Some food molecules (eg; proteins) → too large + insoluble → cannot diffuse through cell membrane
Enzymes: required to break these large molecules into smaller, simpler, soluble and diffusible molecules
There are Digestive Enzymes
- Amylase - Starch into Maltose
- Maltase → maltose into glucose
- Protease → proteins to polypeptides, then to amino acids
- Lipase → fats to fatty acids and glycerol
Enzymes Either Build Up / Break Down Complex Substances
- reactions that build up complex substances (anabolic reactions)
- reactions that break down complex substances (catabolic reactions)
Reactions that Build up Complex Substances
- cells build up/ synthesize complex substances into simpler ones
Eg:
- amino acids taken into cells may be used to build up proteins
- Cytoplasm contains special enzyme to catalyze such reactions
- In photosynthesis → glucose is synthesize from and water. Chemical reactions involved in photosynthesis → catalyzed by enzymes
Reactions that Break down Complex Substances
-c ells break down complex substances to simpler substances
Eg:
-
large, insoluble, complex food molecules broken down to small, simple, soluble, diffusible molecules by digestive enzymes
-
in cell respiration → glucose is broken down to release energy and form and water.
- process involves series of chemical reaction → each catalyzed by a diff. enzyme
- enzymes act together to completely break down glucose
-
Hydrogen peroxide - sometimes produced during chemical reaction in cells.
- Substance is toxic to cells.
- Both plant and animal cells produce the enzyme catalase - to catalyze to break down hydrogen peroxide to water and oxygen.
- Removes the toxic effect
- Catalase - especially abundant in the blood and liver of mammals.
Enzymes catalyze practically all the chemical reactions that occur in an organism Only produced when they are needed.