HumBio ch3: plasma membrane - passive transport

The watery environment outside the cell.

Cells are the structural units of all living things.

The watery environment inside the cell.

Specialized structures that allow neighboring cells to adhere and communicate.

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

50 to 100 trillion cells.

Inward-facing layer and outward-facing layer.

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

Cells lose water and shrivel, or crenate.

Integral and peripheral proteins.

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

Passively or actively.

The cell.

Cell recognition through carbohydrates.

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

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

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

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

Metabolic energy, usually in the form of ATP.

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

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

Anchoring junctions that bind adjacent cells together like molecular Velcro.

Distilled water, which contains no solutes.

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

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

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

Osmoles per liter (osmol/L).

It determines which substances enter or exit the cell.

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

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

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

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

Desmosomes are anchoring junctions that prevent adjacent cells from separating.

Mitosis.

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

Concentration, molecular size, and temperature.

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

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

Plasma membrane, cytoplasm, and nucleus.

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

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

They allow for rapid communication and coordination of heart contractions.

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

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

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

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

Greater concentration differences lead to more collisions and faster diffusion.

From 2 micrometers to over a meter.

Specificity and saturability.

Acts as a selectively permeable barrier.

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

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

It may change almost continuously to evade immune system recognition.

They provide identity molecules that help in cell recognition.

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

A lipid bilayer primarily made of phospholipids.

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

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

Because they can move more easily through the medium.

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

Intracellular fluid packed with organelles.

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

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

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

Lipid solubility and size of the substance.

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

Simple diffusion, facilitated diffusion, and osmosis.

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

Loss of homeostasis underlies virtually every disease.

Higher temperatures increase molecular movement and speed up diffusion.

Controls cellular activities.

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

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

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

It stiffens the membrane by wedging between phospholipid tails.

The intrinsic kinetic energy of the molecules themselves.

Kinetic energy.

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

Substances contributing to body mass found outside the cells.

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

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

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

Active transport.

To move solutes across the membrane using energy.

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

Interstitial fluid, blood plasma, and cerebrospinal fluid.

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

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

The plasma membrane, cytoplasm, and nucleus.

Active transport and vesicular transport.

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

The fluid in tissues that bathes all cells.

The total concentration of all solute particles in a solution.

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

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

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

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

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

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

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

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

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

Phospholipids.

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

Stiffens the membrane and decreases water solubility.

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

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

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

A fluid mosaic model.

Integral proteins.

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

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