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DNA: Deoxyribose Nucleic Acid The Genetic Material. Introduction to DNA (PART 1) Ms. Kim Honors Biology. What does DNA stand for?. D eoxyribo n ucleic a cid. DNA. D eoxyribose n ucleic a cid type of nucleic acid What is the other type of nucleic acid? RNA
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DNA: Deoxyribose Nucleic AcidThe Genetic Material Introduction to DNA (PART 1) Ms. Kim Honors Biology
What does DNA stand for? • Deoxyribonucleic acid
DNA • Deoxyribosenucleic acid type of nucleic acid • What is the other type of nucleic acid? • RNA • DNA function • to hold genetic code • Genetic code = genetic information/instructions for making proteins • DNA is found in nucleus of eukaryotic cells • Found in nucleoid region in prokaryotes
What is DNA made of? • DNA is a macromolecule • Made up of nucleotides • Covalently and hydrogen bonded together • Double stranded • Helix • “Spiral”
What is a nucleotide? • Molecule made of • Deoxyribose sugar • A phosphate group • A nitrogenous base
The Short History of DNA and Genetics (Part 1) • From 1866-1953
Searching for Genetic Material • Gregor Mendel (1866): • discovered that inherited traits are determined by discrete units, or 'genes,’ - passed on from the parents. • Thomas Hunt Morgan (1910): • Discovered genes are located (linked) on chromosomes
Searching for Genetic Material • Fredrick Griffith (1928): • Studied effects of virulent (virus-causing) bacteria vs. nonvirulent bacteria injected into mice • Used transformation: • Inserted foreign DNA and changed protein/ trait • believed that the transforming agent was an inheritance molecule.
Griffith's Transformation Experiment • Used the Pneumococcusbacteria • Include2 types: • a virulent S strain with a Smooth coat • kills mice • a non-virulent R Rough strain • does not kill mice. • Heat destroys the harmfulness of S strain • When heated S is mixed with live R and injected into mice, the mouse dies. • WHY?
Searching for Genetic Material http://brookings.k12.sd.us/biology/ch12DNARNA/Chapter%2012A.mpg
Searching for Genetic Material Oswald Avery, Colin MacLeod, & Maclyn McCarty (1944): • Reported that “transforming agent” in Griffith's experiment was DNA. • Also used the Pneumococcus bacteria and test tubes (NOT mice)
Discovering the Structure of DNA • Edwin Chargaff (1950) • Discovered a 1:1 ratio of adenine to thymine and guanine to cytosine in DNA samples from a variety of organisms. • Noticed that: • # of Adenine = # of Thymine • # of Cytosine = # of Guanine • “Chargaff’s Rule”
Discovering the structure of DNA Chargaff’s Rules A = T C = G C and G are held more tightly together because they are connected by three hydrogen bonds, whereas A and T are held by only two. Chargaff movie and Building Blocks movie http://www.hhmi.org/biointeractive/dna/animations.html
Discovering the structure of DNA Maurice Wilkins (1952) • Studied DNA using x-ray crystallography with another scientist named Rosalind Franklin • He showed Franklin’s x-ray photograph without Franklin’s consent to Watson and Crick, which helped them discover DNA’s structure. • Awarded the 1962 Nobel Prize for Physiology or Medicine with Watson and Crick
Discovering the structure of DNA Photo 51 Rosalind Franklin (1952) • Obtained sharp X-ray diffraction photographs of DNA (Photo 51) • Watson and Crick used her data revealed its helical shape • Watson and Crick went on to win Nobel Prize (1962) for their DNA model
X-rays passing through a helix diffract at angles perpendicular to helix making an "X" pattern, which favors an equal diameter "helix".
She finally gets credit Rosalind Franklin University of Medicine and Science, located on Green Bay Road in North Chicago, Illinois
How was the structure of DNA discovered? • 1953 – Watson and Crick • Wilkins shows Watson and Crick the x-ray pictures from Franklin • This information gave Watson & Crick the evidence to conclude DNA has a helical shape • Made model of DNA which was made up of two chains of nucleotides
Discovering the structure of DNA • James Watson & Francis Crick (1953) • Discovered double helix structure • Solved the three-dimensional structure of the DNA molecule Watson Constructing Bair Pairs movie http://www.hhmi.org/biointeractive/dna/animations.html
DNA Structure (PART 2) Ms. Kim Honors Biology
DNA and Its Structure • From 1953
What is the Double Helix? • Shape of DNA • Looks like a twisted ladder • 2coils are twisted around each other • Double means 2 • Helix means coil
DNA - basics • Deoxyribonucleic Acid • Stores and transmits genetic info • Tells the cells which proteins to make and when to make them • Made up of nucleotides • Phosphate group • Sugar • Nitrogen bases • Double helix structure
The Structure of DNA • Made out of nucleotides • Includes a phosphate group, nitrogenous base and 5-carbon pentose sugar Nucleotide Structure 1 “link” in a DNA chain
A Polynucleotide • MANY nucleotides (“links”) bonded together Nucleotide Structure DNA has a overall negative charge b/c of the PO4-3 (phosphate group)
The Structure of DNA • Backbone = alternating P’s and sugar • Held together by COVALENT bonds (strong) • Inside of DNA molecule = nitrogen base pairs • Held together by HYDROGEN bonds (weaker) Backbone
Phosphodiester Bond • The covalent that holds together the backbone • Found between P & deoxyribose sugar • STRONG!!!
Minor Groove Major Groove
DNA is antiparallel • Antiparallel means that the 1st strand runs in a 5’ 3’ direction and the 2nd 3’ 5’ direction • THEY RUN IN OPPOSITE or ANTIPARALLEL DIRECTIONS • P end is 5’ end (think: “fa” sound) • -OH on deoxyribose sugar is 3’ end • 5’ and 3’ refers to the carbon # on the pentose sugar that P or OH is attached to
Nitrogen Bases (2 types) • Purines (small word, big base) • Adenine • Guanine • Pyrimidines • (big word, small base) • Cytosine • Thymine • Chargaff’s rules • A=T, C=G • Hydrogen Bondsattractions between the stacked pairs; WEAK bonds
DNA Double Helix • http://www.sumanasinc.com/webcontent/animations/content/DNA_structure.html • Watson & Crick said that… • strands are complementary; nucleotides line up on template according to base pair rules (Chargaff’s rules) • A to T and C to G • LET’S PRACTICE… • Complementary strand:5’AATCGCTATAC3’ Template strand: 3’TTAGCGATATG5’