HumBio ch3: plasma membrane - passive transport

Cells retain their normal shape and exhibit no net loss or gain of water.

Glucose transport is usually unidirectional, moving from the blood into the cells.

1. The cell is the smallest unit of life. 2. All organisms are made of one or more cells. 3. Cells only arise from other cells.

Plasma membrane, cytoplasm, and nucleus.

From 2 micrometers to over a meter.

A lipid bilayer primarily made of phospholipids.

The polar hydrophilic heads face water, while the nonpolar hydrophobic tails line up in the center.

Kinetic energy.

A passive transport process where certain molecules move through the membrane via carrier proteins or channel proteins.

Proteins that are anchored to the membrane or to other proteins.

They contain a lower concentration of nonpenetrating solutes than cells, causing cells to plump up as water rushes in.

It is limited by the number of available protein carriers; when all are engaged, transport is saturated.

They allow ions and small molecules to pass from cell to cell, facilitating communication.

Both water and solute will enter the cell, causing it to swell and burst.

Greater concentration differences lead to more collisions and faster diffusion.

Channels that are controlled and can be opened or closed by chemical or electrical signals.

Lipid solubility and size of the substance.

The intrinsic kinetic energy of the molecules themselves.

The number of solute particles, not the type of solute.

Net diffusion of both solute and water occurs until equilibrium is reached.

A coating formed by carbohydrates on the outer surface of the cell.

They can move side to side and rotate, but rarely flip to the other layer.

50 to 100 trillion cells.

They form impermeable junctions that prevent molecules from passing between cells.

Metabolic energy, usually in the form of ATP.

Osmoles per liter (osmol/L).

Peripheral proteins are not embedded in the lipid bilayer and attach loosely to integral proteins or anchor into the membrane.

The ability of a solution to change the shape of cells by altering their internal water volume.

Specificity and saturability.

The movement of molecules or ions from an area of higher concentration to an area of lower concentration.

Simple diffusion, facilitated diffusion, and osmosis.

A state where molecules move equally in all directions with no net movement.

The plasma membrane, cytoplasm, and nucleus.

The diffusion of a solvent, usually water, through a membrane.

Cells lose water and shrivel, or crenate.

The activities of cells are dictated by their shapes and the types and relative numbers of subcellular structures they contain.

It determines which substances enter or exit the cell.

Transmembrane proteins that transport substances, usually ions or water, through aqueous channels.

They allow for rapid communication and coordination of heart contractions.

Because there is a maximum rate of transport due to a limited number of these proteins in the membrane.

Simple diffusion does not require a transport protein, while facilitated diffusion does.

Substances contributing to body mass found outside the cells.

Active transport and vesicular transport.

From an area of higher water concentration to an area of lower water concentration (or lower to higher solute concentration).

A process where substances bind to carrier proteins in the membrane and are ferried across, moving down their concentration gradient.

Desmosomes are anchoring junctions that prevent adjacent cells from separating.

A carbohydrate-rich area at the cell surface created by sugars of glycoproteins and glycolipids.

Loss of homeostasis underlies virtually every disease.

Because of its very small size, allowing it to diffuse through the membrane.

The fluid in tissues that bathes all cells.

It becomes permeable to virtually everything, allowing substances to flow freely in and out.

Glycoproteins are proteins with carbohydrates attached, and glycolipids are lipids with carbohydrates attached.

Cells are the structural units of all living things.

Specialized structures that allow neighboring cells to adhere and communicate.

Proteins firmly inserted into the lipid bilayer, some of which are transmembrane proteins that span the entire membrane.

They prevent molecules from passing through the extracellular space between adjacent cells.

Osmolarity is based on total solute concentration, while tonicity is based on how the solution affects cell volume.

Plasma membrane proteins interact with specific chemical messengers and relay messages to the cell interior.

They allow communication between adjacent cells through hollow cylinders called connexons.

They provide identity molecules that help in cell recognition.

Glycolipids are lipids with attached carbohydrates, while glycoproteins are proteins with attached sugars.

It stiffens the membrane by wedging between phospholipid tails.

Interstitial fluid, blood plasma, and cerebrospinal fluid.

It contains nutrients and substances that cells need to remain healthy.

Stiffens the membrane and decreases water solubility.

Integral and peripheral proteins.

It acts as a physical barrier, enclosing the cell and separating the cytoplasm from the extracellular fluid.

The diffusion of a solvent, such as water, through a selectively permeable membrane.

Acts as a selectively permeable barrier.

Because they can move more easily through the medium.

Controls cellular activities.

A model depicting the plasma membrane as a double layer of lipids with proteins dispersed throughout, forming a constantly changing mosaic pattern.

The total concentration of all solute particles in a solution.

They use them to recognize which cells belong in the body and which are foreign.

They can form channels for transport, act as carriers, enzymes, or receptors for signal transduction.

Concentration, molecular size, and temperature.

Channels that are always open, allowing ions or water to move according to concentration gradients.

Water moves and the volume changes, mimicking osmosis across plasma membranes.

Intracellular fluid packed with organelles.

The back pressure that develops as water diffuses into living cells, influencing cellular energy savings.

Active transport.

They allow the cell to communicate with its environment and make up about half of the plasma membrane by mass.

Cell recognition through carbohydrates.

Distilled water, which contains no solutes.

Substances that aid in digestion and act as lubricants, such as intestinal and gastric fluids, saliva, mucus, and serous fluids.

Epithelial cells are flat and tile-like, forming a barrier that protects underlying tissues.

Higher temperatures increase molecular movement and speed up diffusion.

Transmembrane proteins that allow single-file diffusion of water molecules.

The unassisted diffusion of lipid-soluble or very small particles across the membrane.

Prevent water-soluble substances from crossing, forming a boundary.

They allow cells to recognize 'who is who' during development and help immune cells identify pathogens.

A fluid mosaic model.

The watery environment outside the cell.

Inward-facing layer and outward-facing layer.

Passively or actively.

It may change almost continuously to evade immune system recognition.

The tendency of water to move into the cell by osmosis, equal to the hydrostatic pressure within the cell.

The process where substances diffuse directly through the lipid bilayer, typically small nonpolar molecules.

It acts as a selectively permeable barrier, allowing some substances to pass while excluding others.

Assisted diffusion of molecules through a membrane via carrier molecules or transport proteins.

Phospholipids.

The watery environment inside the cell.

The cell.

Anchoring junctions that bind adjacent cells together like molecular Velcro.

Mitosis.

The most abundant extracellular material, composed of proteins and polysaccharides that bind body cells together.

Animal cells swell or shrink due to net water gain or loss until solute concentration is equal on both sides of the membrane.

Plant cells have a rigid cell wall, while animal cells do not, affecting how they respond to water diffusion.

They provide temporary binding sites that guide cell migration and facilitate cell-to-cell interactions.

To move solutes across the membrane using energy.

They facilitate the diffusion of water through a selectively permeable membrane.

Integral proteins.

They differ in the kinds and amounts of lipids they contain, affecting local membrane structure and function.