U3: Digestion & Enzymes Flashcards
Activation energy
Energy needed to weaken/contort bonds of reactants so bonds can break and new bonds can form
energy that “activates the reactants”
Induced fit
Enzymes are flexible and form to the shape of the substrate when the substrate enters the active site.
Flexibility allows the enzyme to squeeze the substrate to help break bonds to form products
Substrate
The reactant that an enzyme works on
Enzymes hold in place by interactions like H-bonds or ionic bonds
Where the reaction occurs in an enzyme
Active site
Enzymes
Increase rate of reaction (Catalysts)
Reusable
SOME end in -ase and are named after their substrate
Substrate specific
proteins, made of amino acids
How do Enzymes increase reaction rate?
lower the activation energy needed:
- helps bond in substrate change shape into unstable high-energy state which the reaction can proceed from
- can put pressure on bonds needed to break
- can position substrate in a beneficial way
Process of an Enzyme working
- Enzyme in a relaxed position, active site ready to be occupied
- Substrate(s) enter active site, enzyme shifts position to hold more snugly
- Substrate(s) converted into product(s) through hydrolysis or dehydration synthesis
- Product(s) are released and the enzyme returns to its initial position
(5. reaction is repeated – return to step one)
Explain why enzymes denature
Enzymes work best in specific environmental conditions. If they are not within these conditions, they become denatured - they “relax” in shape so the active site is altered or lost and they don’t work.
A denatured enzyme can work again if returned to its suitable environment.
Factors that can cause denaturing: temperature, pH
Affect of temperature on enzyme function
Colder atoms move slower so the reaction will occur slower — I might be forgetting a point here need to ask someone
A too hot environment will start to denature enzymes due how their bonds function
Graph: Rate of reaction increases to point which is optimal environment, then decrease
Affect of pH on enzyme function
There will be enzyme shape changes if the pH is not suitable (too much H+ or OH-)
Graph: Rate of reaction increases to point which is optimal environment, then decrease
Affect of substrate concentration on enzyme function
Higher substrate conc. increases reaction rate but are limited by the conc. of enzymes available
Graph: Rate of reaction increases to the saturation point, at which the rate can not increase any more.
Affect of enzyme concentration on enzyme function
Higher enzyme conc. increases the rate of reaction infinitely (assume unlimited substrates)
Graph: Rate of reaction increases forever (linear)
What improves enzyme function?
Coenzymes (organic, vitamins)
Cofactors (inorganic, trace metals: zinc, copper, etc.)
Inhibitors
Competitive inhibitors compete with substrate for space in active site
Non-competitive inhibitors attach in “allosteric site” and alter shape of enzyme (shift where stuff goes)
A substrate is more likely to overcome the competitive inhibitor if it has a greater concentration because it is more likely to be near the vacant enzyme.
If a covalent bond occurs in inhibition, the inhibition can be irreversible - like in poisons (only H-bonds or ionic bonds are used with substrates)
Benefit of inhibitors
If there is excess product, feedback inhibition will occur (product re-enters enzyme to prevent reaction form occurring and wasting recourses)
Ingestion
the act of eating
digestion (and what becomes what)
the processing and breakdown of food:
- Mechanically broken down (chewing)
- inc. surface area - Chemical digestion breaks down molecularly:
- proteins –> amino acids
- polysaccharides –> monosaccarids
- nucleic acids –> nucleotides
- fat –> glycerol + fatty acids
Abosrbtion
products of digestion are absorbed by cells lining digestive tract
NUTRIENTS are absorbed in the small intestine through epithelial cells in one of the villi
Be able to describe path of digestive system what happens in each organ and why and any accessory organs and their functions
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