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DNA De-coded: PROTEIN SYNTHESIS

DNA De-coded: PROTEIN SYNTHESIS. Protein Synthesis involves 2 parts : Central Dogma of Molecular Biology : DNA  RNA  Protein 1 2 1. Transcription 2. Translation. Nuclear membrane. DNA. Transcription. mRNA. Ribosome. Translation. Protein. DNA  RNA  Protein.

stewart-velazquez
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DNA De-coded: PROTEIN SYNTHESIS

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  1. DNA De-coded: PROTEIN SYNTHESIS

  2. Protein Synthesisinvolves 2 parts: • Central Dogma of Molecular Biology: DNA  RNAProtein 12 1. Transcription 2. Translation

  3. Nuclear membrane DNA Transcription mRNA Ribosome Translation Protein DNA RNA Protein Eukaryotic Cell

  4. What molecule contains the “code?” • What molecule acts as a “go between?” • What molecule is the end product?

  5. Proteins—why so important? • Structurally: cytoskeleton, flagella, centrioles, histones, etc. • Functionally: enzymes (catalyze all chemical reactions), hormones (FSH), antibodies, movement in muscle cells, cell membrane receptors

  6. Eukaryotic Cell Dilemma • Where is DNA stored? • Where are proteins made? Solution = RNA

  7. Before making proteins, cells must first make RNA • How does RNA(ribonucleic acid) differ from DNA?

  8. RNA differs from DNA 1. RNA has the sugar ribose DNA has deoxyribose 2. RNA contains uracil (U) DNA contains thymine (T) 3. RNA molecule is single-stranded (short) DNA is double-stranded (long) 4. RNA could be mRNA, tRNA, or rRNA DNA is just DNA (the “B” form)

  9. 1.

  10. 2.

  11. 3.

  12. 1. Transcription (OR mRNA synthesis) • mRNA molecules are produced by copying (=Transcription) part of DNA (a gene) into a complementary sequence of nucleotides • This process is started and controlled by an enzyme called RNA polymerase (which also builds 5->3).

  13. DNA RNA Polymerase mRNA 1. Transcription Builds 5  3

  14. Question: • What would be the complementaryRNA strand for the following DNA sequence? • DNA 3’-GCGTATG-5’ RNA_______________

  15. Types of RNA • Three types: A. messenger RNA (mRNA) B. ribosomal RNA (rRNA) C. transfer RNA (tRNA) • Remember: all made innucleus!

  16. mRNA • Carries instructions (a messenger) from DNA to the the ribosome • codes for the specific protein (amino acid sequence) to be made.

  17. start codon A U G G G C U C C A U C G G C G C A U A A codon 1 codon 2 codon 3 codon 4 codon 5 codon 6 codon 7 stop codon peptide bonds of polypeptide (protein) methionine glycine serine isoleucine glycine alanine A. Messenger RNA (mRNA)

  18. rRNA • Part of a ribosome which is like a chromosome (RNA + protein) and Wherethe proteins are made tRNA transfers the parts (amino acids) to make the coded for protein (amino acid sequence) acc. to mRNA codon instructions

  19. B. rRNA in a ribosome

  20. amino acid attachment site one amino acid methionine U A C C. Transfer RNA (tRNA) = complementary sequence to codon anticodon

  21. tRNA

  22. mRNA A U G C U A C U U C G Ribosomes = rRNA + proteins Large subunit P Site A Site Small subunit

  23. Nuclear membrane DNA Transcription Pre-mRNA RNA Processing mRNA Ribosome Translation Protein 2. Translation - making proteins (Fig 12-18) Eukaryotic Cell

  24. 2. Translation = translate nucleotide to amino acid language 1. initiation: start codon (AUG) 2. elongation: add amino acids to polypeptide chain 3. termination: stop codon informs da playas “we done” • Let’s make a PROTEIN!!!!.

  25. aa2 aa1 2-tRNA 1-tRNA G A U U A C 1. Initiation anticodon A U G C U A C U U C G A hydrogen bonds codon mRNA

  26. 3-tRNA G A A Elongation peptide bond aa3 aa1 aa2 1-tRNA 2-tRNA anticodon U A C G A U A U G C U A C U U C G A hydrogen bonds codon mRNA

  27. aa3 3-tRNA G A A 2. ELONGATION aa1 peptide bond aa2 1-tRNA U A C (leaves) 2-tRNA G A U A U G C U A C U U C G A mRNA Ribosomes move over one codon

  28. aa4 4-tRNA G C U peptide bonds aa1 aa2 aa3 2-tRNA 3-tRNA G A U G A A A U G C U A C U U C G A A C U mRNA

  29. aa4 4-tRNA G C U peptide bonds aa1 aa2 aa3 2-tRNA G A U (leaves) 3-tRNA G A A A U G C U A C U U C G A A C U mRNA Ribosomes move over one codon

  30. aa5 5-tRNA U G A peptide bonds aa1 aa2 aa4 aa3 3-tRNA 4-tRNA G A A G C U G C U A C U U C G A A C U mRNA

  31. aa5 5-tRNA U G A peptide bonds aa1 aa2 aa3 aa4 3-tRNA G A A 4-tRNA G C U G C U A C U U C G A A C U mRNA Ribosomes move over one codon

  32. aa5 aa4 3. Termination aa199 aa200 aa3 primary structure of a protein aa2 aa1 terminator or stop codon 200-tRNA A C U C A U G U U U A G mRNA

  33. aa5 aa4 aa3 aa2 aa199 aa1 aa200 End Product • The end products of protein synthesis is the primary structure of a protein. • A sequence of amino acids bonded together by peptide bonds = polypeptide

  34. Examples of some proteins: • Titan: muscle protein up to 33,000 aa • Gastric Acid peptide: 10 amino acids • Hemoglobin: 2 alpha chains (141 aa each) and 2 beta chains (146 aa each) • Lactase (galactosidase in E. coli = 1024 aa long)

  35. mRNA codon chart (p. 303)

  36. Question: The DNA basecode in a gene = T A C Fill in the remaining code and products in the flow of info from DNA to protein. DNA code = T A C mRNA codon = ______ tRNA anti-codon = ______ Amino Acid = ___________ (use de-coder sheet)

  37. Answer: • DNA code = T A C • mRNA codon= A U G • tRNA anti-codon = U A C • Amino Acid = methionine

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