Untitled Flashcard Set

What are the main functions of the plasma membrane?

Controls substance entry and exit, maintains homeostasis, allows cell recognition, receives signals, facilitates cell attachment, and changes shape.

What does the fluid mosaic model describe?

A flexible structure of the membrane made of phospholipids, proteins, cholesterol, and carbohydrates.

What are the components of a phospholipid molecule?

A hydrophilic head, two hydrophobic fatty acid tails, a glycerol backbone, and a phosphate-containing group.

How do phospholipids organize in a bilayer?

Hydrophilic heads face the watery environments; hydrophobic tails face inward.

What is the role of integral proteins in the plasma membrane?

Integral proteins have hydrophobic regions that interact with the membrane and hydrophilic regions that interact with the aqueous environment.

What is the function of carbohydrates on the membrane surface?

Carbohydrates aid in cell recognition, attachment, and interaction with environments.

What factors affect membrane fluidity?

Fatty acid structure, temperature, and cholesterol content.

What is passive transport?

Movement of substances down their concentration gradient without directly requiring energy.

What is osmosis?

The net movement of water across a selectively permeable membrane from high to low free water concentration.

What is the sodium-potassium pump's primary function?

To move 3 Na⁺ out of the cell and 2 K⁺ into the cell, using ATP for energy.

What are the three types of active transporters?

Uniporter, symporter, and antiporter.

How does facilitated diffusion differ from simple diffusion?

Facilitated diffusion requires membrane proteins for substances that cannot easily cross the hydrophobic membrane.

What is endocytosis?

The process by which the plasma membrane folds inward to bring material into the cell.

What occurs during exocytosis?

A vesicle containing material fuses with the plasma membrane to release contents outside the cell.

Define osmolarity.

The total concentration of dissolved solute particles in a solution.

What is the difference between primary and secondary active transport?

Primary transport uses ATP directly; secondary transport depends on gradients established by primary transport.

What happens to a cell in a hypertonic solution?

Water leaves the cell, causing it to shrink.

What is receptor-mediated endocytosis?

The process where receptors on the cell surface bind specific substances, facilitating their uptake through vesicle formation.