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Enzymes - Coggle Diagram
Enzymes
Enzyme Action
Digestion, anabolic (creating reactions) and catabolic (breaking down reactions) reactions are catalysed by enzymes.
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Molecules in a solution move and collide randomly, temperatures and pressures increase the molecules move faster as they have more kinetic energy. So higher number of collisions and rate of reaction.
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Lock and Key hypothesis
The active site of the enzyme is complementary to the substrate and it's shape is determined by the enzymes tertiary structure as enzymes are made of proteins.
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Enzyme-Substrate complex is formed when substrate binds onto active site. Substrate then reacts and products are formed in an enzyme-product complex and are released.
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Induced-fit Hyopthesis
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Active sites tertiary structure strengthens binding between enzyme + substrate, which is initially weak This puts strain on substrates tertiary structure and can weaken bonds. So it lowers activation energy
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Extracellular Enzymes are enzymes that work outside cells. Single-celled organism release onto immediate environment to break down larger molecules to then absorb. Multicellular organisms break down large molecules in digestive system e.g. amylase, trypsin, to absorb into bloodstream. Both organisms use to make use of polymers for nutrition.
Digestion of Protein happens in the small intestine.
Protein --> peptides by trypsin (a type of protease, produced in pancreas).
Peptides --> amino acids by other proteases + are absorbed into bloodstream.
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Digestion of Starch begins in mouth, goes to small intestine. Digested in 2 different ways.
- Starch polymers --> maltose (disaccharide).
Broken down by Amylase which is produced
in the salivary glands (into mouth as saliva) +
pancreas (into small intestine in pancreatic
juice)
- Maltose --> glucose (monosaccharide) by
maltose (in small intestine)
glucose is small enough to absorb into bloodstream
Inhibitors
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Competitive inhibitors ↓ rate of reaction but not Vmax of enzyme. Examples: Statins (inhibits enzymes in production of cholesterol), Asprin (Inhibits COX enzymes used in production of chem. responsible for pain)
- different molecule which is also complementary to active site + has a similar structure to substrate fits into active site and blocks substrate from fitting there.
- enzyme is inhibited as it cannot bind with substrate
- compete with substrates, most bind temp so effects are reversible but some exceptions (asprin)
Non-competitive inhibitors ↓ rate of reaction, ↑ enzyme / substrate conc. will not overcome effects.
- bind to an allosteric site (site other than active site)
- binding causes change in tertiary structure so change in active site shape so no longer complementary to substrate
can be irreversible, e.g. Organophosphates (insecticides/herbicides), Proton Pump Inhibitors (PPI) (block enzyme used to secrete hydrogen ions into stomach)
End-product inhibition occurs when product inhibits enzyme that made it. serves as negative-feedback so excess products aren't created + no resources are wasted. Is non-competitive + reversible.
- ATP regulates its own production through this. When ATP levels ↑, more ATP acts as inhibitor. When ATP levels ↓, less ATP acts as inhibitors so more ATP can be produced.
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Cofactors, coenzymes, prosthetic groups
Cofactor ~ A non-protein "helper" component used by enzymes to carry out function.
Coenzyme ~ An organic cofactor
Prosthetic group ~ Cofactors required by certain enzymes, tightly bound + permenant.
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Precursor activation
- Many enzymes are produced as inactive precursor enzymes (mostly damage causing within cells / actions need to be controlled)
- Often need to change tertiary structure for active site to be active. Achieved by adding cofactor
- Before cofactor added, called an apoenzyme
- Cofactor is added, then called a holoenzyme