Biology honors study cards - 2.3, 2.4, 2.5

Study

1. What are proteins?

Proteins are large molecules that do tons of important jobs in your body.

They are made of these elements:

• C = Carbon

• H = Hydrogen

• O = Oxygen

• N = Nitrogen

• S = Sulfur (sometimes)

Think of proteins as machines that do different jobs in your body.

Some examples:

• Enzymes speed up chemical reactions.

• Antibodies help fight infections.

• Some proteins transport materials.

• Other proteins help your muscles contract.

2. Amino acids: The building blocks

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Proteins are made of smaller building blocks called amino acids.

Think of amino acids like LEGO bricks. Different LEGO bricks connect to make something bigger.

Every amino acid has:

• Central carbon: The middle of the molecule.

• Hydrogen atom: Attached to the central carbon.

• Amino group: Contains nitrogen.

• Carboxyl group: Contains carbon and oxygen.

• R group: The part that makes each amino acid different.

MOST IMPORTANT

The R group determines the unique properties of an amino acid.

For example:

• Hydrophobic = avoids water.

• Hydrophilic = attracted to water.

• Charged = has an electrical charge.

Why does this matter?

The R groups interact with each other, causing the amino acid chain to fold into a specific shape.

3. Polypeptides vs. proteins

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Here's the difference:

1. Amino acids connect together.

2. They form a long chain called a polypeptide.

3. The polypeptide folds into a specific 3D shape.

4. That folded structure becomes a functional protein.

Remember: Structure = Function.

This means a protein's shape determines what job it can do.

What is denaturation?

Denaturation happens when a protein loses its normal shape.

When it loses its shape, it also loses its function.

Example: Imagine a key that gets bent. It might no longer fit into its lock.

That's basically what happens when a protein denatures.

4. Enzymes (VERY IMPORTANT)

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Enzymes are proteins that speed up chemical reactions.

They do this by lowering something called activation energy.

What is activation energy?

Activation energy is the amount of energy needed to get a chemical reaction started.

Think about pushing a heavy box up a hill. You need energy to get it moving.

An enzyme makes that hill smaller, so less energy is needed to start the reaction.

How enzymes work

There are four important terms:

Term

Meaning