AP Bio Insta-Review Topic 2.4*: Plasma Membranes

Front

What are the two main macromolecules that make up most of the plasma membrane?

Back

Phospholipids & Proteins

Front

How are phospholipids oriented in the plasma membrane?

Back

In a double layer, with fatty acid tails facing the interior and phosphate heads facing the exterior.

Front

Where would you find a membrane protein with a polar R group?

Back

As a peripheral protein in the phosphate head region.

Front

What lipid is commonly found in the plasma membrane that helps maintain its fluidity?

Back

Cholesterol.

Front

What types of materials can easily pass through the plasma membrane?

Back

Small, Nonpolar materials.

Front

What is the primary function of the plasma membrane?

Back

To protect the cell and regulate what enters and exits.

Front

What is the structure of a phospholipid?

Back

A phospholipid consists of a hydrophilic (water-attracting) phosphate head and two hydrophobic (water-repelling) fatty acid tails.

Front

What role do proteins play in the plasma membrane?

Back

Proteins assist in transport, act as receptors, and provide structural support.

Front

What is the fluid mosaic model?

Back

A model that describes the plasma membrane as a flexible layer made of lipid molecules with embedded proteins.

Front

How does cholesterol affect membrane fluidity?

Back

Cholesterol helps to stabilize the membrane's fluidity, making it less permeable to very small water-soluble molecules.