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•How many of you have heard “Chew your food”? •Why is it important?•What does your body use to assist in digestion?•Do you know someone who is lactose-intolerant?•What does that mean?•What do they have to do?•What causes it?•Why can’t I use my truck key to get into my classroom, and vice versa?

Enzymes

• Biological processes such as digestion, synthesis, respiration and photosynthesis are made possible in living things by enzymes.

Enzymes speed up the rate of reactions in living things.

Without enzymes, the processes that keep us alive would not occur at a fast enough rate.

For example, digestion of our food would not occur quickly enough for our cells to receive food. Luckily, enzymes are added to our food as it moves through the digestive tract. These enzymes help make our food small enough to fit into our cells.

• Enzymes are catalysts, substances that speed up the rate of a chemical reaction without themselves being changed or used up during the reaction.

• Enzymes are capable of carrying out the same function over and over.

• Enzymes, like other molecules (hormones, antibodies, receptors on cell membranes) have specific shapes that determine how they function.

• Enzymes are chain-like protein molecules that are folded into precise shapes.

What happens if a protein loses its shape?

• Some molecules called substrates match precisely with the shape of certain enzymes, others don’t fit.

For example, the enzyme pepsin in your stomach acts on

protein you eat to digest it. Pepsin is not effective in digesting fat. This means that enzymes are specific.

• Enzymes help carry out many reactions in the body such as digestion and synthesis.

• Synthesis creates a larger product than the substrates, with the help of enzymes.

• Digestion breaks large molecules into smaller ones, with the help of enzymes.

Chunk! Study this diagram…

Try to label all the pieces…

• How can you always identify the enzyme?• If the end molecule is larger, is it the

process of synthesis or digestion?• What is the job of enzymes, in general?

Chunk continues..

• Explain the role of enzymes in digestion.

• What is another name for enzymes?

• Are enzymes used up in the reaction?

• How do enzymes work?

• What type of organic molecules are enzymes?

• Name some other molecules that function by shape.

Enzymes Are Picky

• Like you and me, enzymes only function well under the best of environmental conditions. Each enzyme has set of conditions that are best for it to work. These conditions are called optimal.

1. Temperature

• Most enzymes have an optimum temperature at which they function most effectively bc enzymes and substrates move faster at the optimum temperature, increasing the reaction rate.

• Higher temperatures however cause the rate to decrease bc the enzymes change shape or break apart

2. pH

• Most enzymes have an optimum pH of around 7 at which they function most effectively

• Enzymes that work in specific locations with other pH values tend to have the optimum pH values that correspond with their working environment

Chunk• Why are enzymes “picky”? (Use these terms: lock and

key, substrate, active site, specific)• What does “optimum” mean, in terms of enzyme action?• How does temperature affect enzyme rate? Why?• What do very high temps do to enzymes?• What is body temp in degrees Celsius?• What is pH?• What is the pH of strong acids…weak acids?• What is the pH of strong bases…weak bases?• What is neutral pH?• What is the optimum pH for most enzymes?• What does the term “enzyme specificity” mean?

Just for Fun!

What could the rabbit use to increase the reaction rate of the turtle?