Biology Chapter 5: Membrane Structure and Function practice flashcards

Comprehensive vocabulary flashcards covering membrane structure, transport mechanisms, protein diversity, and cell surface modifications based on the lecture outline.

Capsaicin

A substance found in hot peppers that binds to pain receptor proteins, causing $Ca^{2+}$ ions to move into the cell and signal pain to the brain.

Fluid mosaic model

A model of the plasma membrane structure where a phospholipid bilayer has a fluid consistency and proteins are scattered like icebergs in a sea.

Phospholipid bilayer

The foundation of the plasma membrane with hydrophilic polar heads lining the external and cytoplasmic surfaces and nonpolar, hydrophobic fatty-acid tails sandwiched in between.

Peripheral proteins

Membrane proteins that are found only on the inner membrane surface.

Integral proteins

Transmembrane proteins that are partially or wholly embedded in the plasma membrane.

Cholesterol

A lipid component of the plasma membrane that affects its fluidity.

Glycoproteins

Proteins with attached carbohydrate chains that contribute to the cell’s "fingerprint" and cellular identification.

Glycolipids

Lipids with attached carbohydrate chains found only on the outside of the plasma membrane, contributing to its asymmetry.

Channel Proteins

Proteins that allow molecules or ions to cross the plasma membrane freely via a channel; faulty $Cl^-$ channels cause Cystic fibrosis.

Carrier Proteins

Proteins that selectively interact with specific molecules or ions (like $Na^+ - K^+$) to assist their passage across the membrane.

Cell Recognition Proteins

Glycoproteins, such as MHC (major histocompatibility complex), that help the body recognize foreign substances and play a role in organ transplant rejection.

Receptor Proteins

Proteins shaped for specific molecule binding, such as growth hormone, allowing cells to respond to signals from other cells.

Enzymatic Proteins

Membrane proteins like adenylate cyclase that directly catalyze specific metabolic reactions.

Junction Proteins

Proteins that attach adjacent cells, such as tight junctions, allowing tissues to fulfill coordinated functions.

Signal transduction pathway

A series of relay proteins initiated by a signaling molecule binding to a receptor, leading to a specific cellular response.

Selectively permeable

A property of the plasma membrane that allows small, non-charged molecules like $CO_2$ and $O_2$ to cross freely while inhibiting others.

Aquaporins

Specialized proteins that speed up the transport of water across the plasma membrane.

Bulk transport

The movement of large particles into or out of the cell via vesicle formation, including exocytosis and endocytosis.

Diffusion

The net movement of molecules down a concentration gradient from high to low concentration until equilibrium is reached.

Osmosis

A special case of diffusion focusing on the movement of water across a selectively permeable membrane toward higher solute concentration.

Osmotic pressure

The pressure that develops in a system as a result of osmosis.

Isotonic Solutions

Solutions where solute and water concentrations are equal on both sides of the membrane, resulting in no net water movement.

Hypotonic Solutions

Solutions with a lower solute concentration than the cell, causing water to enter and results in turgor pressure in plants or lysis in animal cells.

Hypertonic Solutions

Solutions with a higher solute concentration than the cell, leading to water loss, crenation in animal cells, and plasmolysis in plant cells.

Facilitated Transport

Passive movement of molecules like glucose and amino acids across the membrane following a concentration gradient using specific carrier proteins.

Active Transport

The movement of molecules against their concentration gradient (low to high) requiring specific carrier proteins and the expenditure of ATP.

Sodium-potassium pump

An active transport carrier protein that uses ATP to move $3 \text{ Na}^+$ out of the cell and $2 \text{ K}^+$ into the cell.

Exocytosis

A form of bulk transport where a secretory vesicle fuses with the plasma membrane to release its contents outside the cell.

Phagocytosis

A type of endocytosis where cells engulf large, solid materials like debris or viruses into a vesicle.

Pinocytosis

A form of endocytosis, often called "cell drinking," where vesicles form around liquids or very small particles.

Receptor-Mediated Endocytosis

A specific form of pinocytosis using receptor proteins and coated pits to take in specific substances; defective in hypercholesterolemia.

Extracellular Matrix (ECM)

A meshwork of proteins and polysaccharides including collagen, elastin, fibronectin, and proteoglycans that surrounds animal cells.

Adhesion Junctions

Intercellular filaments between cells, such as desmosomes, that hold cells together.

Tight junctions

Junctions that join cells to form impermeable barriers, preventing material leakage between cells.

Gap Junctions

Joined plasma membrane channels that allow for communication and material passage between adjacent cells, crucial in heart muscle.

Plasmodesmata

Cytoplasmic strands that penetrate plant cell walls, allowing for the passage of material and communication between adjacent plant cells.