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Why Do We Need Proteins?

Why Do We Need Proteins?. Cell Structure Cell = 80% protein . Cell membrane. Why Do We Need Proteins?. Cell Processes Hormones (signals) Enzymes (speed up reactions). Why Do We Need Proteins?. Membrane Channels (remember transport?) Neurotransmitters (carry nerve/brain messages).

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Why Do We Need Proteins?

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  1. Why Do We Need Proteins? • Cell Structure • Cell = 80% protein Cell membrane

  2. Why Do We Need Proteins? • Cell Processes • Hormones (signals) • Enzymes (speed up reactions)

  3. Why Do We Need Proteins? • Membrane Channels (remember transport?) • Neurotransmitters (carry nerve/brain messages)

  4. What Do We Need For Protein Synthesis? 1.DNA • Template for making mRNA during Transcription

  5. What Do We Need For Protein Synthesis? 2. RNA • mRNA = (messenger RNA) makes and takes copy of DNA to cytoplasm • tRNA = (transfer RNA) Matches w/ mRNA on ribosome and carries AA to add to protein chain

  6. What Do We Need For Protein Synthesis? 3. Ribosome Reads mRNA Directs tRNA Creates peptide bonds between AAs (makes polypeptide chain)

  7. What Do We Need For Protein Synthesis? 4. Amino Acids (AAs) • Building blocks of proteins (20 AAs exist) • Protein = AA chain = polypeptide chain • ORDER MATTERS! AA order determines function of protein

  8. Steps of Protein Synthesis • Transcription (writing the “message”) DNAmRNA messenger carries code to cytoplasm • Translation (reading the “message”) mRNA tRNA protein (AA chain) message translated into a protein

  9. Steps of Protein Synthesis (Nucleus) (Cytoplasm)

  10. Transcription DNA to mRNA • Location = nucleus • Steps a. Enzyme binds to DNA, unzips it b. mRNA copy of gene made from DNA template *U replaces T in RNA

  11. Transcription 3 DNA nucleotides (triplet) to mRNA codon Codons

  12. Translation mRNA to tRNA to protein (AA chain) Location = cytoplasm (first codon in mRNA is the start codon)

  13. Translation Steps of Translation 1. mRNA moves to cytoplasm, binds to ribosome 2. tRNA anticodon UAC brings AA (methionine) to mRNA codonon ribosome

  14. Translation 3. Ribosome moves down mRNA to next codon 4. tRNA anticodon brings & attaches next AA with peptide bond

  15. Translation 5. tRNA leaves ribosome once AA attached Protein chain AA tRNA mRNA

  16. Translation 6. Steps 1-5 repeated, adding AAs until STOP CODONsignals end of protein 7. Polypeptide chain released from ribosome

  17. Synthesis Practice DNA (triplet) mRNA (codon) tRNA (anti-codon) TAC AUG UAC GGA CCU GGA CCT GGA CCU TAT AUA UAU AGA UCU AGA ACT UGA ACU

  18. DNA (triplet) mRNA (codon) tRNA (anti-codon) TAC AUG UAC GGA CCU GGA CCT GGA CCU TAT AUA UAU AGA UCU AGA ACT UGA ACU Synthesis Practice Amino Acid Met (Start) Methionine Pro Proline Gly Glycine Ile Isoleucine Ser Serine Stop

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