Cell Vocab

Amphipathic

Contains hydrophilic and a hydrophobic region (ex. lipids)

Aquaporins

Protein channels in the cell membrane that facilitates osmosis, the diffusion of water across the membrane

Concentration Gradient

Region long which the density of a chemical either increases or decreases

Cotransport

Coupling of the downhill diffusion of one substance to the uphill transport of another against its own concentration gradient

Cristae

Infolding of the inner membrane of a mitochondrion; inner membrane houses electron transport chains and molecules of ATP synthase

Electrochemical Gradient

Diffusion gradient of an ion, affected by both the concentration difference of an ion across a membrane (chemical force) and the ion’s tendency to move relative to the membrane potential (electrical force)

Endocytosis

Cellular uptake of biological molecules and particulate matter vi formation of vesicles from the cell membrane

Exocytosis

Cellular secretion of biological molecules by the fusion of vesicles containing the with the plasma membrane

Facilitated Diffusion

Passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure

Flaccid

Limp. Lacking turgor (stiffness or firmness) as in a plant cell in surroundings where there is a tendency for water to leave the cell

Glycoproteins

Protein with 1+ covalently attached carbohydrate

Hypertonic

Cell loses water when surrounded by a solution

Hypotonic

Cell gains water when surrounded by a solution

Isotonic

No net movement of water when cell is surrounded by a solution

Ion Channel

A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient .

Lysosome

A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists .

Membrane Potential

The difference in electrical charge (voltage) across a cell’s plasma membrane due to the differential distribution of ions .

Sodium Potassium Pump

A transmembrane protein in animal cells that actively transports sodium ions (Na⁺) out of the cell and potassium ions (K⁺) into the cell, using ATP. This pump helps maintain the cell’s electrochemical gradient and proper osmotic balance.

Nuclear Envelope

In a eukaryotic cell, the double membrane that surrounds the nucleus .

Nucleoid

A non-membrane-enclosed region in a prokaryotic cell where its chromosome is located .

Osmoregulation

Regulation of solute concentrations and water balance by a cell or organism .

Peripher Proteins

A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer .

Peroxisome

An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen (O2), producing and then degrading hydrogen peroxide (H2O2) .

Phagocytosis

A type of endocytosis in which large particulate substances or small organisms are taken up by a cell .

Pinocytosis

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes .

Plasmodesmata

An open channel through the cell wall that connects the cytoplasm of adjacent plant cells, allowing water, small solutes, and some larger molecules to pass between the cells .

Plasmolysis

A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall, occurs when the cell loses water to a hypertonic environment .

Plastids

One of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts, found in the cells of photosynthetic eukaryotes .

Selective Permeability

A property of biological membranes that allows them to regulate the passage of substances across them .

Tonicity

The ability of a solution surrounding a cell to cause that cell to gain or lose water .

Tonoplast

A selective membrane that surrounds the central vacuole in plant cells, regulating the movement of ions and other solutes between the cytosol and the vacuole.

Transport Proteins

A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane .

Turgid

Swollen or distended, as in plant cells. A walled cell becomes turgid if it has taken up water .