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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)
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Proteins —N— H | —C— C—OH || O Building block = amino acids
20 different amino acids —N— H | —C— C—OH || O Carboxyl group (“acid”) Amino group variable group “R” group (20 different ones)
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Amino acid chains Proteins – also called polypeptides
amino acids chained into a polymer by peptide bonds amino acid Each amino acid is different – “R group” some “like” water & dissolve in it some “fear” water & separate from it
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Water-fearing amino acids
Hydrophobic “water fearing” amino acids try to get away from water in cell the protein folds
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Water-loving amino acids
Hydrophillic “water loving” amino acids try to stay in water in cell the protein folds
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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 growth hormone hemoglobin red blood cells carries oxygen pepsin (stomach) collagen (skin)
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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 SHAPE that matters! folded
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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 enzyme + enzyme We can’t live without enzymes! +
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Same enzyme for BOTH reactions
Examples Synthesis enzyme + Same enzyme for BOTH reactions Digestion - N enzyme +
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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
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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 substrate or reactant product enzyme active site enzyme-substrate complex
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Enzyme vocabulary Enzyme Co-enzyme Substrate Products Active site
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
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It’s Shape that Matters!!!
Lock & Key model Shape of protein allows enzyme & substrate to fit together SHAPE of enzyme for each specific reaction The “Key”
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For enzymes… What matters?
SHAPE! Correct protein determined by: Correct order of amino acids – determined by DNA Temperature pH (acids & bases) Substrate Concentration (amount of substrate)
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Order of amino acids Wrong order = wrong shape = can’t do its job! DNA
folded protein chain of amino acids DNA right shape! folded protein chain of amino acids DNA wrong shape!
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Sickle Cells vs Normal RBC’s
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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
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Enzyme is denaturing or unfolding
Temperature human enzymes What’s happening here?! 37° Enzyme is denaturing or unfolding reaction rate temperature
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pH stomach pepsin intestines trypsin reaction rate pH acid neutral
What’s happening here?! reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH acid neutral base
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Also Substrate concentration
Lucy and the candy factory ALL enzymes are in use; can’t go any faster unless more enzymes are added reaction rate Substrate concentration
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