Plasma Membrane Structure and Function 5

Flashcards covering key concepts related to plasma membranes, including structure, function, transport mechanisms, and fluidity.

What is the fluid mosaic model of the plasma membrane?

It describes the plasma membrane as a fluid combination of phospholipids, cholesterol, proteins, and carbohydrates.

Name the major functions of the plasma membrane.

Defining the cell boundary, managing entry and exit of substances, receiving signals, and adhering to neighboring cells.

What are the three major components of the plasma membrane?

Phospholipids, proteins, and carbohydrates.

How do phospholipids arrange themselves in an aqueous solution?

They form a bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward.

What role does cholesterol play in membrane fluidity?

Cholesterol helps maintain fluidity by preventing tight packing at low temperatures and restraining movement at high temperatures.

What are the two types of passive transport?

Diffusion and facilitated diffusion.

Define osmosis.

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

What is tonicity?

Tonicity describes how an extracellular solution can affect the volume of a cell by influencing osmosis.

What are the types of endocytosis?

Phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Describe the difference between primary and secondary active transport.

Primary active transport directly uses ATP to move substances against their gradient, while secondary active transport uses the electrochemical gradient established by primary active transport.

What occurs during exocytosis?

Vesicles containing substances fuse with the plasma membrane and release their contents to the exterior of the cell.

What distinguishes integral proteins from peripheral proteins?

Integral proteins are embedded within the membrane, while peripheral proteins are located on the surface.

Define facilitated diffusion.

Facilitated diffusion is the process of moving substances down their concentration gradient through transmembrane proteins.

What is the primary function of glycoproteins and glycolipids?

They function in cell recognition and attachment.

What happens to a cell placed in a hypertonic solution?

Water leaves the cell, causing it to shrink.

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

To maintain a concentration gradient of sodium and potassium ions across the plasma membrane.

Which type of transport is described as moving large molecules into or out of cells?

Bulk transport (endocytosis and exocytosis).

What are the effects of temperature on membrane fluidity?

Low temperatures make the membrane more rigid, whereas high temperatures increase molecular motion and fluidity.

What is the significance of aquaporins in facilitated diffusion?

Aquaporins facilitate the rapid transport of water through cell membranes.

Describe the process of receptor-mediated endocytosis.

It is a targeted uptake of a substance that binds to receptors on the cell membrane's surface.

What occurs during phagocytosis?

The cell membrane surrounds and engulfs large particles.

In what manner does active transport differ from passive transport?

Active transport requires energy to move substances against their concentration gradient, whereas passive transport does not.

What happens to a red blood cell in an isotonic solution?

There is no net movement of water into or out of the cell.