Protein Structure & Intro to Protein Synthesis - PowerPoint PPT Presentation

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Protein Structure & Intro to Protein Synthesis

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  1. Protein Structure & Intro to Protein Synthesis

  2. “Magnified” section of protein (unfolded) The “building blocks” are amino acids Recall Enzyme (and protein) structure This is the enzyme “catalase”, the enzyme found in liver

  3. Protein Structure • Amino acids = “Building Blocks” of proteins. • 20 different ones • Each one has • an amino group, • a carboxyl group, • and an “R-group”. • The R-group of each amino acid is unique.

  4. “Amino group”: common to all “Carboxyl group”: common to all “R group”: each is unique

  5. General Structure Specific Examples

  6. Making a protein • A protein is made by linking amino acids together in the correct order (sequence). • Reaction = condensation (aka: dehydration synthesis) reaction. • Many of these reactions occur, over and over, until the protein consists of 100+ amino acids linked together. • http://www2.nl.edu/jste/proteins.htm

  7. Your Turn! • Draw a dipeptide that consists of serine and threonine.

  8. Dipeptide a.a. #1 a.a. #2 Hydrolysis: “Digestion” reaction

  9. Draw it!

  10. http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html

  11. Proteins serve multiple functions in organisms • 5 Examples of Protein Function • Enzymes-protein catalysts • Hormones-protein messengers in bloodstream • Neurotransmitters-protein messengers released by neurons; allow nerve cells to “communicate” • Receptors-membrane bound proteins that bind hormones and neurotransmitters • Transporters- integral membrane proteins act as “tunnels” or bind a substance and move it either in or out of the cell.

  12. Hormones Enzymes Transporters Receptors Neurotransmitters

  13. In all cases, the function of the protein depends on its shape (structure) • Recall: proteins are polymers of amino acids (polypeptides) • Each amino acid has a unique “R-group” that determines its chemical nature. • Amino acids are linked together in long chains by peptide bonds. • The sequence of the a.a. and the interactions of the R-groups cause the polypeptide to fold into a specific shape.

  14. What determines the protein’s shape? • The number of amino acids • The type of amino acids (the R-groups) • The sequence of the amino acids (what order they’re bonded in) • Examples: • Leu-gly-ala-pro • Gly-pro-leu-ala • Result: different shapes

  15. What determines these factors? • Recall: proteins are responsible for the phenotype (appearance) of an organism. • The phenotype is determined by the genotype (genes) • What molecule contains an organism’s genes?

  16. DNA! (The “blueprints”) • Recall: DNA is a double-helix; it consists of 2 nucleotide chains. • The nucleotide chains are made up of nucleotides. These have one of 4 nitrogen bases: ATCG • A gene is a segment of the DNA that has a specific N-base sequence. (A gene is the sequence on one side of the helix.) • The order of the N-bases of a gene determines the order of the amino acids in a protein.

  17. Making a protein • Recall: DNA is in the nucleus (architect’s office) • Proteins are made in the cytoplasm on ribosomes (construction site). • Problem: different locations. There must be a “messenger” that takes the blueprints to the construction site. • This is the job of RNA.

  18. http://www.dnalc.org/view/16017-Francis-Crick-1952.html • http://www.dnalc.org/view/16025-Paul-Zamecnik-1956.html • http://www.dnalc.org/view/16028-Sydney-Brenner-1961.html • http://www.dnalc.org/view/15473-The-Central-Dogma-transcription-and-translation-James-Watson.html