AP Biology - Membrane Transport and Permeability

These flashcards cover key concepts related to membrane transport, permeability, and osmosis, aiding in the understanding of how different molecules move across cell membranes.

What types of molecules can move freely through the cell membrane?

Small, nonpolar molecules like O2 and CO2 can move freely, while water can do so more slowly due to its slight charge.

Why can't some molecules move freely through the membrane?

Molecules cannot move freely due to the hydrophobic lipid interior and their size and charge.

What structure of the cell membrane influences molecule permeability?

The hydrophobic lipid bilayer of the cell membrane makes it semi-permeable.

What are channel proteins and carrier proteins?

Channel proteins form pores for specific substances to pass through, while carrier proteins bind to a molecule, change shape, and release it on the other side.

What is passive transport?

moves molecules from high to low concentration without the use of energy.

What is active transport?

moves molecules from low to high concentration and requires cellular energy, often in the form of ATP.

Define diffusion.

the movement of substances from an area of high concentration to an area of low concentration.

What is osmosis?

the specific diffusion of water across a semipermeable membrane.

What is facilitated diffusion?

the passive movement of molecules across a membrane that requires transport proteins.

What is dynamic equilibrium in the context of diffusion?

reached when solute concentrations are balanced across the membrane and net movement stops.

Identify the types of solutions in osmosis labs with potatoes. What happens to potatoes in each?

In a hypotonic solution, potatoes gain mass; in a hypertonic solution, they lose mass and become flaccid; in an isotonic solution, there is no net movement.

What is an isotonic solution?

is one where there is no net movement of water because the cell is at dynamic equilibrium.

What is a hypertonic solution?

has a higher concentration of solutes outside the cell, causing water to move out and shrink the cell.

What is a hypotonic solution?

has a lower concentration of solutes outside the cell, causing water to move into the cell.

What is the effect of solute concentration on water movement?

Water moves from an area of lower solute concentration to an area of higher solute concentration through a semi-permeable membrane.

What is the makeup of the outermost part of an animal cell, plant cell, and fungal cell?

all three have a plasma membrane, plant and fungal cells are surrounded by a rigid cell wall, which is absent in animal cells