Enzymes

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  • Created by: Aleena
  • Created on: 13-04-19 12:25
Catalyst
a substance that increases the rate of a chemical reaction but doesn't become altered/changed during the reaction, so can be reused again
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Enzyme
a globular protein that is a biological catalyst made by cells that increases rate of reaction, without being changed.used up itself
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Intracellular Enzyme
Enzymes that catalyse reactions within cells
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Examples of Intracellular Enzymes?
Catalase (catabolic enzyme)-helps the breakdown of Hydrogen peroxide into water & oxygen.
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Where are intracellular enzymes found inside cells?
free in solution e.g in cytosol,nucleoplasm,mitochondrial matrix,stroma of chloroplasts. OR fixed in place on the plasma membrane e.g.digestive enzymes like Sucrase attactched to cell membrane of cells lining the gut
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Extracellular Enzymes?
Enzymes that catalyse reactions outside cells
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Examples of Extracellular Enzymes?
digestive enzymes that breakdown food in the gut lumen e.g Amylase breaks down starch into Maltose or Trypsin which breaks down protein into peptides/amino acids
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Which organism relies entirely on extracellular digestion?
Fungal Hyphae-secrete enzymes onto the food directly, where it is digested into simple molecules & then is absorbed thru hyphal walls
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Specificity?
the relationship between an enzyme & the only type of molecule that fits into its active site.
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What determines the specificity of an enzyme?
the shape of its active site, which is complementary to the shape of the substrate molecule
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Active site?
area of enzyme has shape complementary to specific substrate . Its made of small number of amino acids within polypeptide chain.R groups on these amino acids determine type of substrate fits e.g.hydrophobic R group attract nonpolar substrates
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Enzyme-Substrate Complex
the structure that forms when a substrate fits into an active site
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Lock and key hypothesis
the idea of the substrate fits exactly into active site.Interactions between R groups within active site & substrate stabilise the enzyme-substrate complex.substrate is altered & forms product-enzyme product complex
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enzyme-product complex
the structure that forms in the active site after the reaction is complete but before the product(s) leaves
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Induced-fit Hypothesis
The theory that the active site of an enzyme changes shape during binding of a substrate molecule-this puts strain on substrate-leads to reaction
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Activation energy
the energy that is needed to overcome the energy barrier to allow a recation to occur.Enzymes provide an alternative pathway with a lower activation energy for the reaction
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Enzyme

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a globular protein that is a biological catalyst made by cells that increases rate of reaction, without being changed.used up itself

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Intracellular Enzyme

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Card 4

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Examples of Intracellular Enzymes?

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Card 5

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Where are intracellular enzymes found inside cells?

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