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Nucleic Acids, Protein Synthesis and Mutations Central Dogma DNA RNA Protein

Nucleic Acids, Protein Synthesis and Mutations Central Dogma DNA RNA Protein. Chapter 12 and 13. Identifying the substance of Genes. Influential Scientists: Griffith - Experimented with mice and bacteria that cause pneumonia and demonstrated TRANSFORMATION .

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Nucleic Acids, Protein Synthesis and Mutations Central Dogma DNA RNA Protein

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  1. Nucleic Acids, Protein Synthesis and MutationsCentral DogmaDNA RNA Protein Chapter 12 and 13

  2. Identifying the substance of Genes • Influential Scientists: • Griffith - Experimented with mice and bacteria that cause pneumonia and demonstrated TRANSFORMATION. - Concluded that some FACTOR (gene) was responsible for the change. • Avery - Followed up on Griffith’s experiment; wanted to know which molecule was important for transformation. • He then extracted the 4 macromolecules from these heat killed cells, all of which were considered to be possible candidates for the carriers of genetic information. • Treated each mixture with enzymes that destroyed the macromolecule and transformation still occurred. • He concluded that DNA is the source of genetic information.

  3. Figure 12–2 Griffith’s Experiment Section 12-1 Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Harmless bacteria (rough colonies) Control(no growth) Heat-killed, disease-causing bacteria (smooth colonies) Disease-causing bacteria (smooth colonies) Dies of pneumonia Dies of pneumonia Lives Lives Live, disease-causingbacteria (smooth colonies)

  4. DNA Phage infectsbacterium Bacteriophage with phosphorus-32 in DNA Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infectsbacterium No radioactivity inside bacterium • Influential Scientists continued: • Hershey and Chase- • Studied viruses– non-living particles that can infect living cells. • Looked at bacteriophages– a virus that infects bacteria. • Supported the conclusion that genes were made of DNA. DNA is the source of genetic information

  5. Where is DNA found? Inside the nucleus DNA is coiled into Chromosomes

  6. Components of DNA • Nucleotide (monomer) • Deoxyribosesugar • Phosphate group • Nitrogen-containing base • Adenine (A) • Guanine (G) • Cytosine (C) • Thymine (T) Purines Pyrimidines

  7. Components of DNA • The structure or shape of DNA = Double Helix = 2 strands • Watson and Crick (1953) – tried to assemble the structure. • Rosalind Franklin (1952) – used a technique known as x-ray diffraction to create a picture. • The x shape indicated DNA is twisted (helix) around two strands.

  8. Components of DNA • Complementary Base Pairing • A↔T, G ↔C (Chargaff’s rule) • Connected by covalent hydrogen bonds DNA with Nucleotides

  9. Takes place in the nucleus (during the S phase) Result: 2 exact copies original DNA DNA Replication (duplication) DNA Polymerase Helicase Replication fork

  10. 1. Helicaseunzips the double helix by breaking the hydrogen bonds forming a replication fork. 2. DNA polymerase adds the complimentary base pairs to each separated strand. DNA Polymerase also “proofreads” each new strand. DNA Replication (duplication) DNA Polymerase Helicase Replication fork

  11. Original: A-T-T-C-C-G Complement: TAAGGC Original: GCTAAG Complement: Original: CTACCA Complement: Original: GACCTA Complement: DNA polymerase proofreads & repairs1error/1Billion DNA Replication, Accuracy & Repair

  12. Nucleotide RiboseSugar Phosphate Group Nitrogen Base Adenine (A) Guanine (G) Cytosine (C) Uracil (U): not T Single Strand 3 Types: Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA) Components of RNA

  13. How to make RNAStep 1 = Transcription: DNA RNATakes place in the nucleus • DNA unwinds. • RNA Polymerase binds to DNA promoter site (begin gene) 3. Add complementary RNA nucleotides (U↔A) Gene Begins RNA Polymerase

  14. Transcription Continued • 4. DNA termination sequencesignals gene end • 5. RNA Polymerase releases DNA & RNA RNA Polymerase RNA Strand DNA Rewinds

  15. TranscriptionDNA makes RNA

  16. 3 Types of RNA 1. 3. Carries instructions from DNA to assemble amino acids into protein. Carries the amino acids to the mRNA at the ribosome. 2. The site where proteins get assembled from mRNA.

  17. How to make Protein = Translation • Involves the decoding of mRNA and assembling a protein • Proteins = polymers = macromolecule • Monomer of protein = amino acid • Polypeptides = sequence of amino acids • Genetic code is read 3 letters at a time. • Codon: every 3 base pairs in mRNA = an amino acid • START Codon: starts translation- 1 codon only AUG • STOP Codon: stops translation- 3 codons  UAA, UAG, UGA • Universal Codon -Amino Acid Code: p. 367

  18. mRNA Codon & Codon Chart • AUG = • Methionine or start codon • AAC = _________ Amino Acids

  19. How to make Protein = Translation • tRNA • In cytosol • Binds specific amino acid to mRNA • Anticodon: • complement to mRNA codons

  20. Translation: mRNA Protein • mRNA leaves nucleus • Ribosome attaches to mRNA start codon • mRNA codon pairs with tRNA anticodon delivering amino acid. • Peptide bond forms between amino acids

  21. Translation: mRNA Protein • mRNA stop codonsignals end of translation. The ribosome releases the newly formed polypeptide. • mRNA released & polypeptide complete

  22. Translation Diagram Polypeptide Chain Peptide Bond Nucleus Amino Acid tRNA Anticodon Codon mRNA Ribosome

  23. Overview DNA RNA Protein Transcription Translation

  24. Mutations • Mutations– are heritable changes in genetic info. • Occurs in only 2 types of cells • Sex-cell (germ-cell) mutations: gametes affect offspring • Somatic mutations: body cells  affect individual • 2 categories of mutations • Gene mutations  produce change in a single gene • Chromosomal mutations  produce change in a whole chromosome.

  25. Gene Mutations A.K.A. Point Mutations (3 types) • Substitution 1 nitrogen base gets substituted by another nitrogen base; this results in a new codon • Sickle Cell Anemia: substitute A for T

  26. Deletion Gene Mutations (con’t) • Nucleotidedeletions & insertions • One base is inserted or removed from the sequence. - Causes Frame-shift mutations • Changes amino acid sequence Insertion Deletion

  27. Chromosomal Mutations (5 types) • Deletion: lose portion  • Duplication: gain extra portion  • Inversion: segment reverses  • Translocation: transfer segment to non-homologous  • Nondisjunction: gamete gets extra or less chromosome (Down Syndrome- Trisomy 21)

  28. Chromosome Mutations Diagrams

  29. Genetic Traits & Disorders • Disorders due to nondisjunction • Nondisjunction: gametes have 1 more or less chromosome (pairs don’t segregate) • Monosomy: 45 chromosomes • Turner’s syndrome: XO • Trisomy: 47 chromosomes • Down Syndrome: trisomy-21 • Kleinfelter’s syndrome: XXY • Patau syndrome: trisomy-13 • Edward’s syndrome: trisomy-18

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