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DNA

DNA. : The Blueprint of Life. deoxyribonucleic acid. I. The History of DNA. A. Avery, Oswald (1944) Discovered that the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next. B. ALFRED HERSHEY & MARTHA CHASE (1952)

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DNA

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  1. DNA : The Blueprint of Life deoxyribonucleic acid

  2. I. The History of DNA A.Avery, Oswald (1944) • Discovered that the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next

  3. B. ALFRED HERSHEY & MARTHA CHASE (1952) • CONCLUDED THAT THE GENETIC MATERIAL OF THE BACTERIOPHAGE WAS DNA, NOT PROTEIN

  4. C.Chargaff, Erwin • discovered a relationship in the nitrogenous bases • ADENINE (A) = THYMINE (T) GUANINE (G) = CYTOSINE (C)

  5. D. Rosalind Franklin (1952) • TOOK AN X-RAY OF THE DNA STRUCTURE SO THE PATTERNS COULD BE SEEN • THE X-RAYS SHOW THAT DNA IS TWISTED AROUND EACH OTHER LIKE A HELIX AND HAS 2 STRANDS

  6. E. Watson and Crick (1953) • STUDIED THE STRUCTURE OF DNA BY BUILDING A 3-D MODEL OF THE MOLECULE AFTER USING CLUES FROM FRANKLIN’S X-RAY OF DNA.

  7. proposed that DNA is made up of 2 chains of nucleotides held together by nitrogenous bases & that the 2 strands are twisted together in a shape called adouble helix.

  8. II. Overview of DNA Nucleus

  9. * Chromosome are made up of super coiled DNA * Histones Base pairs DNA (double helix)

  10. III. DNA Structure and Function A. Description - deoxyribonucleic acid is a polymer made up of repeating monomers of nucleotides

  11. B. Structure 1. Double stranded 2. Helix

  12. 3. Nucleotides - subunits of DNA; 3 parts

  13. *PHOSPHATE group *SUGAR - deoxyribose *nitrogen bases (1of4) Adenine(A) Guanine(G) Cytosine(C) Thymine(T) purines pyrimidines

  14. 4. Complementary Base Pairing A purine is always paired with a pyrimidine. A-T C-G

  15. Location Remains in the nucleus

  16. D. Function - DNA determines an organism’s traits by controlling the manufacturing of proteins. The sequencing of nucleotides forms unique genetic information.

  17. E. Involved with theses processes: 1. Replication - Copying process by which a cell duplicates its DNA 2. Transcription

  18. III. RNA Structure and Function A. Description – ribonucleic acid; similar to DNA (messenger RNA & transfer RNA)

  19. B. Structure 1. Single stranded 2.mRNA – straight line tRNA – t shaped

  20. 3. Made up of subunits called Nucleotides * phosphate group * sugar - ribose * nitrogen base (1of4) - A - G - Uracil (U) - C 4. Base Pairing A-T G-C U-A C-G

  21. Location mRNA – travels from the nucleus to ribosomes tRNA – through sites on the ribosome

  22. D. Function mRNA – carry the genetic information out of the nucleus for protein synthesis tRNA – decode the information by transferring the amino acid to the ribosome

  23. E. Involved with theses processes: 1. Transcription – mRNA is made from DNA 2. Translation – proteins are made from mRNA with the help of tRNA at ribosomes

  24. DNA Base Pairing • TCG AAC TGG • AGC TTG ACC • You try: • CCA GAT TGA GGT CTA ACT

  25. RNA to DNA Base Pairing DNA - TCG AAC TGG RNA - AGC UUG ACC • You try: DNA - CCA GAT TGA RNA - GGU CUA ACU

  26. The Genetic Code

  27. Using the Genetic Code A. Codon – 3 nitrogen bases of mRNA in a row that code for a specific amino acid B. Genetic code – a chart that shows the amino acids that correspond to the codons of mRNA

  28. C. How nucleotides are read – 3 at one time • 1. 3 DNA nucleotides = CAT • 2. 3 mRNA nucleotides = • 3. tRNA nucleotides = GUA CAU

  29. D. Reading the Genetic Code 1. 1st letter (base) of the codon = G 2. 2nd letter (base) of the codon = U 3. 3rd letter (base) of the codon = A Using the genetic code on the front, which amino acid does the above codon produce? ________ Valine

  30. E. To “make” a protein 1. Transcribe the given DNA strand into mRNA 2. Look up the mRNA codons on the Genetic Code table

  31. Practice: AUG UUU CAU ACC CCG UAG Met- Phe- His- Thr- Pro- stop

  32. ACC UGG ACC AGA UCU Serine AAA UUU Lysine ACT ACU Stop

  33. Mutations – changes in the DNA

  34. A. Types of Mutations 1. Chromosomal mutations – involves part or an entire chromosome 2. Point (gene) mutations – rare change in the DNA of genes; usually only 1 nitrogen base

  35. Types of Point Mutations • Base-pair substitutions – one nucleotide is substituted for another • Example -

  36. 3. Frame-shift mutation – when a nitrogen base is inserted or deleted a. Occurs because nucleotides are read 3 at a time (codon) b. NOTE: The earlier the reading frame is shifted, the more likely the resulting protein will be seriously affected • c. Examples – (analogy)

  37. B. Causes of Mutations 1. spontaneously – errors that occur during replication and transcription 2. by a mutagen – an agent that causes a mutation a. examples  radiation – UV, x-rays, nuclear  chemicals – smog, alcohol, tar, cigarette  viruses – insertion of new DNA C. Importance of Mutations – only original source of variation in the gene pool. [creates genetic diversity]

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