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DNA

DNA. Deoxyribonucleic Acid. Defined : Molecule that stores genetic information Monomer: Nucleotide Millions of nucleotides bond to make nucleic acids Gene: section of DNA that holds instructions to build a protein. Nucleotide Structure. A. T. Three parts Sugar molecule Phosphate group

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DNA

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  1. DNA

  2. Deoxyribonucleic Acid • Defined: Molecule that stores genetic information • Monomer: Nucleotide • Millions of nucleotides bond to make nucleic acids • Gene: section of DNA that holds instructions to build a protein

  3. NucleotideStructure A T • Three parts • Sugar molecule • Phosphate group • Nitrogen base (A, T, C, or G) • Nucleotides combine to make nucleic acids • A pairs with T • C pairs with G G C G C C G T A

  4. How many Nucleotides?

  5. Nucleotides • Sugar (Deoxyribose) connects with the phosphate group • 4 Different Bases: • Adenine (A) • Thymine (T) • Guanine (G) • Cytosine (C) • Chargaff’s Rules: • Rule: amount of A = amount of T • Rule: amount of C = amount of G • Human DNA: ~3 billion pairs C T A A T G T

  6. Double Helix • James Watson and Francis Crick identified DNA’s structure in 1953 • Double Helix: spiral shape of DNA • Nucleotide strands are connected by a hydrogen bond

  7. DNA Replication • Defined: Process of copying DNA • During interphase (S-stage) • Step 1: DNA Helicase “unzips” the two DNA strands (breaks the H bonds) • Step 2: Free floating nucleotides (A, T, C, G) match up • Step 3: DNA Polymerase reconnects the two strands

  8. DNA polymerase Step 1: DNA Helicase “unzips” the two DNA strands (breaks the H bonds) T A A T Both DNA molecules are identical Both DNA molecules contain one original strand and one new strand. This is called the: semiconservative model G C G C A T C G Step 2: Free floating nucleotides (A, T, C, G) match up T A A T G C G C Step 3: DNA Polymerase reconnects the two strands C G T A C G A T DNA Polymerase DNA Helicase

  9. DNA Replication Video Clip

  10. Accuracy & Repair A T T A • Mutation: change in DNA sequence • Mutations can be corrected • Enzyme “proofreads” DNA and check/correct errors • Pre-repair: 1 in 10,000 nucleotides has an error • Post-repair: 1 in 1 billion nucleotides has an error T A C G enzyme A C T C G G C

  11. YouTube: DNA Repair

  12. The Secret of Our Lives:The Human Genome Project

  13. Code For Life: The Human Genome

  14. Review • Name the three parts of a DNA nucleotide. • Name the four nitrogen bases. • List Chargaff’s rules. • Fill in the missing DNA nucleotides: A C ? T ? ? ? G C T ? ? A ? C ? T T ? ? C ? T A T ? ? ? C A ? G ? G ? ? • List what takes place during the three stages of DNA replication. • What type of organic moleules are DNA helicase and DNA polymerase? • Why is DNA replication considered semiconservative? • Where is the DNA mutation? T A G G C C T G T C G A A C A G T A T C C G G A C A A C T T G T C A

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