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Transcript

  • 1. WARM-UP #7
  • 2. DNA (Deoxyribonucleic Acid)
  • 3. Genetic material of cells…
    • GENES – units of genetic material that CODES FOR A SPECIFIC TRAIT
    • Called NUCLEIC ACIDS
    • DNA is made up of repeating molecules called NUCLEOTIDES
  • 4. DNA Nucleotide O O=P-O O Phosphate Group N Nitrogenous base (A, G, C, or T) CH2 O C 1 C 4 C 3 C 2 5 Sugar (deoxyribose)
  • 5. A HISTORY OF DNA
    • Discovery of the DNA double helix
    • A. Frederick Griffith – Discovers that a factor in diseased bacteria can transform harmless bacteria into deadly bacteria (1928)
    • B. Rosalind Franklin - X-ray photo of DNA.
    • (1952)
    • C. Watson and Crick - described the DNA molecule from Franklin’s X-ray.
    • (1953)
    SEE p. 292-293
  • 6. Watson & Crick proposed…
    • DNA had specific pairing between the nitrogen bases:
    • ADENINE – THYMINE
    • CYTOSINE - GUANINE
    • DNA was made of 2 long stands of nucleotides arranged in a specific way called the “Complementary Rule”
  • 7. DNA Double Helix Nitrogenous Base (A,T,G or C) “ Rungs of ladder” “ Legs of ladder” Phosphate & Sugar Backbone
  • 8. DNA Double Helix P P P O O O 1 2 3 4 5 5 3 3 5 P P P O O O 1 2 3 4 5 5 3 5 3 G C T A
  • 9. Nitrogenous Bases
    • PURINES
    • 1. Adenine (A)
    • 2. Guanine (G)
    • PYRIMIDINES
    • 3. Thymine (T)
    • 4. Cytosine (C)
    T or C A or G
  • 10. Chargaff’s Rule
    • Adenine must pair with Thymine
    • Guanine must pair with Cytosine
    • Their amounts in a given DNA molecule will be about the same .
    G C T A
  • 11. BASE-PAIRINGS C G H-bonds T A
  • 12. Genetic Diversity…
    • Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.
  • 13. The Code of Life…
    • The “code” of the chromosome is the SPECIFIC ORDER that bases occur.
    • A T C G T A T G C G G…
  • 14. DNA is wrapped tightly around histones and coiled tightly to form chromosomes See p. 297
  • 15. DNA Replication
    • DNA must be copied
    • The DNA molecule produces 2 IDENTICAL new complementary strands following the rules of base pairing:
    • A-T, G-C
      • Each strand of the original DNA serves as a template for the new strand See p. 298
  • 16. DNA Replication
    • Semiconservative Model:
    • 1. Watson and Crick showed: the two strands of the parental molecule separate, and each functions as a template for synthesis of a new complementary strand.
    • .
    Parental DNA DNA Template New DNA
  • 17.
      • 1. Why is replication necessary?
      • 2. When does replication occur?
      • 3. Describe how replication works.
      • Use the complementary rule to
      • create the complementary strand:
    A--- ? G--- ? C--- ? T--- ? A--- ? G--- ? A--- ? G--- ? C--- ? A--- ? G--- ? T--- ? Replication Quiz
  • 18.
      • 1. Why is replication necessary?
    • So both new cells will have the correct DNA
      • 2. When does replication occur?
      • During interphase (S phase).
      • 3. Describe how replication works.
      • Enzymes unzip DNA and complementary nucleotides join each original strand.
      • 4. Use the complementary rule to
      • create the complementary strand:
    A--- T G--- C C--- G T--- A A--- T G--- C A--- T G--- C C--- G A--- T G--- C T--- A Replication Quiz
  • 19. (1961) Watson & Crick proposed…
    • … DNA controlled cell function by serving as a template for PROTEIN structure.
    • 3 Nucleotides = a triplet or CODON
    • (which code for a specific AMINO ACID)
    • See p.303
    • AMINO ACIDS are the building blocks of proteins.
  • 20. DNA Transcription
    • DNA can “unzip” itself and RNA nucleotides match up to the DNA strand.
    • Both DNA & RNA are formed from NUCLEOTIDES and are called NUCLEIC acids.
    See p.301
  • 21. DNA Translation
    • The cell uses information from “messenger” RNA to produce proteins
    See p.304-305 We will discuss details of this on a later date
  • 22. Transcription/Translation Quiz
    • Why is transcription necessary?
    • Describe transcription.
    • Why is translation necessary?
    • Describe translation.
    • What are the main differences between DNA and RNA.
    • Using the chart on page 303, identify the amino acids coded for by these codons:
    • UGGCAGUGC
  • 23.
    • 1. Why is transcription necessary?
    • Transcription makes messenger RNA (MRNA) to carry the code for proteins out of the nucleus to the ribosomes in the cytoplasm.
    • 2. Describe transcription.
    • RNA polymerase binds to DNA, separates the strands, then uses one strand as a template to assemble MRNA.
    • 3. Why is translation necessary?
    • Translation assures that the right amino acids are joined together by peptides to form the correct protein.
  • 24.
    • 4. Describe translation.
    • The cell uses information from MRNA to produce proteins.
    • 5. What are the main differences between DNA and RNA.
    • DNA has deoxyribose, RNA has ribose; DNA has 2 strands, RNA has one strand; DNA has thymine, RNA has uracil.
    • Using the chart on page 303, identify the amino acids coded for by these codons: UGGCAGUGC
    • tryptophan-glutamine-cysteine
  • 25. AMAZING DNA FACTS…
    • DNA from a single human cell extends in a single thread for almost 2 meters long!!!
    • It contains information equal to some 600,000 printed pages of 500 words each!!!
    • (a library of about 1,000 books)
  • 26. LET’S REVIEW DNA… LM p.44
    • List the conclusions Griffith & Avery, Hershey & Chase drew from their experiments.
    • Summarize the relationship between genes & DNA.
    • Describe the overall structure of the DNA molecule.
    • What are the 4 kinds of bases?