Unit 2A Pt 2 - Chemical Reactions

Chemical Reactions
Dehydration, Hydrolysis & Conservation of Matter

Standards

HS-LS1-6:

Construct and revise an explanation based on evidence for how carbon, hydrogen, and oxygen from sugar molecules may combine with other elements to form amino acids and/or other large carbon-based molecules. 

Lesson Objectives

• Use evidence to explain that all organisms take in matter and rearrange atoms in chemical reactions.

• Use evidence to explain that chemical reactions can create products that are more complex than the reactants, and that chemical reactions involve changes in the energies of the molecules included in the reactions. 

• Explain how atoms from sugar molecules combine with other elements to form large carbon-based molecules while conserving matter.

• You are often told to eat healthy food.

• Our bodies are growing new cells and repairing tissues for our entire lives.

• All organisms need food matter to build and repair their bodies.

• Plants make their own food (glucose) using photosynthesis.

• Animals cannot make their own glucose, so they must get it by eating other organisms.

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​You are what you eat...

• A cow eats grass.

• The cow’s digestive system performs many chemical reactions that break down the plants into smaller molecules.

• The cow uses these molecules to create new biomolecules that grow new cells, repair body tissue, and perform other cell functions. 

• These biomolecules include DNA, proteins, lipids, and carbohydrates.

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​The Big Picture

• Water (H₂O) is the molecule that is used to break macromolecules down.

• These smaller molecules are rearranged into new molecules that your body uses to create different molecules!​

Drink Water with your meal!

When water (hydro-) is removed (de-), the molecule is synthesized (created) and when water is added the molecule is sliced (rhymes with -lyse: to cut or break).

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​Dehydration Synthesis & Hydrolysis

Multiple Choice

What process is shown in this picture?

• Dehydration synthesis

• Hydrolysis

Multiple Choice

What process is shown in this picture?

• Dehydration Synthesis

• Hydrolysis

• Enzymes help break down your food into macromolecules.

• This allows the body to use the smaller molecules to form new biomolecules.

Build new molecules

​Enzymes are responsible for metabolism, the sum of all chemical reactions in the body.

​​Metabolism

• Enzymes are proteins that
  work as a catalyst to speed up, or catalyze, chemical reactions.

• Enzymes lower the activation energy needed for the reaction to occur.

• The shape of each enzyme fits the shape of a specific reactant molecule, or substrate.

• The substrate bonds to the enzyme at the active site.

• The enzyme weakens the bonds of the substrate & releases a new product.

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Enzymes & Substrates

​The shape of each enzyme fits the shape of a specific reactant molecule, or substrate.

• The substrate bonds to the enzyme at the active site.

• The enzyme weakens the bonds of the substrate.

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Enzymes & Substrates

• Another way enzymes lower activation energy is by holding two substrates in neighboring sites, enabling them to react more easily.

• Enzymes can also help form new bonds between molecules to produce a more complex molecule.

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​Enzymes Continued

You eat a hamburger and your body breaks down the protein (biomolecules).
The enzyme, protease, breaks down the beef into the amino acid building blocks.
Your body uses these amino acids to create human proteins.

​Big Picture

Multiple Choice

Which reaction shows the amount of energy required WITH (A or B) enzymes?

• BLACK line, Reaction A

• RED line, Reaction B

Multiple Choice

Enzymes ___ reactions by ___ activation energy.

• slow down, lowering

• slow down, increasing

• speed up, lowering

• speed up, increasing

Involves the breaking of many bonds within a protein molecule, causing a looser, structure that cannot function as it normally did.

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Denaturation

Multiple Choice

What is the process called when a protein or enzyme is heated above its optimal temperature and no longer maintains the original structure or function called?

• catalyzed

• denatured

• hydrolyzed

• dehydrated

Multiple Choice

What is the optimal temperature of this enzyme?

• 50 C

• 40 C

• 60 C

• 70 C

​Law of Conservation of Mass

​Antoine Lavoisier - "Revolutionized Chemistry"

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• ​Lavoisier discovered that "Mass can not be created or destroyed" by carefully measuring the product and reactants in many of the chemical reactions he was researching.

• ​Law of Conservation of Mass states that: "Mass can not be created or destroyed"

​Elements and Compounds

• ​An element is a single type of atom

• A compound is one or more different atoms chemically combined

• A molecule is a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.

​Products and Reactants in a Chemical Reaction

​Reaction between Methane and Oxygen :

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​All of the atoms that were present at the beginning of the reaction (reactants) are still present in the products. They have just been moved around or transformed!

Same starting and ending mass!

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Products vs. Reactants

​RAP = Reactants Arrow Products

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​Products and Reactants in a Chemical Equation

Multiple Choice

What happens to atoms in a chemical reaction?

• Atoms are destroyed.

• Atoms are created.

• Atoms are rearranged.

Multiple Choice

Matter can not be created or destroyed: it can only be

• destroyed a little bit.

• invisible.

• transformed, or changed.

• None of the above.

Multiple Choice

Which section represents the reactants?

• A

• B

• C

Multiple Choice

Which of the models of a chemical reaction best represents the Law of Conservation of Mass?

• A

• B

• C

• D

Molecules in your food & water are broken down & rearranged into new molecules that are incorporated into your body tissues!

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You REALLY are what you eat!