Biology Chapter: Plasma Membrane Composition

Questions and Answers

What is the plasma membrane composed of?

A phospholipid bilayer in which proteins are embedded or associated with the cytoplasmic side.

What are the components of the plasma membrane that can function as channels, carriers, receptors, and enzymes?

Membrane proteins

Phospholipid membranes form bilayers because their _ heads are attracted to water, while their _ tails face away from the water.

polar, nonpolar

The hydrophilic heads of phospholipids are exposed to water.

True Signup and view all the answers

The hydrophobic tails associate together and make up the interior of:

the membrane Signup and view all the answers

Note the plasma membrane's asymmetry.

Carbohydrate chains are attached to the outside surface and project into the extracellular matrix. Signup and view all the answers

Phospholipids are considered amphipathic molecules.

True Signup and view all the answers

What largely explains why phospholipids form a bilayer in water?

Their amphipathic nature Signup and view all the answers

Because similar substances associate with one another, what do the hydrophilic polar heads of phospholipid molecules associate with?

The polar water molecules Signup and view all the answers

The hydrophobic nonpolar tails associate with each other because:

They want to 'get away' from the polar water. Signup and view all the answers

Proteins that are embedded in the plasma membrane are called:

Integral proteins Signup and view all the answers

Proteins that occur only on the cytoplasmic side of the membrane are called:

Peripheral proteins Signup and view all the answers

Fluid-Mosaic Model: Membranes are not rigid but rather are:

Flexible structures Signup and view all the answers

Membranes consist of a variety of molecules, including:

Phospholipids, cholesterol, and proteins Signup and view all the answers

What does the fluid mosaic model represent?

The changing location and pattern of protein molecules in a fluid phospholipid bilayer. Signup and view all the answers

The lipid content of the membrane is responsible for:

Its fluidity Signup and view all the answers

Cells are flexible because the phospholipid bilayer is fluid.

True Signup and view all the answers

The greater the concentration of unsaturated fatty acid residues:

The more fluid the bilayer. Signup and view all the answers

Phospholipids and proteins that have attached carbohydrate chains are called:

Glycolipids Signup and view all the answers

Glycolipids are:

Lipids in plasma membranes that contain an attached carbohydrate chain. Signup and view all the answers

What are glycoproteins?

Proteins in plasma membranes that contain an attached carbohydrate chain. Signup and view all the answers

Each cell within an individual has its own 'fingerprint' because:

Of these carbohydrate chains. Signup and view all the answers

Glycolipids and glycoproteins play an important role in:

Cellular identification Signup and view all the answers

What are channel proteins?

Proteins that form a channel to allow a particular molecule or ion to cross the plasma membrane. Signup and view all the answers

Channel proteins are involved in:

Passing molecules through the membrane Signup and view all the answers

What are carrier proteins?

Proteins in the plasma membrane that combine with and transport a molecule or ion across the plasma membrane. Signup and view all the answers

What do carrier proteins do?

They receive a substance and change their shape, moving the substance across the membrane. Signup and view all the answers

A carrier protein transports sodium and potassium ions across the plasma membrane of:

A nerve cell. Signup and view all the answers

Without this carrier protein, nerve impulse conduction would be impossible.

True Signup and view all the answers

Cell recognition proteins are:

Glycoproteins Signup and view all the answers

Cell recognition proteins help the body defend itself against:

Pathogens Signup and view all the answers

What are receptor proteins?

Proteins located in the plasma membrane or within the cell that bind to a substance that alters some metabolic aspect of the cell. Signup and view all the answers

Study Notes

Plasma Membrane Composition

The plasma membrane consists of a phospholipid bilayer with embedded integral proteins and peripheral proteins associated with the cytoplasmic side.
Membrane proteins function as channels, carriers, receptors, and enzymes.

