which of the following is correctly matches the
TRANSCRIPT
Which of the following is correctly matches the appropriate monomer and reagent
A. Starch: Triglycerdie & Iodine
B. Protein: Amino Acid & Benedict
C. Simple Carb: Nucleic Acid & Sudan III
D. Complex Carb: Monosaccharide & Iodine
E. Lipid: Triglyceride & Biuret
Enzymes:
“Helper” Protein molecules
Chemical reactions of life
• Processes of life
– building molecules
• Synthesis (anabolic)
– breaking down molecules
• Digestion (catabolic)
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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”
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enzyme
enzymeWe can’t live without enzymes!
Enzymes
• A protein catalyst
• Enzymes are important proteins found in living things.
• $$$An enzyme is a protein that changes the rate of a chemical reaction by lowering activation energy required.$$$
• They speed metabolic reactions.
Enzymes are proteins
• Each enzyme is the specific helper to a specific reaction (specificity)
– 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
Oh, I get it!They end in -ase
Enzymes aren’t used up
• Enzymes are not changed and are not used up 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
enzyme
substrate product
active site
It’s shape that matters!
• Lock & Key model
– shape of protein
allows enzyme &
substrate to fit
– specific enzyme for
each specific
reaction
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Enzyme vocabulary• Enzyme
– helper protein molecule
• Substrate– molecule that enzymes work on
• Enzyme-Substrate Complex– when the enzyme and substrate bind together
momentarily
Enzyme vocabulary• Products
– what the enzyme helps produce from the reaction
• Active site– part of enzyme that substrate molecule fits into
• Activation Energy– Energy required to “activate”/ start a chemical
reaction
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How do enzymes Work?
Enzymes work by weakening bonds which lowers activation energy
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Enzymes
FreeEnergy
Progress of the reaction
Reactants
Products
Free energy of activation
Without Enzyme
With Enzyme
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Enzyme-Substrate ComplexThe substance
(reactant) an enzyme acts on is the substrate
EnzymeSubstrate Joins
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Active Site
• A restricted region of an enzymemolecule which binds to the substrate.
EnzymeSubstrate
Active Site
What affects enzyme action• Correct protein structure
– correct order of amino acids
– why? enzyme has to be right shape
• Temperature
– why? enzyme has to be right shape
• pH (acids & bases)
– why? enzyme has to be right shape
It’s all about that Shape!!!
• DENATURE- Change in shape of proteins
Temperature• Temperature can effect the rate of enzyme activity
– Optimum temperature-
• Temperature at which enzyme works best due to greatest number of collisions between enzyme & substrate
• Example- Human enzymes – 35°- 40°C (body temp = 37°C)
– Raise temperature (boiling)
• denature protein = unfold = lose shape
– Lower temperature T°
• molecules move slower
• fewer collisions between enzyme & substrate
37°
Temperature
temperature
reacti
on
rate
What’s happening here?!
humanenzymes
pH • pH can effect the rates of enzyme activity
– changes in pH changes protein shape~ Denatures
– most human enzymes = pH 6-8
• depends on where in body
• pepsin (stomach) = pH 3
• trypsin (small intestines) = pH 8
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pH
pH
reacti
on
rate
20 1 3 4 5 6 8 9 10
stomach
pepsin
intestines
trypsinWhat’s happening here?!
11 12 13 14
For enzymes…What matters?
SHAPE!