Week 5 — Energy, Enzymes & Metabolism

Why this matters

A nursing student watching a fever climb and a home cook watching an egg turn solid in the pan both see this week's ideas at work.

In plain language

Every living thing runs on energy, and this week you learn where a cell's energy comes from and how it gets spent. You will meet energy (the capacity to do work) in its two forms, moving and stored, and two rules about it that no cell can break. You will meet ATP (the small molecule a cell spends to pay for its work), the cell's everyday cash. You will meet enzymes (proteins that speed up the cell's chemistry without being used up), and you will find out why heat, acid, and too little fuel change how fast they work. Finally, you will read a potato-and-peroxide experiment from start to finish and see why a boiled enzyme stops working for good.

• Already covered: Week 1 taught you to read a controlled experiment; Week 2 covered water and the pH scale; Week 3 covered proteins, their four levels of shape, and denaturation; Week 4 toured the cell and met the pump that spends ATP.
• This week: energy and its two laws, metabolism, ATP, enzymes, and what changes an enzyme's rate.
• How they connect: an enzyme is one of Week 3's proteins, so its shape is its job; pH from Week 2 tells you where each enzyme works; and the lab is read with Week 1's experiment habits.
• Where we're going next: Week 6, Cellular Respiration, follows a glucose molecule through the pathways that recharge ATP, and every step of those pathways is run by an enzyme.

Focus

How does a cell pay for its work, and what sets the speed of its enzymes?

By the end of this module, you should be able to:

• [ ] sort energy as kinetic or potential and state the two laws in plain words
• [ ] sort reactions as catabolic or anabolic and trace the ATP and ADP cycle
• [ ] explain how an enzyme lowers activation energy and is reused
• [ ] tell a slowed enzyme from a denatured one and compute the catalase averages

To-do

Plan your week

1. Read Chapter 5 (about 40 minutes), then the lecture.
2. Work the lecture tutorial (60–90 minutes) and the practice set (about 20 minutes).
3. Run the Biology Lab & Inquiry (about 2 hours), then the discussion and the assignment.
4. Take the quiz.

This week's checkpoint: say why a cold potato still foams but a boiled one does not.

Take it in order, and ask your instructor if a step snags.

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