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Genetics

Genetics. Lesson 4. Central Dogma. DNA RNA Protein. Helicase (unwinds DNA). Ribosome. tRNA. RNA Polymerase. Translation (cytoplasm). Transcription (nucleus). Exons and Introns. mRNA Splicing. RNA polymerase transcribes all of the introns and exons in a gene into mRNA

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Genetics

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  1. Genetics Lesson 4

  2. Central Dogma DNA RNA Protein Helicase (unwinds DNA) Ribosome tRNA RNA Polymerase Translation (cytoplasm) Transcription (nucleus)

  3. Exons and Introns

  4. mRNA Splicing • RNA polymerase transcribes all of the introns and exons in a gene into mRNA • Only the exons code for protein • The spliceosome snips out introns from the mRNA • The remaining exons are assembled into the final mRNA product Exon # 1 2 3 4 5 6 7 8 9 A few possible final mRNA products: Exons 1+2+3+4+5+6+7+8+9 Exons 3+4+5+6+7+8+9 Exons 5+6+7+8+9

  5. Why Does Splicing Matter? • mRNA is translated into proteinby the ribosome and transfer RNAs (tRNAs) • The ribosome holds the mRNA and moves it along so tRNAs that recognize an mRNA codon can add amino acids to the growing polypeptide chain • The mRNA sequence determines the polypeptide chain • A folded poylpeptide chain is called a protein

  6. Amino Acid sequence from mRNA codon sequence (#17-21) • The amino acid sequence determines the structure of a protein • “Structure = Function”

  7. Protein Structure

  8. Why Does This Matter? • All of the cells in your body contain the same DNA* • However, only certain genes are expressed in certain cells • Gene expression = proteins • Certain cells are made of certain proteins • The unique proteins a cell expresses makes the cell unique • A collection of unique cells = a tissue • Tissues include muscle, skin, brain, lung, blood, etc * Disclaimer: there are exceptions to every rule…

  9. Real Life Applications • Medicines can be designed to treat diseases caused by cells expressing specific proteins (such as cancer) • Genes can be altered to correct genetic errors (such as cystic fibrosis) • Genes can be transferred to different organisms (such as bacteria) which can be used to make huge amounts of a desired protein (such as insulin to treat diabetes)

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