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Central Dogma of Biology: Protein Synthesis

Central Dogma of Biology: Protein Synthesis. Permanent set of genes (ATCG sequences). DNA. Transcription (nucleus). DNA transfers code to mRNA. mRNA. Disposable copies of protein code. Translation (cytoplasm). mRNA, tRNA and rRNA produces protein. Protein.

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Central Dogma of Biology: Protein Synthesis

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  1. Central Dogma of Biology:Protein Synthesis Permanent set of genes (ATCG sequences) DNA Transcription (nucleus) DNA transfers code to mRNA mRNA Disposable copies of protein code. Translation (cytoplasm) mRNA, tRNA and rRNA produces protein Protein Genes expressed in cells as protein

  2. RNA Type & Structure • Single strand • Uracil (U): • replaces thymine (T) • Types: • 1.Ribosomal (rRNA): • rRNA +proteins = ribosome • Messenger (mRNA): • Message DNA  ribosomes • 3.Transfer (tRNA): • Amino acids  ribosomes Page 240 Figure 14.3

  3. Triplet Code Codon: 3 nucleotides (CGA) = 1 codon = 1 amino acid (arginine) Code for each amino acid • Universal: same code all organisms = “unity of life”. • Degenerate: most amino acids > 1 codon protects against mutations • Unambiguous: 1 code 1 meaning • Read 3 letters at a time. Letters THEFOXATETHEHOTDOGreads: THE FOX ATE THE HOT DOG

  4. Triplet Code: • 43 = 4 bases (A, T, C, G) • = (4x4x4) = 64 codes • = 61 amino acid codes • + 3 stop codes = 64 • AUG= start code • 3 stop codes: • UAA, UGA and • UAG Page 241 Figure 14.5

  5. Transcription (nucleus) • mRNA Synthesis: • Complementary to portion of 1 • DNA strand - template • Promoter: • Starting point and direction • 2.RNA polymerase: • Bonds nucleotides together • 3.Elongation: • Stops at terminator sequence. Page 242 Figure 14.6

  6. Transcription: mRNA Synthesis 1. DNA is template primary mRNAformed 2. Primary mRNA: cap (guanine) and poly-A tail (adenine) aids exit nucleus prevents enzyme degradation exon = expressed DNA intron = DNA not expressed 3. mRNA splicing: introns removed 4. mRNA leaves nucleus through nuclear pore. Page 243 Figure 14.8

  7. Transcription Summary DNA template  mRNA • DNA helix unzipped • mRNA nucleotides pair with DNA • U replaces T • Begins at promoter • RNA polymerase bonds nucleotides • Stops at terminator • Releases mRNA • Cap and poly-A tail added • Introns removed • mRNA leaves nucleus

  8. Translation (cytoplasm) Summary 1. Initiation • mRNA combines with ribosome. • tRNA bonds methionine to AUG start code 2.Elongation • Methionine tRNA at “P” site • Peptide at “P” • Amino acid arrives at “A” • tRNA site sequence “A”  “P”  “E”  released 3.Termination • Ends at stop code • Release factor frees protein

  9. Page 248 Figure 14.14 5’ AUGUAUUAUACUACUAG 3’mRNA Start Stop

  10. Genetic Mutations Point Mutations: • nucleotide change = codon change = amino acid change CCU = proline CGU = arginine • Sickle Cell • Replication errors at 1/100,000 • Proofreading corrects errors – not 1/1billion • DNA damage repaired by enzymes (p53) Frameshift Mutations: • nucleotides inserted or deleted • THE-----CAT-----ATE-----THE----- RAT • Delete C and shift sequence: • THE----- ATA-----TET-----HER----- AT_ Genetic mutations can be beneficial  raw material for evolution.

  11. Causes of Gene Mutations Spontaneous Replication Errors: Environmental:Carcinogens: Transposons or “jumping genes” DNA sequence moves within and between chromosomes. Bio 105 lab. Page 260 Figures 15b and 15c

  12. Biotechnology, Genetic Engineering, Cloning 1970’s legislation on “genetic engineering”. Gene Therapy: arthritis, aids, hemophilia Cloning Plants: Cloning Animals: frogs, carp, sheep, rhesus, monkey, pig, gaur, cattle, cat, fly, mice, rabbit, mule, deer, horse, rat Presidential Elections 2003 regulation of “stem cell” research “Jurassic Park” “animal actors”

  13. Biotechnology Manipulation of DNA within and between organisms Gene Revolution:Insert genes to improve food supply. Genetic engineering:Insert alien gene into crop plants. Bt = Bacillus thuringiensis RR= Agrobacterium CP4 Genetically Modified Organism (GMO) Crop plant with the alien gene.

