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Catalyst or Enzymes

Aim: What are organic catalysts in the body?

Objectives:

-Explain organic catalyst as an enzyme.

-Explain organic catalyst as a protein and/or organic molecule.

-Explain “active site” and substrate.

-Explain “lock and key” model.

-Explain factors that can influence enzyme substrate complex rate of reaction.

-Explain coenzyme.

Key idea or development of lesson:

Do now: Read with comprehension and copy into notebook. Thousands of chemical reactions occur in living cells. Each of these reactions requires and is controlled by a specific (specially for that thing) substance called an enzyme. Although enzymes are needed to cause reactions to occur in the cell, the enzymes are not changed by the reaction. Enzymes can be used over and over for the same type of reaction. Substances that affect the rate or speed of a chemical reaction and are not changed by the reaction are called catalysts. Enzymes are organic catalysts and are made of protein. The enzymes used in the body need a

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coenzyme to function correctly. Coenzymes are vitamins. Every specific type of chemical reaction requires a specific type of enzyme. Without the specific enzyme the chemical reaction cannot proceed.

-An enzyme is a protein that allows a chemical reaction to proceed at a faster rate, and with less energy than if there wasn’t any enzyme.

-An enzyme is specific for a particular substrate.

-An enzyme has an “active site,” for a particular substrate to fit exactly in it.

-An enzyme can be reused many times for the same specific chemical reaction.

The reactants that bind to the enzyme are called substrates.The specific location where a substrate binds on an enzyme is called the active site.

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-The suffix of a word ending in “ase” is to indicate an enzyme and is often derived from the name of their substrate. For example, maltase is the enzyme that breaks down maltose.

Explain the difference between “ase and ose”.

Mid-summary or key questions:

-Explain why enzymes or organic catalysts are necessary for life in humans?

-What are enzymes or organic catalysts made of?

-Explain why an enzyme is an organic catalyst?

-Explain what is the substrate in the chemical reaction?

-Explain how a substrate reacts with the “active site” of an enzyme?

-Explain what is an “enzyme-substrate complex”?

-What is a coenzyme and used for?

-What do all words that indicate an enzyme have as a suffix?

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Further development of lesson: Allow students to use graph or design a graph for comprehension.

-An enzyme can be affected by the temperature, pH, and amount of enzyme and substrates in a reaction.

GlucoseSubstrates

ATP

Substratesbind toenzyme

Substratesare convertedinto products

Enzyme-substratecomplex

Enzyme(hexokinase)

ADP

Glucose-6-phosphate

Productsare released

Active site

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Enzymes enable cell reactions to proceed at normal temperatures.

At normal temperature enzymes speed up chemical reactions in the cell without requiring high temperatures. But enzymes work best at certain temperatures. The enzyme action depends on the random motion of molecules coming into contact, which brings the substrates into contact with the enzymes. This random motion increases as the temperature rises, which bring more substrates into contact with enzymes to form “enzyme - substrate complex”. If the temperature is low, the rate or speed at which “enzyme - substrate complex” form will be low. Thus, the effect of the enzyme will be reduced if temperature is low. At higher temperatures, the enzymes become more effective, because “complexes” are forming at a faster rate or speed. If the temperature is too high, the shape of the enzyme molecule changes. Its “active site” no longer fits the substrate molecule, and the enzyme loses its effectiveness. This effect is called denaturation.

The temperature of greatest effectiveness is called the optimum temperature for the enzyme. Warm - blooded animals maintain a body temperature close or near to the optimum temperature of their enzymes. In humans, this temperature is 37 degree Celsius or 98.6 degree Fahrenheit. Denaturation of most enzymes in the human body occurs at around 40 degree Celsius or 104 degree Fahrenheit. That is why an increase in body temperature of just a few degrees for a prolong period of fever can result in illness or death. See or use graph for comprehension.

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Each enzyme works best at a certain pH.

The effectiveness of an enzyme depends on the pH of the surrounding environment. Examples would be: (1) The pH of the human stomach is acid and the gastric enzyme protease pepsin, which helps in the digestion of proteins into peptide molecules or amino acids molecules in the stomach, is most effective at acid pH level of 4. (2) In the small intestine the pH level is basic. The pancreatic protease trypsin, which continues the digestion of proteins into peptide molecule and amino acids in the intestine, works best in a basic environment of the pH level of 8,5 . The enzyme that functions best at a certain level is called optimum pH. See or use graph for comprehension.

The rate or speed of an enzyme-controlled reaction depends on the concentration of enzyme and substrate.

If a certain amount of an enzyme is presented, the number of substrate molecules it can react with is limited. Thus increasing the amount of the substrate molecules will increase the rate or speed to a certain level until all the enzymes of that particular chemical reaction is occupied, and any

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increase in substrate will not affect the rate or speed of the reaction any higher. See or use graph for comprehension.

The same concept can be said, if there is a certain amount of substrate molecules to enzymes. Thus increasing the amount of enzymes will increase the rate or speed of the enzyme-substrate complex reaction to a certain level until all the substrates are used, and an increase of the enzyme will not affect the rate or speed of the reaction, because there is a limited amount of substrates. See graph for comprehension.

1)Explain how the differences in temperatures of low, normal , high, and higher temperatures effects the “enzyme- substrate complex” reaction’s rate or speed.

2)Why is the pH of the environment important for enzymes?

3)Explain how the differences of the concentration of enzymes and substrates effects the rate or speed of a “enzyme-substrate complex” reaction.

Summary question:

-Answer must be written

HOW CAN THE SPEED OR RATE OF “ENZYME-SUBSTRATE COMPLEXES” CHANGE?

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-Explain why enzymes or organic catalysts are necessary for life in humans?

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-What are enzymes or organic catalysts made of?

-Explain why an enzyme is an organic catalyst?

-Explain what is the substrate in the chemical reaction?

-Explain how a substrate reacts with the “active site” of an enzyme?

-Explain what is an “enzyme-substrate complex”?

-What is a coenzyme and used for?

-What do all words that indicate an enzyme have as a suffix?

HOW CAN THE SPEED OR RATE OF “ENZYME-SUBSTRATE COMPLEXES” CHANGE?

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