Cell Membrane Structure and Function: Fluid Mosaic Model & Homeostasis

What is the primary function of the plasma membrane?

To help maintain a cell's homeostasis.

What does selective permeability mean?

It refers to the ability of a membrane to allow some substances to pass through while keeping others out.

What analogy is used to explain selective permeability?

A fish net that captures fish while allowing water and other debris to pass through.

What is the structure of the plasma membrane primarily composed of?

A phospholipid bilayer.

What are the components of a phospholipid?

A glycerol backbone, two fatty acid chains, and a phosphate-containing group.

How are the phospholipids arranged in the plasma membrane?

In a bilayer with the polar heads facing outward and the nonpolar tails facing inward.

Why are the polar heads of phospholipids attracted to water?

Because they are polar molecules.

What is the role of cholesterol in the plasma membrane?

To maintain membrane fluidity and stability.

What are transport proteins?

Proteins that facilitate the movement of substances across the plasma membrane.

What is the fluid mosaic model?

A model that describes the plasma membrane as a flexible structure with various proteins embedded in or attached to a fluid phospholipid bilayer.

What is homeostasis?

The process of maintaining balance in an organism's internal environment.

What types of cells have a plasma membrane?

Both prokaryotic cells and eukaryotic cells.

What happens to hydrophobic substances in relation to the plasma membrane?

They can cross the membrane due to the nonpolar interior of the phospholipid bilayer.

What is the significance of the phospholipid bilayer's arrangement?

It creates a barrier that is polar at its surfaces and nonpolar in the middle, allowing for selective permeability.

What is the role of carbohydrates in the plasma membrane?

To serve as recognition sites for cell signaling and communication.

How does the plasma membrane contribute to a cell's survival?

By controlling the entry and exit of substances, thus maintaining homeostasis.

What is the relationship between the plasma membrane and the cell's environment?

The plasma membrane acts as a boundary that separates the cell from its watery environment.

What is the significance of the term 'fluid' in the fluid mosaic model?

It indicates that the components of the membrane can move and shift, allowing flexibility.

What does the term 'mosaic' refer to in the fluid mosaic model?

It refers to the diverse array of proteins that float in or on the fluid lipid bilayer.

What type of substances cannot easily move through the plasma membrane?

Water-soluble substances

What components move within the plasma membrane?

Cholesterol, proteins, and carbohydrates.

What role do receptor proteins play in the plasma membrane?

They transmit signals to the inside of the cell.

How do transport proteins contribute to the plasma membrane?

They move needed substances or waste materials through the plasma membrane, contributing to selective permeability.

What is the benefit of the bilayer structure of the plasma membrane?

It allows for selective permeability and fluidity, maintaining homeostasis.

Where are cholesterol molecules located in the plasma membrane?

Among the phospholipids.

What do carbohydrates attached to proteins in the plasma membrane do?

They define the cell's characteristics and help cells identify chemical signals.

What happens to nerve cells during a stroke related to glutamate?

They release a flood of glutamate when oxygen is low, which can destroy the calcium pump.

What is disrupted when nerve cells contain excess calcium after a stroke?

Homeostasis is disrupted.

What does the fluid mosaic model describe?

The plasma membrane as a structure where substances can move around within the membrane.

How do phospholipids behave in the plasma membrane?

They can move sideways within the membrane, creating a 'sea' in which other molecules can float.

What is the significance of the pattern created on the surface of the plasma membrane?

It reflects the different substances present in the membrane, forming a mosaic.

What is selective permeability?

A property of the plasma membrane that allows it to control what enters and leaves the cell.

What are the main components that provide basic structure to the plasma membrane?

Two layers of phospholipid molecules.

What effect does increased cholesterol have on the plasma membrane?

It can affect the fluidity and stability of the membrane.

What is the role of the calcium pump in nerve cells?

It regulates the movement of calcium ions into and out of nerve cells.

What happens to the calcium pump during a glutamate flood?

It is destroyed, leading to excess calcium in the cells.