Phospholipid Bilayer Characteristics

Polar heads of phospholipids are attracted to water, while nonpolar tails orient away from water, forming the bilayer structure.
The hydrophilic heads face external and internal surfaces, while hydrophobic tails form the membrane's interior.

Membrane Asymmetry

Carbohydrate chains are present on the outside surface, projecting into the extracellular matrix, contributing to the membrane's asymmetry.

Amphipathic Nature of Phospholipids

Phospholipids have both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions, explaining their bilayer formation in aqueous environments.

Fluid-Mosaic Model

Membranes are flexible rather than rigid, consisting of varied molecules, including phospholipids, cholesterol, and proteins.
The fluidity of the membrane is influenced by lipid composition; higher unsaturated fatty acid concentration increases fluidity.

Glycolipids are lipids with attached carbohydrate chains, crucial for cell identity, synthesized in the Golgi apparatus.
Glycoproteins are integral membrane proteins featuring carbohydrate chains and also play a role in cellular recognition.

Protein Functions in Membranes

Integral proteins are embedded in the plasma membrane; peripheral proteins are located only on the cytoplasmic side.
Channel proteins form passages that allow specific molecules or ions to cross the membrane.
Carrier proteins transport specific molecules by changing shape after binding the substance.

Importance of Carrier Proteins

A carrier protein specifically transports sodium and potassium ions essential for nerve impulse conduction, critical for cell signaling and communication.

Cell Recognition Proteins

Glycoproteins function as cell recognition proteins, identifying the cell as 'self' and aiding in immune defense against pathogens.

Receptor Proteins

Receptor proteins in the membrane or within the cell bind to substances, initiating metabolic changes within the cell.

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Description

Explore the intricate structure and properties of the plasma membrane in this quiz. Learn about the phospholipid bilayer, membrane proteins, asymmetry, and the fluid-mosaic model. Test your understanding of how these components contribute to the cell's functionality.

Biology Chapter: Plasma Membrane Composition

Questions and Answers

What is the plasma membrane composed of?

What are the components of the plasma membrane that can function as channels, carriers, receptors, and enzymes?

Phospholipid membranes form bilayers because their _______ heads are attracted to water, while their _______ tails face away from the water.

The hydrophilic heads of phospholipids are exposed to water.

The hydrophobic tails associate together and make up the interior of:

Note the plasma membrane's asymmetry.

Phospholipids are considered amphipathic molecules.

What largely explains why phospholipids form a bilayer in water?

Because similar substances associate with one another, what do the hydrophilic polar heads of phospholipid molecules associate with?

The hydrophobic nonpolar tails associate with each other because:

Proteins that are embedded in the plasma membrane are called:

Proteins that occur only on the cytoplasmic side of the membrane are called:

Fluid-Mosaic Model: Membranes are not rigid but rather are:

Membranes consist of a variety of molecules, including:

What does the fluid mosaic model represent?

The lipid content of the membrane is responsible for:

Cells are flexible because the phospholipid bilayer is fluid.

The greater the concentration of unsaturated fatty acid residues:

Phospholipids and proteins that have attached carbohydrate chains are called:

Glycolipids are:

What are glycoproteins?

Each cell within an individual has its own 'fingerprint' because:

Glycolipids and glycoproteins play an important role in:

What are channel proteins?

Channel proteins are involved in:

What are carrier proteins?

What do carrier proteins do?

A carrier protein transports sodium and potassium ions across the plasma membrane of:

Without this carrier protein, nerve impulse conduction would be impossible.

Cell recognition proteins are:

Cell recognition proteins help the body defend itself against:

What are receptor proteins?

Study Notes

Plasma Membrane Composition

Phospholipid Bilayer Characteristics

Membrane Asymmetry

Amphipathic Nature of Phospholipids

Fluid-Mosaic Model

Carbohydrate-Related Molecules

Protein Functions in Membranes

Importance of Carrier Proteins

Cell Recognition Proteins

Receptor Proteins

Studying That Suits You

Description

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