to discover that DNA was a double helix. Rosalind Franklin Diffraction X ray DNA

Watson and Crick Watson & Crick won a Nobel Prize for discovering the structural model of DNA. They credited Wilkins and Franklin. Wilkins also got a Nobel Prize but Franklin did not. Franklin had passed away and the Nobels are not awarded posthumously. Watson and Crick

TRY THIS! For each scientist write one word or phrase that describes their contribution to discovering DNA. Griffith- Chargaff- Franklin- Watson and Crick-

lipids carbohydrates Nucleic acids Proteins

DNA is a Nucleic Acid What is a nucleic acid? Nucleic acids are one of the major organic compounds. DNA

DNA Structure What is the monomer for nucleic acids? What is the structure of this monomer? phosphate nucleotide N base PO 4 Sugar PO 4 N base sugar nitrogen base

A NUCLEOTIDE H H2H2 H H H3H3 H H H H H O O O CC C N N P O O O C C C C C O O O C C Phosphate Group 2. 5-Carbon Sugar (Dexoyribose or Ribose) 3. Nitrogen Base 1. Phosphate Group 2. 5-Carbon Sugar (Dexoyribose or Ribose) 3. Nitrogen Base Nucleotides, too

TRY THIS! In your notes, draw a picture of a the monomer of a nucleic acid. Label all 3 parts.

Nucleotides There are four nitrogen bases making up four different nucleotides. Adenine Guanine Thymine Cytosine Pyrimidines Purines A C G T N base

Chargaff’s Base Pair Rules Adenine always bonds with thymine. Adenine (A) to Thymine (T) Guanine always bonds with Cytosine. Guanine (G) to Cytosine (C) The lines between the bases represent hydrogen bonds A C G T

C G A A T G Nucleotide P S N-b Pairing DNA Nucleotides What is a nucleotide? Rule A to C to T G What is the base pairing rule?What would be the complementary nucleotide pairing?

3’End 5’End DNA DOUBLE HELIX ladder shaped molecule

Purpose of DNA Why do we have DNA? DNA contains our genetic information Where is it stored? In the nucleus of a eukaryotic cell. In the nucleoid region of a prokaryotic cell.

TRY THIS! Using the base pairing rules, match up the corresponding bases to this segment of DNA. DNA left strand: ACTTAGGCGTCA DNA right strand: ?

TRY THIS! Answer: DNA left strand: ACTTAGGCGTCA DNA right strand: TGAACCGCAGT