  14. Biotechnology: Genes for Medicine Pharmaceuticals • Create medicine in plants • High Blood Pressure • Heart Disease • Vitamin A in rice • Iron Deficiency • “fishy” omega-3

  15. Identifying the Gene DNA Fingerprinting: (CSI) • Cut DNA with restriction enzymes  fragments. • Gel Electrophoresis: • Gel (Jell-O like) • Electric current • Separates the fragments by size. • Cut out the gene

  16. Biochemical Genotypes and Phenotypes F1 generation will be all Aa and F2 generation will be 1:2:1 ratio

  17. Creating Transgenic Plants, Animals, Bacteria • Cut human and bacteria DNA with enzyme. • Restriction Enzyme: make specific double strand cuts. • Put DNA fragments in test tube. • Enzyme seals fragments together. • Look for bacterial DNA with human gene Page 268

  18. Biotechnology: Animal &Bacteria Genes Bacteria • Insert genes in bacteria • Plasmid: • Circular piece of DNA • rDNA: recombinant DNA • Uses • Extract copper • Digest crude oil • Synthetic Insulin Original from cows Animals • Milk, eggs, meat, etc. Page 268 Figure 16.1

  19. Cloning Procedures in Animals Therapeutic Cloning (SCNT): somatic cell nuclear transfer correct medical problem. Reproductive Cloning: create new individual

  20. Transgenic Animals: Animal with gene from another organism. Problem: Need to turn genes on or off for development. Dolly the transgenic sheep (1997). Dolly was born old. Transgenic goat milk  antithrombin that inhibits blood clots marketed as “ATsyn”. 1. Creating transgenic goat. Page 271 Figure 16.5 2. Creating cloned goats

  21. Stem Cell Human Research Example Use of discarded umbilical cords. • Recover umbilical cord blood. • Check for infectious agents and identify tissue type. • Remove red blood cells and freeze in liquid nitrogen. • Thaw, wash and inject into patient, or insert gene or use in research.

  22. Stem Cells in Humans Stem Cells: Undifferentiated primordial cells. Copy themselves. Develop into any cell type = IMMORTAL • Zygote:best stem cell. • Embryonic stem cells:cells needed for • development (blastula inner cells). • Adult stem cells:cells for repair and • regeneration (skin, blood, gut) • Female stem cells better at regenerating • muscle cells than men. • Types: • Totipotent • Pluripotent • Multipotent

  23. Stem Cell Research – Medical Breakthrough? Stem Cell Types: • Totipotent:total potentialof organism =zygote. • Pluripotent:give rise any cell type, except those needed to development a fetus =inner cells of blastula. • Multipotent:give rise to multiple cell type =fetal tissue and adult cells. Muscle cells Bone cells Nerve cells Stem Cells

  24. Totipotent Stem Cells Totipotent: • Give rise to any cell of 200 body cells = zygote • Inner cells of the blastula. • Donated by fertilization clinics • Extract before 150 cells (day 4). • Issue: Chemicals to turn the correct genes on or off.

  25. Pluripotent Stem Cells Pluripotent (day 18): • Give rise to gastrula: • Ectoderm: • Endoderm: Mesoderm: • Can’t develop fetus. Issue: Lower potential to turn correct genes on oroff.

  26. Multipotent Stem Cells Multipotent (adult): • Reproduce daily  produce specific cells (blood, bone marrow). • Adults, children and umbilical cord. Issues: • Mutation is a problem. • Limited potential. • Turn genes off and on. Advances: • Spinal chordpatch (2004) • Made red blood cells (2008)

  27. Therapeutic Cloning (SCNT) Extract Nucleus 2n 1n Extract Nucleus Skin Cell Egg Cell Discard Cell 1n Inject Skin Cell Nucleus 2n Blastocyst Day 4-5 2n Culture Inner Cell Mass (ICM) 2n Bone Blood Muscle Nerves Liver

  28. Stem Cell Research: Creating a Human How can we create a human embryo? • Sexual: egg + sperm  zygote • Cloning or asexual – stem cells • Parthenogenesis – unfertilized egg Problem: some of genes needed for embryo development only activated in sperm chromosomes. If a man clones himself, is the clone his son, brother, twin brother, identical twin, uncle or father? Insert 2n nucleus egg 2n cloned zygote Remove 1n egg nucleus. Cloned Embryo Cloned Baby Stimulate Cell 1n egg + 1n polar body Egg behaves as 2n Electric Shock Zygote Embryo

  29. Embryo Selection and Designer Babies Ethical? For what purpose? X X X Implant selected zygote into female and carry to term . X X X X X X X Test for the trait you want. Fertilized Eggs Would you go to the human library of genes and select the phenotype of your child?

  30. Designer Babies (not cloning) in Humans Add additional traits by use of vectors. Pick your egg and sperm. Egg Zygote Insert Genes Grow Embryos Sperm Petri Dish Ethics???? What about other embryos? Fingerprint Embryos Review baby characteristics. Human Genome Project Select Desired Embryo Implant in female. Select desired baby.

  31. 23 and Me DNA analysis company $1,000 550,000 markers Search on what segment relates to what Combine all client data Relate phenotype to DNA segment

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