BI110 Lecture 9- Chapter 4: Cell Membranes and Signalling

These flashcards cover key vocabulary terms and definitions related to cell membranes and signaling from the lecture notes.

Selectively Permeable Membranes

Membranes that allow certain molecules or ions to pass while blocking others.

Impermeable Membranes

Membranes that do not allow any molecules or ions to pass through.

Phospholipids

Lipid molecules that form the bilayer of cell membranes, consisting of hydrophilic heads and hydrophobic tails.

Fluid Mosaic Model

A model describing the structure of cell membranes as a mosaic of various components that move fluidly.

Integral Proteins

Proteins that are embedded in the membrane and can span across it.

Peripheral Proteins

Proteins that are not embedded but are attached to the exterior or interior surfaces of the membrane.

Hydrophilic

Substances that are attracted to water and can easily dissolve in it.

Hydrophobic

Substances that repel water and do not dissolve in it.

Osmosis

The diffusion of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration.

Passive Transport

Movement of substances across a membrane without the use of energy.

Active Transport

Movement of substances across a membrane that requires energy (usually ATP) to occur.

Concentration Gradient

The difference in concentration of a substance across a space.

Endocytosis

The process through which a cell takes in materials by engulfing them in a membrane.

Exocytosis

The process of vesicles fusing with the plasma membrane to release contents outside the cell.

Receptor-Mediated Endocytosis

A type of endocytosis that involves the uptake of specific molecules based on receptor-ligand interactions.

Signal Transduction

The process by which a cell converts an extracellular signal into a functional response.

Cell Communication

Systems that allow cells to perceive and respond to their environment.

Amplification in Signaling

The process in which a small number of signal molecules can lead to a large cellular response.

Second Messenger

A molecule that relays signals received at a receptor on the cell surface to target molecules inside the cell.

Phosphorylation Cascade

A series of enzyme-catalyzed reactions in which a signal is amplified by adding phosphate groups to proteins.

Epinephrine

A hormone that triggers the body's 'fight or flight' response, increasing blood glucose levels.

Hydrophobic Effect

The tendency of hydrophobic molecules to minimize their exposure to water, resulting in molecular aggregation.

Fluidity of Membrane

The ability of the lipid bilayer in a membrane to allow lateral movement of lipids and proteins.

Desaturases

Enzymes that introduce double bonds into fatty acids, impacting the fluidity of membranes.

Sterols

Lipids that stabilize and maintain membrane fluidity across varying temperatures.

Facilitated Diffusion

A type of passive transport that uses membrane proteins to help move substances across the membrane.

Cotransport

A mechanism of membrane transport whereby two solutes are transported simultaneously across the membrane.

Primary Active Transport

Transport process that uses ATP directly to move molecules against their concentration gradient.

Secondary Active Transport

Transport process driven indirectly by energy from primary active transport.

Na+/K+ Pump

An active transport mechanism that moves sodium out of and potassium into the cell against their concentration gradients.

Signal Molecule (Ligand)

A molecule that binds to a receptor to initiate a cellular response.

Hydration Shell

The sphere of water molecules that surrounds and interacts with a solute.

Membrane Buffers

Molecules, like sterols, that help maintain membrane integrity and fluidity.

Amoeba Proteus

A single-celled organism that utilizes phagocytosis for nutrient intake.

Clathrin

A protein that coats the cytoplasmic side of the plasma membrane involved in receptor-mediated endocytosis.

Isotonic Solution

A solution where the concentration of solute is equal inside and outside the cell, resulting in no net movement of water.

Hypertonic Solution

A solution with a higher concentration of solute compared to another solution, causing cells to lose water.

Hypotonic Solution

A solution with a lower concentration of solute compared to another solution, causing cells to gain water.