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Enzymes: “Helper” Protein molecules
“Enzyme” music video Enzymes: “Helper” Protein molecules cata – completely ase – enzyme ecto - outside
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Flow of energy through life
Life is built on chemical reactions
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Chemical reactions of life
Processes of life making molecules synthesis breaking down molecules digestion + +
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Nothing works without enzymes!
How important are enzymes? ALL chemical reactions in living organisms require enzymes to work building molecules synthesis enzymes breaking down molecules digestive enzymes enzymes speed up reactions “catalysts” enzyme + enzyme +
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Examples Synthesis (making) enzyme + Digestion (breaking) enzyme +
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How Enzymes Work Enzymes reduce the activation energy! ENERGY TIME
ACTIVATION ENERGY = energy required to cause the reaction to occur. ENERGY TIME ACTIVATION ENERGY = energy required to cause the reaction to occur. Enzymes reduce the activation energy!
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Enzymes are PROTEINS! Each enzyme is the specific helper to a specific reaction each enzyme needs to be the right shape for the job enzymes are named for the reaction they help sucrase breaks down sucrose proteases breakdown proteins lipases breakdown lipids DNA polymerase builds DNA 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 re-used again for the same reaction with other molecules very little enzyme needed to help in many reactions
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Enzyme = reusable protein that can make or break molecules
Substrate = substance to be changed Products = substances produced Enzyme-Substrate Complex = enzyme and molecules temporarily joined Active Site = location on enzyme where substrate fits Is this a digestive or synthesizing enzyme? Enzyme = reusable protein that can make or break molecules
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It’s shape that matters!
Lock & Key model shape of protein allows enzyme & substrate to fit specific enzyme for each specific reaction Substrate Enzyme
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QuickLab: Building an enzyme model.
Virtual Lab 1: Catalase Action by Living Tissue
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HSW/ The Digestive System: Lactose Intolerance
Lactose Intolerant? You need some LACTASE! Lactose = sugar found in milk Lactase = enzyme that breaks down lactose. HSW/ The Digestive System: Lactose Intolerance
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Regulation of Enzymes Correct protein structure Temperature
correct order of amino acids why? enzyme has to be right shape Temperature pH (acids & bases)
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Enzyme Concentration Effect on rates of enzyme activity
increase the amount of enzyme = increases how fast the reaction happens more enzymes = more frequently they collide with substrate
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As concentration increases…
Enzyme concentration Reactions increase… reaction rate As concentration increases… amount of enzyme
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Substrate Concentration
Effect on rates of enzyme activity as increase amount of substrate = increases how fast the reaction happens more substrate = more frequently they collide with enzyme
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Substrate concentration
Reactions increase… reaction rate As concentration increases… amount of substrate
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Temperature Effect on rates of enzyme activity Optimum temperature
greatest number of collisions between enzyme & substrate human enzymes = 35°- 40°C (body temp = 37°C) Too HOT! denature protein = unfold = lose shape Too COLD! molecules move s l o w e r decrease collisions
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How do cold-blooded creatures do it?
Enzymes work within narrow temperature ranges. Ectotherms, like snakes, do not use their metabolism extensively to regulate body temperature. Their body temperature is significantly influenced by environmental temperature. Desert reptiles can experience body temperature fluctuations of ~40°C (that’s a ~100°F span!). What mechanism has evolved to allow their metabolic pathways to continue to function across that wide temperature span?
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pH Affects Enzymes! Effect on rates of enzyme activity
pH changes protein shape most human enzymes = pH 6-8 depends on where in body pepsin (stomach) = pH 3 trypsin (small intestines) = pH 8 buffers adjust pH to keep it normal
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pH stomach pepsin intestines trypsin reaction rate pH 1 2 3 4 5 6 7 8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH
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For enzymes… What matters?
Characteristics of Enzymes For enzymes… What matters? SHAPE!
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TEST TIPS! TEST TIPS! TEST TIPS! When answering a multiple-choice question, be sure to read ALL of the answers before choosing one.
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