INVESTIGATING ENZYMES SE Bio.9C – Investigate and identify role of enzymes

Vocabulary Enzyme – a special protein that helps to speed up chemical reactions necessary for life. Catalyst – substance that speeds up the rate of chemical reaction. Substrates – chemicals that are transformed with the help of enzymes (reactants) Activation Energy- the energy needed to start a chemical reaction

Vocabulary Continued Substrate Complex - a non-covalent complex composed of a substrate bound to the active site of the enzyme Active Site - the part of an enzyme where substrates bind and undergo a chemical reaction. Product – a substance produced in a chemical reaction.

Enzyme Design Breaking down molecules 1. 4. 3. 2. Active Site Enzyme Sucrose H20 Glucose Fructose 1. The substrate sucrose consists of glucose and fructose bonded together

Enzyme Design Breaking down molecules 1. 4. 3. 2. Active Site Enzyme Sucrose H20 Glucose Fructose 2. The substrate binds to the enzyme forming an enzyme substrate complex.

Enzyme Design Breaking down molecules 1. 4. 3. 2. Active Site Enzyme Sucrose H20 Glucose Fructose 3. The binding of the substrate and enzyme places stress on the glucose-fructose bond and the bond breaks.

Enzyme Design Breaking down molecules 1. 4. 3. 2. Active Site Enzyme Sucrose H20 Glucose Fructose 4. Products are released and the enzyme is free to bind other substrates.

Characteristics Enzymes can be re-used and remain unchanged. Found in all living things Chemical reactions such as respiration, digestion, and photosynthesis would be too slow to sustain life without the help of enzymes !

Characteristics Enzymes lower the amount of activation energy needed!!

Characteristics Activation Energy 10

Characteristics Enzymes must be shaped exactly to suit their own substrate (Lock and Key)

Most enzymes end in “ase” Characteristics Most enzymes end in “ase” SUBSTRATE ENZYME Urea Urease Lipid Lipase Lactose Lactase Lactase only works with Lactose etc.

Catabolic/decomposition chemical reactions Involve the BREAKDOWN of big molecules into smaller ones (Hydrolysis)

Catabolic/decomposition chemical reactions An example of a BREAKDOWN reaction. AMYLASE breaks down STARCH into MALTOSE.

Anabolic/synthesis chemical reactions BUILD UP smaller molecules into bigger ones (Dehydration Synthesis)

Anabolic/synthesis chemical reactions An example of a SYNTHESIS reaction... PHOSPHORYLASE builds up glucose(-1 phosphate) into STARCH.

One More Time ……

DENATURATION Enzymes are made of proteins Proteins are sensitive to external conditions such a temperature, pH, salt levels etc If conditions change it can cause the active site of an enzyme to change shape When this happens, the substrate can no longer fit and the enzyme quits working This is called DENATURATION

Temperature & Enzyme Activity The rate of enzyme activity increases with temperature up to a maximum (OPTIMUM TEMP.) then falls to zero as the enzyme is denatured. 19

pH & Enzyme Activity pH also affects the rate of enzyme activity. Each enzyme has its own range of pH in which it will work. Examples : The enzyme PEPSIN only works between pH 1-4 (acidic) The enzyme CATALASE only works between pH 8-11 (alkaline) TRYPSIN works between pH 6-9. 20

Enzymes vary in the pH and temperatures that make them work best! This enzymes becomes denatured beyond 40OC Could be protease (found in the stomach) Could be protease (found in the stomach) Could be amylase (found in the intestine) Could be amylase (found in the intestine) Enzyme activity Temp pH Enzyme activity Temp pH 400C

Apple Experiment Observe the two apple bites. What is different about them? Why? An enzyme present in apples is called catecholase. When catechol and oxygen interact, the enzymatic reaction causes the apple to brown. The low pH of the lemon, however, stops this reaction.

Use the drawing to answer the question

Use the drawing to answer the question

Where can we find them? Enzymes are used in washing powders to help digest food stains. Biological washing powders will only work on 400C or lower. Best to have examples of meat tenderiser and small packet of washing powder to show pupils! Washing powders

Enzymes are used in baby foods to “pre-digest” the proteins. Where can we find them? Enzymes are used in baby foods to “pre-digest” the proteins. Enzymes are used to convert starch into sugar which can then be used by the body for nutrition. Meat tenderizers

Where can we find them? Poultry Production: http://www.youtube.com/watch?v=JNTUQALbWWo Digestion: http://www.youtube.com/watch?v=KED6BHVM97s

The concept of metabolism Metabolism - all the chemical reactions taking place inside living organisms. (require enzymes) Examples: photosynthesis respiration movement growth reproduction