AP Bio Ch 7 Vocab

Active Transport

The movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy

Aquaporin

channel proteins that greatly facilitate the passage of water molecules through the membrane

Concentration gradient

an increase or decrease in the density of a chemical substance in an area -cells often maintain concentration gradients of ions across their membranes

Diffusion

The passive movement of molecules from a region of higher concentration to lower concentration: down the concentration gradient

Endocytosis

Active transport type that moves particles into a cell by enclosing them in vesicles from the plasma membrane

Exocytosis

The active transport process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out

Facilitated diffusion

Passive transport of substances through the cell membrane with the help of transport proteins (channel/carrier)

Fluid mosaic model

The cell membrane is a dynamic structure with a “mosaic” of various proteins embedded in or attached to a fluid bilayer of phospholipids which moves laterally

Gated channels

A protein channel in a cell membrane that opens or closes in response to a particular stimulus

Glycolipids

Important in cell-cell recognition; form when carbohydrates bond covalently to lipids

Glycoproteins

Important in cell-cell recognition; form when carbohydrates bond covalently to proteins

Hypertonic

The concentration of solute in the cell is less than that of the environment. Water will move out of the cell into the environment. (high solute outside the cell)

Hypotonic

The concentration of solute in the cell is greater than that of the environment. Water will move into the cell from the environment. (low solute outside the cell)

Integral protein

Penetrate the hydrophobic core of the lipid bilayer (embedded in the cell membrane) and many are transmembrane proteins which completely span the membrane. 2 kinds: hydrophobic and hydrophilic

Isotonic

The concentration of solute in the cell and the environment is the same. No net water movement (equillibrium)

Ligands

a general term for any molecule that binds specifically to a receptor site of another molecule

Osmosis

Diffusion of water; requires an aquaporin protein

Passive transport

The diffusion of a substance across a membrane with no energy investment (ATP not used)

Peripheral protein

Not embedded in the lipid bilayer, instead are appendages loosely bound to the surface of the membrane

Phagocytosis (cell eating)

Cell engulfs a particle by wrapping pseudopia around it and packaging it within a vacuole. The particle is digested after the vacuole fuses with a lysosome

Pinocytosis (cell drinking)

The cell “gulps” droplets of extracellular fluid into tiny vesicles

Proton pump

The main electrogenic pump of plants, fungi, and bacteria which actively transports hydrogen ions (protons) out of the cell

Selective permeability

Allows some substances to cross more easily than other substances

Transport proteins

Proteins that help specific ions and polar molecules avoid contact with the lipid bilayer/cross it. 2 types: channel (door) and carrier (confusing doors)