Presentation on theme: "Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical."— Presentation transcript:
Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical reactions Remain unchanged by chemical reaction
Product Substrate Chemical Reactions A chemical reaction takes place when one or substances is chemically changed into one or more different substances. Chemical reactions take place in cells all the time. Enzyme Catalase Hydrogen peroxide Water + oxygen Manganese dioxide Catalyst
Catalysts A catalyst is a substance which speeds up a chemical reaction, without itself being changed by the reaction. 1.When a catalyst is present, less energy is needed to get the chemical reaction started. 2.When a catalyst is present, the speed of the chemical reaction is faster. 3. Although a catalyst helps a chemical reaction to happen, it is unchanged at the end of the reaction.
Biological Catalysts The biological catalyst present in the cytoplasm of plant and animal cells that speeds up the breakdown of hydrogen peroxide is called CATALASE. Hydrogen peroxide Oxygen + water catalase
2.2 Nature of Enzymes The biological catalyst present in the cytoplasm of plant and animal cells that speeds up the breakdown of hydrogen peroxide is called CATALASE. Catalase cannot speed up any other reaction. It is SPECIFIC to this reaction. Catalase Hydrogen peroxide Water + oxygen
One Enzyme – One Reaction There are thousands of different enzymes in your body. Why are there so many different enzymes? Each enzyme has its own unique protein structure and shape, which is designed to match or COMPLEMENT its substrate.
Lock & Key Hypothesis An enzyme only acts on one type of substance, or substrate. Therefore, the enzyme is said to be SPECIFIC to its one substrate. The shape of the active site (binding site) of the enzyme, matches the shape of the substrate. Allowing the two molecules to bind during the chemical reaction. This theory of enzyme action is called the ‘lock-and-key’ hypothesis.
Different enzymes for different jobs Enzymes involved in breakdown reactions Enzyme and substrate separate Enzyme-substrate complex Enzyme and products separate Enzymes involved in synthesis reactions Enzyme and substrates separate Enzyme-substrates complex Enzyme and product separate
2.3 Using a Control Why is it necessary to include a control experiment in an investigation? A control is an experiment that allows a comparison within an investigation in order to ensure that the conclusions drawn from the results are valid.
2.3 Using a Control Only one variable should be altered in an investigation, this is said to be the altered variable. It is important to ensure that all other potential variables are kept the same in the investigation, these are called the controlled variables. What was the altered variable in the last investigation you carried out? What were the controlled variables in the last investigation you carried out?
2.4 Synthesis reactions Glucose is used by leaves as energy source or transported to root for storage. Leaves make glucose. Roots convert glucose into G-1-P. Phosphorylase converts G-1-P into starch.
2.4 Synthesis reactions phosphorylase glucose-1-phosphate starch What is phosphorylase? Phosphorylase is an enzyme that synthesises starch. What is substrate of phosphorylase? Glucose-1-phosphate What is the product? Starch
2.4 Synthesis reactions phosphorylase glucose-1-phosphate starch Amylase catalyses the breakdown of starch to produce maltose. How is starch produced?
2.5 Effect of High Temperature Notes on DenaturationDenaturation Notes on Optimum temp Optimum conditions are the conditions at which an enzymes works best Rate of reactions may be affected by temperature and pH
2.5 Effect of High Temperature Notes on DenaturationDenaturation Notes on Optimum temp What happens to the activity of an enzyme at high temperatures?
Movie Effect of pH on enzymes When the pH changes outwith optimal conditions, the shape of the active site of the enzyme alters and the enzyme is denatured.
Effect of pH on enzyme activity Most enzymes work best at a pH close to neutral (pH7), but there are some exceptions. Pepsin, an enzyme found in the stomach, has an optimum pH of 2.
EnzymeSubstrateProduct(s)Degradation or synthesis? AmylaseStarchMaltoseDegradation CatalaseHydrogen peroxide Oxygen and water Degradation PepsinProteinAmino acidsDegradation PhosphorylaseGlucose-1- phosphate StarchSynthesis LipaseFatAmino acidsDegradation Enzyme Summary