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Proteins – Multipurpose molecules

Proteins, fundamental to life, serve diverse functions including acting as hormones, facilitating movement, supporting the immune system, and catalyzing metabolic reactions through enzymes. Comprised of 20 unique amino acids, the specific sequence and three-dimensional shape of proteins determine their function. Denaturation alters protein shape, hindering their role in biological processes. Understanding proteins is crucial, as they interact with substrates at active sites, enabling biochemical reactions essential for life. This dynamic and versatile nature highlights the importance of proteins in maintaining health and supporting various bodily functions.

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Proteins – Multipurpose molecules

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  1. Proteins – Multipurpose molecules • Function: • many, many functions • Hormones - Regulation • signals from one body system to another • Insulin – blood sugar levels • movement • muscle and skin • immune system - antibodies • protect against germs • enzymes - written over the arrow • help chemical reactions (metabolism)

  2. H | —C— | H C—OH —N— O || H Proteins • Building block = amino acids • 20 different amino acids Carboxyl group (“acid”) Amino group variable group “R” group (20 different ones)

  3. amino acid amino acid amino acid amino acid amino acid Amino acid chains • Proteins – also called polypeptides • amino acids chained into a polymer by peptide bonds • Each amino acid is different – “R group” • some “like” water & dissolve in it • some “fear” water & separate from it

  4. Water-fearing amino acids • Hydrophobic • “water fearing” amino acids • try to get away from water in cell • the protein folds

  5. Water-loving amino acids • Hydrophillic • “water loving” amino acids • try to stay in water in cell • the protein folds

  6. collagen (skin) For proteins: SHAPE matters! • Proteins fold & twist into 3-D shape • that’s what happens in the cell! • Different shapes = different jobs/functions • Shape is determined by the order of the amino acids growthhormone hemoglobin red blood cells carries oxygen pepsin (stomach)

  7. It’s SHAPE that matters! • Proteins do their jobs, because of their 3-D shape • Unfolding a protein destroys its shape • wrong shape = can’t do its job • unfolding proteins = “denature” • temperature (high) • pH (acidity) unfolded“denatured” In Biology, it’s not the size, it’s the SHAPEthat matters! folded

  8. enzyme + enzyme + Nothing works without enzymes! • ALL chemical reactions (metabolism) in living organisms require enzymes to do work (GRRSNERT) • building molecules • Synthesis enzymes • breaking down molecules • digestive enzymes • enzymes speed up reactions • “catalysts” – lower activation energy We can’t live without enzymes!

  9. + enzyme enzyme + Examples • Synthesis Same enzyme for BOTH reactions • Digestion - N

  10. Enzymes are proteins • Each enzyme is the specific helper to a specific reaction • each enzyme needs to be the right 3-D shape for the job • enzymes are named for the reaction they help – usually end in -ase • sucrase breaks down sucrose • proteases breakdown proteins • lipases breakdown lipids • DNA polymerase builds DNA Oh, I get it! They end in -ase

  11. active site Enzymes aren’t used up • Enzymes are not changed by the reaction • used only temporarily - reusable • re-used again for the same reaction with other molecules – written over the arrow • very little enzyme needed to help in many reactions product substrate or reactant enzyme enzyme-substrate complex

  12. Enzyme vocabulary • Enzyme • helper protein molecule • Co-enzyme • Usually a vitamin; NOT protein • Substrate • molecule that enzymes work on • Products • what the enzyme helps produce from the reaction • Active site • part of enzyme that substrate molecule fits into

  13. It’s Shape that Matters!!! The “Key” • Lock & Key model • Shape of protein allows enzyme & substrate to fit together • SHAPE of enzyme for each specific reaction

  14. SHAPE! For enzymes…What matters? • Correct protein determined by: • Correct order of amino acids – • determined by DNA • Temperature • pH (acids & bases) • Substrate Concentration (amount of substrate)

  15. Order of amino acids • Wrong order = wrong shape = can’t do its job! foldedprotein chain ofamino acids DNA right shape! foldedprotein chain ofamino acids wrong shape! DNA

  16. Sickle Cells vs Normal RBC’s

  17. Temperature • Effect on rates of enzyme activity • Optimum (best) temperature • greatest number of collisions between enzyme & substrate • human enzymes • 35°- 40°C (body temp = 37°C) • Raise temperature (boiling) - fever • denature protein = unfold = lose shape • Lower temperature T° • molecules move slower • fewer collisions between enzyme & substrate

  18. 37° Temperature humanenzymes What’s happening here?! Enzyme is denaturing or unfolding reaction rate temperature

  19. pH stomachpepsin intestinestrypsin What’s happening here?! reaction rate 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH acid base neutral

  20. Also Substrate concentration • Lucy and the candy factory http://www.youtube.com/watch?v=4wp3m1vg06Q ALL enzymes are in use; can’t go any faster unless more enzymes are added reaction rate Substrate concentration

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