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DNA, RNA And Protein Synthesis

DNA, RNA And Protein Synthesis. Modern Biology Pages 193 - 195. Function of DNA. Structure of DNA must allow the storage and transmission of genetic information. DNA spills from E. coli cell. Modern Biology Pages 193 - 195. Function of DNA. Genetic information must tell

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DNA, RNA And Protein Synthesis

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  1. DNA, RNA And Protein Synthesis

  2. Modern Biology Pages 193 - 195 Function of DNA • Structure of DNA must allow the storage and transmission of genetic information. DNA spills from E. coli cell.

  3. Modern Biology Pages 193 - 195 Function of DNA • Genetic information must tell • cell(s) how to make proteins. Proteins are made in the cytoplasm but DNA remains in nucleus

  4. Modern Biology Pages 193 - 195 Functions of DNA • Proteins form structures and control chemistry of cell. Ribosomes embedded in the E.R. construct proteins

  5. Modern Biology Pages 193 - 195 Functions of DNA • Structure of DNA must allow exact replication to occur.

  6. Why Understanding DNA is Important to You.

  7. Modern Biology Pages 193 - 195 DISCOVERY OF DNA – GRIFFITH’S EXPERIMENT • Called transformation. • Used mice and pneumonia. • Rough (non-virulent) • Smooth (virulent) Griffith’s Experiment

  8. Modern Biology Pages 193 - 195 Avery Determines DNA To Be Hereditary Molecule • Avery, McCloud, and McCarty • Used process of elimination. • Determined DNA was heredity material.

  9. Modern Biology Pages 184 - 187 Important People in DNA Science • Rosalind Franklin of Cal Tech in Los Angeles took pictures using X-Rays in the 1930’s Was never given due credit for her contribution to DNA Science

  10. Modern Biology Pages 184 - 187 Important People in DNA Science • James Watson & Francis Crick discovered structure of DNA in 1953. James Watson Left & Francis Crick right: Nobel prize for DNA structure

  11. Modern Biology Pages 184 - 187 DNA Structure • DNA is a polymer. • The monomer of DNA is called a nucleotide. deoxyribonucleic acid

  12. Modern Biology Pages 184 - 187 Nucleotide Structure • One 5 carbon sugar called deoxyribose. • “Deoxy” = one less oxygen. • “ribo” = than ribose. • Deoxyribonucleic acid • “nucleic” = found in nucleus. • “acid” = acidic Deoxyribose, a pentose sugar, has each carbon numbered.

  13. Modern Biology Pages 184 - 187 Nucleotide Structure Phosphate group attached to the #5 carbon of the sugar. The phosphoric acid is negative and so makes the DNA molecule negative. The deoxyribose has a nitorgenous base and a phoshate attached to it.

  14. Modern Biology Pages 187 - 189 Nucleotide Structure • One nitrogenous base attached to the #1 carbon in the sugar.. • Adenine (Purine) • Guanine (Purine) • Cytosine (Pyrimidine) • Thymine (Pyrimidine) Four bases of DNA

  15. Modern Biology Pages 187 - 189 DNA Structure • DNA molecule has shape of a double helix. • The sides are anti-parallel.

  16. Modern Biology Pages 187 - 189 DNA Structure • Nucleotides linked together form the sides of the DNA molecule. • Phosphodiester bond links phosphates and deoxyribose Each phosphate is linked to two sugar molecules.

  17. Modern Biology Pages 187 - 189 DNA Structure Complementary base pairing rules • Nitrogenous bases form “steps” or rungs of the helix. • Adenine (2 rings) is bonded with Thymine (1 ring) using 2 hydrogen bonds. • Guanine (2 rings) is bonded with Cytosine (1 ring) using 3 hydrogen bonds.

  18. Modern Biology Pages 187 - 189 CENTRAL DOGMA OF DNA DNA mRNA Protein DNA must send a message to ribosomes as to how a protein is to be produced. 2) DNA must replicate itself exactly prior to each cell division.

  19. Modern Biology Pages 187 - 189 Replication of DNA • Replication must: • Occur prior to every cell division. • Occur during “S” phase of interphase. • Result in two identical copies of the DNA molecule.

  20. Modern Biology Pages 187 - 189 Replication of DNA • DNA replication is semi-conservative • Each new molecule is composed of one old and one new strand.

  21. Modern Biology Pages 187 - 189

  22. Modern Biology Pages 187 - 189 Replication Process • Replication fork is where double helix is split apart. • Double helix is split apart by enzyme called DNA Helicase.

  23. Modern Biology Pages 187 - 189 Replication Process • Role of DNA polymerase. • Constructs a new strand of DNA • One side is continuous • One side is discontinuous • Complementary nature of bases allows replication to occur properly. • Replication occurs at many sites at same time.

  24. Modern Biology Pages 187 - 189 Replication Process • Mistakes and repair processes. • Xeroderma Pigmentosa • Lacks proper enzyme to repair DNA damage due to sunlight. • Multiple carcinomas develop due to exposure to uV light

  25. Modern Biology Pages 190 - 194 RNA • Structure of RNA. • Ribose instead of deoxyribose. • Uracil instead of thymine. • Single helix instead of double. • Three types of RNA. • mRNA • tRNA • rRNA RNA is made from DNA

  26. Modern Biology Pages 190 - 194 TRANSCRIPTION • Making mRNA as a messenger. • Process referred to as transcription. • Purpose is to copy the message for a protein from the DNA molecule. Making mRNA

  27. Modern Biology Pages 190 - 194 TRANSCRIPTION • Transcription • DNA untwists and unzips in area of molecule where the message for a certain protein is held. • Role of RNA polymerase. • Role of promoter. • Role of termination signal. Making mRNA

  28. Modern Biology Pages 190 - 194 TRANSCRIPTION • The product of transcription is mRNA, tRNA,and rRNA. • Transcription occurs in the nucleus of the cell.

  29. Modern Biology Pages 190 - 194 Translation • Translation occurs in the cytoplasm. • Amino acids are assembled polypeptides. (Proteins) • Ribosomes assemble polypeptides based on instructions held in the DNA molecule. mRNA leaving the nucleus

  30. Wednesday 1/8/03 Pages 194 - 198 Translation • Protein structure • Composed of building blocks called amino acids. • 20 different types of amino acids. • Sequence and length of amino acid chain determines the characteristics of the protein. Ribosomes attach to the mRNA molecule in the cytoplasm.

  31. Wednesday 1/8/03 Pages 194 - 198 Genetic code • The Genetic Code • Each 3 nucleotides on mRNA is a codon. • Each codon codes for a specific amino acid. • 64 possible codons. • 1 start codons • 3 stop codons • 60 different codons code for 20 different types of amino acids. mRNA codon list

  32. Wednesday 1/8/03 Pages 194 - 198

  33. Wednesday 1/8/03 Pages 194 - 198 Translation • The ribosome binds to the mRNA. • tRNA (with anticodon) brings proper amino acid to ribosome. (met tRNA) • Ribosome moves to next three bases (codon). • Another tRNA brings proper AA to ribosome. • Protein is assembled. • Stop codon signals end of protein. tRNA brings an amino acid to the ribosome.

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