2.4 Chemical Reactions

Sponge: Set up Cornell Notes on pg. 17

2.5 Enzymes

Essential Question:

How does a catalyst affect the activation energy of a chemical reaction?

2.5 Enzymes

How does a catalyst affect the activation energy of a chemical reaction?

• Ch. 2 Quiz on Monday 9/8

• Notebook Check on Wed 9/10

KEY CONCEPTEnzymes are catalysts for chemical reactions in living things.

2.5 Enzymes

KEY CONCEPTEnzymes are catalysts for chemical reactions in living things.

2.5 Enzymes

Who would win this race? Why?

Finish Line

Team #1

Team #2

2.5 Enzymes

• Catalysts are substances that speed up chemical reactions.– decreases or lower activation energy– Therefore, increasing the reaction rate

2.5 Enzymes

Pg. 16 –Split in 1/3s Enzymes (2 videos)Catalysts (1 video)

• 5 bullets

• 7 bullets

Catalyst drawing

Hemotoxins Neurotoxins

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Catalyst Video

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Enzymes: A Fun Introduction Video 4m45s

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• Enzymes are catalysts in living things.– Enzymes are needed for almost all processes.

- Breaking down food and building proteins

– Most enzymes are proteins.

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Enzymes and Digestion Video

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Activation energy

Without a catalyst

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Activation energy

With a catalyst the reaction starts faster!!!!!!

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Activation energy without a catalyst

Activation energy with a catalyst

Draw this picture on the middle 1/3 of pg. 16 to show how catalysts speed up chemical reactions

2.5 Enzymes

How does a catalyst affect the activation energy of a chemical reaction?

2.5 Enzymes

Answer

Decreases the activation energy needed to start a chemical reaction AND also increases the rate of the chemical reaction.

2.5 Enzymes

• An enzyme’s function depends on its structure (shape)

– An enzyme’s structure allows only certain reactants to bind to the enzyme.

– Substrates- the specific reactants that enzymes act on– Bind at active sites substrates

(reactants)

enzyme

Substrates bind to anenzyme at certain places called active sites.

• Ex: Amylase- ONLY breaks down starch• Starch is the substrate for

amylase

• Ex: Lactase ONLY breaks down lactose• Lactose is the substrate for

Lactase

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Like a puzzle piece!!!!!

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Ex. Of Temperature’s Effect on Enzymes

– Enzymes work best in a small temperature range around the organism’s body temperature (98.6°)

– Changes in temperature affect the shape and function of an enzyme

Why is having a high fever a problem?

2.5 Enzymes

• The lock-and-key model helps illustrate how enzymes function.– If an enzymes structure (shape) changes, it may not work

at all (think: puzzle pieces)

Substrates bind to anenzyme at certain places called active sites.

The enzyme bringssubstrates together and weakens their bonds.

The catalyzed reaction formsa product that is releasedfrom the enzyme.

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Enzyme Video

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Classwork/Homework

• Read about Enzymes• Answer questions 1-4 on the bottom of the reading

• Ch. 2 Quiz on Monday 9/8

• Notebook Check on Wed 9/10

2.5 Enzymes

1. The maltase enzyme is perfectly shaped to accept a maltose molecule

2. The maltose binds to the enzyme at the activation point

3. 2 glucose molecules are released

1. The lactase enzyme accepts a lactose molecule

2. The lactose binds to the enzyme at the activation point

3. Glucose molecules are released

4. If a person is lactose intolerant, the body cannot digest food or drinks with lactose

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Enzymes in Snake Venom

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How might putting ice on a snake bite slow down the destructive enzymes in the snake venom?

– Changes in temperature affect the shape and function of an enzyme!!!!!

– By putting ice on a snake bite, until help arrives, you may slow down the enzymes in the snake venom from doing too much damage to your cells

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Hemotoxins (bottom of pg. 16)• Hemotoxins are toxins that destroy red blood cells, disrupt blood clotting,

and/or cause organ degeneration and generalized tissue damage.

• Injury from a hemotoxic agent is often very painful and can cause permanent damage and in severe cases death. Loss of an affected limb is possible even with prompt treatment.

• The process by which a hemotoxin causes death is much slower than that of a neurotoxin

• Snakes which envenomate a prey animal may have to track the prey as it flees. Typically, a mammalian prey will stop fleeing not because of death, but due to shock caused by the venomous bite.

• Dependent upon species, size, location of bite and the amount of venom injected, symptoms in humans such as nausea, disorientation, and headache may be delayed for several hours.

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Neurotoxins (bottom of pg. 16)

• Neurotoxins can adversely affect function in both developing and mature nervous tissue

• Neurotoxin activity can be characterized by the ability to inhibit neuron control over ion concentrations across the cell membrane, or communication between neurons across a synapse

• Macroscopic manifestations of neurotoxin exposure can include widespread central nervous system damage such as intellectual disability, persistent memory impairments, epilepsy, and dementia

• Additionally, neurotoxin-mediated peripheral nervous system damage such as neuropathy (signals don’t make it through) or myopathy (muscle fibers do not work) is common.

2.5 Enzymes

Snake Venom Enzymes and their Reactions Reading

1. Explain how the enzymes in snake venoms can lead to death.

2. What would happen to a person bit by a snake whose venom contains the enzyme “cholinesterase”?

3. Create your own snake venom.

– Choose 6 of the enzymes listed.

– In your own words, describe each enzyme’s effect on prey

ON Enzyme Handout

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4. Predict what would happen to a person bitten by a snake whose venom contained hemotoxic properties.

5. Africa’s Black Mamba has neurotoxic venom. Explain what would happen to you if you were bitten by a Black Mamba.

ON Enzyme Handout Snake Venom Videos

Snake Venom: Black Mamba Video (15 mins)

Snake Venom and Human Blood Video (2mins)