biochemistry chapter 8: biological membranes

What does the fluid mosaic model describe?

The dynamic structure of plasma membranes containing lipids, proteins, and carbohydrates.

What is the primary component of biological membranes?

Lipids, both by mass and mole fraction.

What do flippases do in the plasma membrane?

They maintain bidirectional transport of lipids between membrane layers.

What role do cholesterol molecules play in the membrane?

They contribute to membrane fluidity and stability.

What is the function of proteins in the cell membrane?

Act as transporters, adhesion molecules, and enzymes.

What type of proteins can have hydrophobic domains in the membrane?

Transmembrane proteins, which function as receptors or channels.

What do carbohydrates in the membrane form?

A protective glycoprotein coat and aid in cell recognition.

How do extracellular ligands interact with membrane receptors?

They bind to receptors that act as channels or enzymes.

What is the role of waxes in membranes?

Function in waterproofing and defense, mostly in plants.

What characterizes the fluid nature of the plasma membrane?

Lipids move freely in the plane and can form lipid rafts.

How does the fluid mosaic model visualize the membrane?

It depicts the membrane as a dynamic, semisolid structure.

What do embedded proteins in the membrane primarily involve?

Catalytic complexes or cellular communication.

How do moving lipids contribute to membrane dynamics?

They allow the membrane to adapt and fluidity.

In cell recognition, carbohydrates interact with what component?

They form a protective glycoprotein coat.

What do you find in low levels within the plasma membrane?

Triacylglycerols and free fatty acids.

What is a key characteristic of transmembrane proteins?

They often have multiple hydrophobic domains.

What do membrane-associated proteins typically act as?

Recognition molecules or enzymes.

Where can the fluid mosaic model be visualized?

In the dynamic structure of the plasma membrane.

What do proteins embedded in the membrane typically do?

Facilitate transport and communication.

Describe the overall function of biological membranes.

Ensure cellular integrity and regulate transport.

What type of model is used to describe membrane composition?

Fluid mosaic model.

What structural component replaces one fatty acid in glycerophospholipids?

A phosphate group.

Identify a primary mechanism facilitating lipid transport.

Flippases maintain lipid orientation.

What are the dynamic properties observed in the plasma membrane?

Movement of lipids, proteins, and carbohydrates.

What aids in forming lipid rafts in the membrane?

The lateral movement of lipids.

What type of proteins function in cell adhesion?

Membrane proteins that interact with the extracellular matrix.

Why are membranes described as dynamic structures?

Due to continual lipid and protein movement.

What is essential for membrane stability?

The presence of cholesterol.

What is a primary role of glycoproteins?

Cell recognition and signaling.

What is the fluid matrix of the membrane primarily composed of?

A phospholipid bilayer.

What is one function of transport proteins in membranes?

Facilitate the movement of substances across the membrane.

What is the significance of cellular communication in membranes?

It enables interaction with environmental signals.

Identify an important structural feature of biological membranes.

Presence of phospholipid bilayer and proteins.

How does diversity in membrane composition affect function?

It allows functional specialization within different cell types.

What regulates transport intracellularly and intercellularly?

Cell-cell junctions

What do gap junctions allow between adjacent cells?

Rapid exchange of ions and small molecules

What do tight junctions prevent?

Paracellular transport

What anchors layers of epithelial tissue together?

Desmosomes and hemidesmosomes

What helps determine appropriate membrane transport mechanisms in cells?

Concentration gradients

What is osmotic pressure?

Pressure applied to a solvent to prevent osmosis

What is often described as a 'sucking' pressure?

Osmotic pressure

What does passive transport not require?

Energy

What describes the diffusion of water across a selectively permeable membrane?

Osmosis

What uses transport proteins to move impermeable solutes?

Facilitated diffusion

What type of transport requires energy?

Active transport

What classifications can active transport be divided into?

Primary and Secondary

What are the two types of secondary active transport?

Symport and Antiport

What is pinocytosis?

Ingestion of liquid into the cell in vesicles

What is phagocytosis?

Ingestion of larger, solid molecules into the cell

What is the primary mechanism of membrane transport for small nonpolar molecules?

Simple diffusion

What occurs when equilibrium is achieved in simple diffusion?

Molecules move equally in all directions

What core concept explains biological membranes?

Fluid mosaic model

What maintains the membrane potential?

Sodium-potassium pump and Leak channels

Which equation is used to calculate the electrical potential created by one ion?

Nernst equation

What is the Goldman-Hodgkin-Katz voltage equation used for?

To calculate the resting potential of a membrane at physiological temperature

What is a characteristic of the outer mitochondrial membrane?

Highly permeable to metabolic molecules and small proteins

What enzyme cycle occurs in the inner mitochondrial membrane?

The citric acid cycle

Why does the inner mitochondrial membrane not contain cholesterol?

To maintain its specific function and structure in cellular respiration

What does the Goldman-Hodgkin-Katz voltage equation derive from?

The Nernst equation

Where are the electrons produced in the citric acid cycle used?

In the electron transport chain