Plasma membrane and the fluid mosaic model

Front

What is the plasma membrane?

Back

The plasma membrane is a biological membrane that separates and protects the interior of all cells from the external environment.

Front

What is the fluid mosaic model?

Back

The fluid mosaic model describes the structure of the plasma membrane as a mosaic of various components (lipids, proteins, carbohydrates) that move fluidly within the layer.

Front

What is passive transport?

Back

Passive transport is the movement of substances across a cell membrane without the use of energy, typically along the concentration gradient.

Front

What is active transport?

Back

Active transport is the movement of substances across a cell membrane against the concentration gradient, requiring energy (ATP).

Front

What role do phospholipids play in the plasma membrane?

Back

Phospholipids form the bilayer of the plasma membrane, with hydrophilic heads facing outward and hydrophobic tails facing inward, creating a barrier to most water-soluble substances.

Front

Why can't sodium ions easily cross the plasma membrane?

Back

Sodium ions are charged and hydrophilic, making it difficult for them to diffuse through the hydrophobic lipid bilayer of the plasma membrane.

Front

What is osmosis?

Back

Osmosis is the diffusion of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Front

What happens to a cell in a hypertonic solution?

Back

In a hypertonic solution, water moves out of the cell, causing it to shrink.

Front

What is the function of cholesterol in the plasma membrane?

Back

Cholesterol helps to stabilize the plasma membrane's fluidity at body temperature, preventing it from becoming too rigid or too fluid.

Front

What are integral proteins?

Back

Integral proteins are proteins that are embedded within the lipid bilayer of the plasma membrane and can span across the membrane.