Chapter 6

These flashcards cover key concepts related to cell membrane structure, function, and transport mechanisms from Chapter 6 of Bio 213.

What is the composition of cell membranes?

Cell membranes are composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates.

What are the components of a phospholipid?

A phospholipid consists of a hydrophilic 'head' (phosphate group) and two hydrophobic 'tails' (fatty acids).

What does selectively permeable mean in the context of cell membranes?

It means that some substances can pass through the membrane while others cannot.

What types of molecules can pass through cell membranes?

Small nonpolar and small uncharged polar molecules can pass through; large, charged, or polar molecules are excluded.

Describe the fluid mosaic model of cell membranes.

The fluid mosaic model describes the cell membrane as a dynamic, flexible structure made up of various components that can move laterally.

What are adhesion proteins and their role?

Adhesion proteins mediate cell-to-cell or cell-to-matrix attachment.

What is the function of transport proteins?

Transport proteins facilitate the movement of molecules across cell membranes.

What do receptor proteins do?

Receptor proteins bind to specific molecules and initiate a cellular response.

What is the role of recognition proteins?

Recognition proteins help cells identify and interact with each other.

Define concentration gradient.

Concentration gradient is the difference in the concentration of a substance between two areas.

What is diffusion?

Diffusion is the process of random movement of molecules toward equilibrium.

Define equilibrium in a biological context.

Equilibrium is a state of balance and stability within a biological system.

What factors influence rates of diffusion?

Factors include concentration gradient, temperature, and surface area.

How does temperature affect diffusion rates?

Higher temperature increases kinetic energy, which increases the rate of diffusion.

What is simple diffusion?

Simple diffusion is where molecules move directly through the membrane down their concentration gradient.

What is facilitated diffusion?

Facilitated diffusion is when molecules diffuse with the aid of protein channels or carriers along their concentration gradients.

What is endocytosis?

Endocytosis is the process where cells bring substances into the cell by folding inwards to form a vesicle.

What is exocytosis?

Exocytosis is the process where materials packaged in vesicles are secreted from the cell.

How do osmosis and diffusion differ?

Osmosis is the diffusion of water across a semipermeable membrane, while diffusion is the movement of any substance from high to low concentration.

Define tonicity.

Tonicity is the ability of a solution to alter the volume of a cell by affecting the net osmosis of water.

What is a hypotonic solution?

A hypotonic solution has a lower solute concentration relative to another solution.

What is a hypertonic solution?

A hypertonic solution has a higher solute concentration relative to another solution.

What is an isotonic solution?

An isotonic solution has an equal solute concentration compared to another solution.

What are tight junctions?

Tight junctions ensure directional movement and create a watertight seal between cells.

What are desmosomes?

Desmosomes provide strong adhesive connections between cells, acting like spot welds.

What are gap junctions?

Gap junctions allow communication between cells through channels.

What is a uniporter?

A uniporter moves one substance in one direction across the membrane.

What is a symporter?

A symporter moves two substances in the same direction across the membrane.

What is an antiporter?

An antiporter moves two substances in opposite directions across the membrane.