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DNA & Protein Synthesis Chapter 8

DNA & Protein Synthesis Chapter 8. The Molecule of Heredity. Seeking the Genetic Material. 1928 Griffith finds that virulent bacteria can transform nonvirulent bacteria into the deadly form. Virulent : able to cause disease

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DNA & Protein Synthesis Chapter 8

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  1. DNA & Protein SynthesisChapter 8 The Molecule of Heredity

  2. Seeking the Genetic Material • 1928 Griffith finds that virulent bacteria can transform nonvirulent bacteria into the deadly form. Virulent: able to cause disease • 1944 Avery: found DNA was the molecule of heredity, not protein or RNA. • 1952 Hershey and Chase: found that viruses injected DNA into host bacteria. DNA is confirmed as the unit of heredity. Animation & Game Hershey and Chase Experiment

  3. The Structure of DNA • Structure was discovered by Watson and Crick in 1953, 1962 receive Nobel Prize. • Double Helix: two strands twisted like a winding stair case. • Made up of Nucleotides: Phosphate, Sugar (deoxyribose) and a Nitrogen base (A,T,C,G) (Pg. 185) • Sugar and phosphate molecule are the same for each nucleotide. Nitrogen base changes.

  4. Nitrogen Bases: • Adenine pairs with Thymine • Cytosine pairs with Guanine • Bases are held together by weak hydrogen bonds. • A-T and C-G are called complementary base pairs. • A mistake here is one form of Mutation. • Can you tell me the complementary strand for : AATCGCGA? ______________

  5. How did Watson and Crick find the structure? • With help from fellowscientists such as… • Chargaff:1949 discovered there are always equal amounts of Adenine to Thymine and the same percentage of Cytosine to Guanine. • Wilkins and Franklin: Photographed DNA with X-rays.(pg 187, Fig 10-4) Found helictical shape (i.e. Helix Shape). Chargaff’s Ratios Franklin Click: NOVA News Minute

  6. DNA Replication Pg. 188 • DNA needs enzymes (protein) to copy or replicate itself. • Double helix unwinds using DNA Helicase. • DNA Helicase breaks the hydrogen bonds. • Where the DNA breaks apart is called the replication fork. DNA polymerase (another enzyme) adds nucleotides at this point. Replication Movie HHMI Replication

  7. DNA Replication Hit Large MOV

  8. Here is a great review of DNA and DNA Replication • Please Activate this clip at home and go to the section you are interested in seeing. The Review Button

  9. Checking for errors • DNA Polymerase also proof reads the strands • A mistake in nucleotide pairing is a Mutation • Multiple replication forks happen all at once so that the process is speedy. DNA Review Flashcards

  10. What is RNA and how is it useful? • RNA= Ribonucleic Acid • Transcribes DNA and Translates it into proteins. • Proteins are organic coupounds that have specific jobs in the cell. (Ex. Enzymes) PBS Video RNAi

  11. What are the 3 types of RNA? • mRNA= Messenger RNA • Transcribes or rewrites DNA’s message as mRNA, mRNA carries message to ribosome • rRNA = Ribosomal RNA • Creates the ribosomes on the rough ER and cytoplasm where proteins are made. • tRNA = Transfer RNA • Transfers amino acids to the ribosomes and translates the mRNA into protein. (Called Translation because the message changes from nucleic acid to protein, a different organic compound)

  12. Transcription and TranslationCinema • Don’t relax too much • Pencils out? Notes ready? Lets work! Transcription & Translation Movie Highly detailed And very good Overview Movie Start Here

  13. The Lac Operon • E. coli and the Lac Operon • Only in Prokaryotes • Fig 11-1, 11-2 The Lac Operon, But Not the Operon that Lacks!

  14. How do Eukaryotes control Gene expression? • Transcription creates Pre-mRNA • Pre-mRNA includes Introns and Exons • Introns= Fillers • Exons= Code for proteins • mRNA is just the Exons

  15. What do enhancers do? • Enhancer’s causes the gene it is enhancing to be expressed. Transcription occurs in eukaryotes when an enhancer activates it. Eukaryotic Transcription

  16. Read and review 11-2 • Homeotic genes • Homeobox • Cancer, the types and causes • The war on cancer • Viruses and Cancer • Oncogenes

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