Plasma Membrane and Cell Structure

These flashcards provide a review of key concepts related to the plasma membrane, including its structure, function, and various processes involving cellular transport and signaling.

What are the main functions of the plasma membrane?

Protects the cell, controls what goes in and out of the cell, and maintains osmotic balance.

What is the basic structure of a phospholipid?

A phospholipid consists of a hydrophobic tail and a hydrophilic head.

What does the term 'amphipathic' refer to in the context of membrane molecules?

An amphipathic molecule has both hydrophobic and hydrophilic domains.

Which major phospholipid faces the outer leaflet of the plasma membrane?

Phosphatidylcholine.

What role does cholesterol play in the plasma membrane?

Cholesterol helps to control the fluidity of the cell membrane.

What defines the asymmetry of the plasma membrane?

The different types of lipids composing the membrane and the orientation of membrane proteins.

How do transmembrane proteins differ from peripheral membrane proteins?

Transmembrane proteins span the membrane while peripheral membrane proteins associate with integral membrane proteins.

What is the fluid mosaic model?

A model that describes the plasma membrane as a two-dimensional structure where proteins and lipids are free to move, allowing for organization.

What is facilitated diffusion?

The process where proteins help carry molecules across the membrane along a concentration gradient.

What is the sodium/potassium pump and its function?

A transport mechanism that moves Na+ out of the cell and K+ into the cell against their concentration gradients, using active transport.

What is phagocytosis?

A type of endocytosis where large particles are engulfed by the cell.

Describe the role of calcium ions (Ca2+) in neurotransmitter release.

Calcium ions trigger the release of neurotransmitters from vesicles at the synapse.

What is the role of the glycosylated glycocalyx?

Covers the cell surface and protects the cell from microbes, pathogens, and mechanical stress.

How do tight junctions function in epithelial cells?

They prevent the movement of ions, liquids, and proteins, maintaining cell polarity and compartmentalization.

What is the role of active transport in maintaining cellular function?

Active transport moves molecules against their concentration gradients, which is essential for nutrient uptake and waste removal.

What is the difference between voltage-gated and ligand-gated ion channels?

Voltage-gated channels open in response to changes in membrane potential, while ligand-gated channels open when a specific molecule binds to a receptor.

What happens during depolarization in neurons?

A change in membrane potential that occurs when sodium channels open and Na+ rushes into the cell.

What is the function of clathrin in endocytosis?

Clathrin coats pits on the cytoplasmic side of the membrane, helping to form vesicles during receptor-mediated endocytosis.

What is the physical structure of bacterial cell walls and their function?

Bacterial cell walls maintain cell shape and prevent bursting due to osmotic pressure.