INVESTIGATING ENZYMES

SE Bio.9C – Investigate SE Bio.9C – Investigate and identify role of and identify role of enzymesenzymes

Engage

Take a bite of an apple. On the opposite side of the apple take a second bite. Rub lemon juice on the second bite mark and set your apple aside.

How An Enzyme Works

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. The substrate sucrose consists of glucose and fructose bonded together

1.

4.

3.

2.

Active Site

Enzyme

SucroseH20

Glucose Fructose

Enzyme Design Breaking down molecules

2. The substrate binds to the enzyme forming an enzyme substrate complex.

1.

4.

3.

2.

Active Site

Enzyme

SucroseH20

Glucose Fructose

Enzyme Design Breaking down molecules

3. The binding of the substrate and enzyme places stress on the glucose-fructose bond and the bond breaks.

1.

4.

3.

2.

Active Site

Enzyme

SucroseH20

Glucose Fructose

Enzyme Design Breaking down molecules

4. Products are released and the enzyme is free to bind other substrates.

1.

4.

3.

2.

Active Site

Enzyme

SucroseH20

Glucose Fructose

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 !

Enzymes lower the amount of activation energy needed!!

Characteristics

Activation Energy

Characteristics

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

Characteristics

Most enzymes end in “ase”

SUBSTRATE ENZYME

Urea Urease

Lipid Lipase

Lactose Lactase

Lactase only works with Lactose etc.

Characteristics

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)

An example of a SYNTHESIS reaction...

PHOSPHORYLASE builds up glucose(-1 phosphate) into STARCH.

Anabolic/synthesis chemical reactions

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 ActivityTemperature & Enzyme ActivityThe rate of enzyme activity increases with temperature up to a maximum (OPTIMUM OPTIMUM TEMPTEMP.) then falls to zero as the enzyme is denatured.

pH & Enzyme ActivitypH & Enzyme Activity

pHpH also affects the rate of enzyme activity. Each enzyme has its own range of pHrange of pH in which it will work.

Examples : The enzyme PEPSINPEPSIN

only works between pH 1-4 (acidic)

The enzyme CATALASECATALASE only works between pH 8-11 (alkaline) TRYPSIN works between pH 6-9.

This enzymes becomes

denatured beyond 40OCEnzyme

activity

Temp pH pH400C

Could be protease (found in the stomach)

Could be amylase (found in the intestine)

Enzymes vary in the pH and temperatures that make them work best!

Enzyme activity

Temp pH pH

Could be protease (found in the stomach)

Could be amylase (found in the intestine)

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?

Washing powders

Enzymes are used in washing powders to help digest food stains. Biological washing powders will only work on 400C or lower.

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

Where can we find them?

The concept of metabolism Metabolism - all the chemical reactions

taking place inside living organisms.

(require enzymes)

Examples:– photosynthesis– respiration– movement– growth– reproduction