Energy and Cellular Processes: ATP, Enzymes, and Transport

Energy: Capacity for Change

Potential Energy: Stored energy.

Kinetic Energy: Energy from motion.

Conservation of Energy: Energy cannot be created or destroyed.

Heat: A usually random form of energy.

Entropy: A measure of disorder or randomness.

Chemical Energy: Energy stored in chemical bonds, such as food.

ATP Molecule

Draw a molecule of ATP: Adenosine-P-P-P

Metabolism

Metabolism: The total of all chemical reactions in an organism, requiring enzymes.

ATP and Cellular Work

ATP energy helps cells perform three types of work:

1. Chemical: Assists chemical reactions.
2. Transport: Performs transport work.
3. Mechanical: Moves muscle fibers, for example.

Enzyme Assistance

How do enzymes assist in chemical reactions?

1. Enzymes provide an active site specific to a substrate (like a key).
2. Once attached, the chemical reaction occurs.
3. The enzyme releases the product(s).
4. The enzyme remains unaffected.

Induced Fit: The interaction where an enzyme's active site changes shape to embrace the substrate and catalyze the reaction.

Osmosis and Solutions

Osmosis: The diffusion of water across a selectively permeable membrane.

Comparing Solutions

Hypotonic: Lower solute concentration.

Hypertonic: Greater solute concentration.

Isotonic: Same solute concentration.

Signal Transduction Pathway

1. Reception

The target cell detects an external signal molecule.

2. Transduction

The signal is converted into a form that triggers a cellular response.

3. Response

The specific cellular action in response to the signal.

Cellular Transport

Passive Transport

Diffusion across a membrane that does not require energy or ATP. Substances move from higher to lower concentration. Example: Oxygen moving from lungs to bloodstream.

Facilitated Diffusion

Assisted transport using transport proteins, does not require ATP. Example: Water movement through the plasma membrane.

Active Transport

Requires energy (ATP) and transport proteins. Example: Sodium-potassium pump in the nervous system.

ATP Energy Transfer

The transfer of which component of ATP provides energy for cellular work? How do the chemical characteristics of these components contribute to the potential energy of ATP?

The transfer of phosphate provides energy for cellular work.