Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Enzymes what are they - Laurel County Schools
Document related concepts
Transcript
What are they? Enzymes Why do we need them? Name some examples ? Enzymes Globular proteins that catalyse chemical reactions in living organisms Enzymes Globular proteins that catalyse chemical reactions in living organisms Properties Specific Increase rate of the reaction Unchanged at the end of the reaction Enzymes Need them because... Reactions too slow to maintain life Can’t increase temperatures/pressure in cells (fatal) Enzymes Are Proteins The enzyme binds to the substrates by its active site The active site is a pocket formed by the folding of the protein where the substrates bind. Enzymes Are Proteins The enzyme binds to the substrates by its active site The active site is a pocket formed by the folding of the protein where the substrates bind. Active site The active site involves a small number of key residues that actually bind thesubstrates The rest of the protein structure is needed to maintain these residues in position Lock and Key Enzyme reactions enzyme + substrate enzyme-substrate complex Enzyme reactions enzyme + substrate E +S enzyme-substrate complex ES Enzyme reactions enzyme + substrate enzyme-substrate complex E +S ES enzyme-substrate complex ES enzyme + product E +P How do enzymes work? An Example An Example Sucrose + H2O Glucose + Fructose An Example Substrates Sucrose + H2O Glucose + Fructose Products For a reaction to occur the sucrose and water would have to collide with enough energy to break and form bonds This is the activation energy Sucrose + H2O + Substrates Glucose + Fructose + Products Energy Progress of reaction Energy Substrates Progress of reaction Energy Substrates Progress of reaction Products High energy intermediate Energy Substrates Progress of reaction Products High energy intermediate Activation energy Energy Substrates Progress of reaction Products The minimum amount of energy needed to start the reaction, leading to the formation of a high energy intermediate = The Activation energy High energy intermediate Activation energy Enzymes reduce the height of the energy barrier Energy Substrates Progress of reaction Products Enzyme activity How fast an enzyme is working Rate of Reaction Rate of Reaction = Amount of substrate changed (or amount product formed) in a given period of time. Enzyme activity Temperature pH Four Variables Enzyme Concentration Substrate Concentration Temperature 5- 40oC Increase in Activity Rate of Reaction 40oC - denatures 0 <5oC - inactive 10 20 30 40 50 60 Effect of heat on enzyme activty If you heat the protein above its optimal temperature bonds break meaning the protein loses it secondary and tertiary structure Effect of heat on enzyme activty Denaturing the protein ACTIVE SITE CHANGES SHAPE SO SUBSTRATE NO LONGER FITS Even if temperature lowered – enzyme can’t regain its correct shape pH Rate of Reaction Narrow pH optima Disrupt Ionic bonds - Structure Effect charged residues at active site 1 2 3 4 5 6 7 8 9 Rate of Reaction Enzyme Concentration Enzyme Concentration Substrate Concentration Rate of Reaction Active sites full- maximum turnover Substrate Concentration What is digestion? Breaking down large, insoluble molecules into smaller, soluble molecules that can be absorbed through the wall of the small intestine What breaks down the large molecules? Digestive enzymes made by specialised cells inside glands Some enzymes are... Amylase Carbohydrates Protease Lipase Proteins Lipids The enzymes break down... Carbohydrates Proteins Lipids (fats) Digestion animation Simple sugars Amino acids Fatty acids + glycerol What does bile do? • Bile is produced in the liver and stored in the gall bladder. • The enzymes in the small intestine need an alkaline pH to work best, so bile passes into the small intestine and neutralizes acid from the stomach. • Bile also emulsifies fat droplets to increase their surface area Why do you think there is acid in the stomach? • Kills bacteria in food – protects us • Denatures proteins – makes digestion easier • Activates stomach enzymes – these only work in acidic conditions • Ever wondered why PEPSIN (stomach enzyme) doesn’t digest our own stomach? • Pepsin is inactive when first made and is only activated by HCL to start digesting proteins. This powerpoint was kindly donated to www.worldofteaching.com http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.
