The History and Structure of DNA http://academy.d20.co.edu/kadets/lundberg/images/biology/dna21.gif – DNA image EQ: How is DNA constructed?
They all share a universal genetic code. What does the DNA of all these organisms have in common? The answer – Universal genetic code They all share a universal genetic code.
History of Heredity Why am I so gorgeous?
Gregor Mendel But, I haven’t figured out how this happens Gregor Mendel determined that traits were passed from generation to generation.
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 strain 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 Smooth Bacteria Live Rough Bacteria Dead Smooth Bacteria Live R+ dead S Bacteria
Griffith Proved: That somehow the dead bacteria have passed their disease-causing substance 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! http://academy.d20.co.edu/kadets/lundberg/images/biology/dna21.gif
Erwin Chargaff DNA nucleotides are made up of 4 different nitrogen bases (adenine, thymine, cytosine, guanine) 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 A T C G
Rosalind Franklin & Maurice Wilkins Franklin and Wilkins used x-ray to discover that DNA was a double helix. 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. 1953 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-
Organic Molecules lipids Nucleic acids Proteins carbohydrates
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 sugar nitrogen base N base PO4 Sugar PO4 N base Sugar Deoxyribose
A NUCLEOTIDE 3. Nitrogen Base 1. Phosphate Group 3. Nitrogen Base 2. 5-Carbon Sugar (Dexoyribose or Ribose) 1. Phosphate Group 2. 5-Carbon Sugar (Dexoyribose or Ribose) 1. 2. 3. 3. Nitrogen Base H H2 H3 O C N P 1. 2. 3. Nucleotides, too
TRY THIS! In your notes, draw a picture of a the monomer of a nucleic acid. Label all 3 parts.
Nucleotides A G T C Adenine Purines Guanine Thymine Pyrimidines There are four nitrogen bases making up four different nucleotides. A Adenine Purines Guanine G N base T Thymine Pyrimidines Cytosine C
Chargaff’s Base Pair Rules Adenine always bonds with thymine. Adenine (A) to Thymine (T) A T The lines between the bases represent hydrogen bonds C G Guanine always bonds with Cytosine. Guanine (G) to Cytosine (C)
Pairing DNA Nucleotides What is a nucleotide? What is the base pairing rule? What would be the complementary nucleotide pairing? P N-b Nucleotide S C G Rule A Review slide. Make sure students can pick out the sugar, phosphate group, and nitrogen bases as well as know how the bases pair up (have them tell you the what the answers are before you animate it) A to T A C to G T G
DNA DOUBLE HELIX ladder shaped molecule Anti-parallel structure 3’End
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:TGAATCCGCAGT