2.1.5 Biological Membranes Flashcards
Membrane
A thin layer of organelles acting as a boundary which controls movement in and out of the cell.
Partially permeable
Allows small molecules of water and certain solutes but does not allow others and big molecules.
Cell signalling
Communication between cells that coordinates actions e.g tissue repair.
Fluid mosaic model
The structure of the plasma membrane as a mosaic of components —including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character. Plasma membranes range from 5 to 10 nm in thickness.
Diffusion
The movement of molecules from an area of high concentration to an area of low concentration through a semipermeable membrane.
Facilitated diffusion
Spontaneous passive transport of small molecules and ions through diffusion across a membrane.
Active transport
The movement of molecules across a membrane from an area of low concentration to an area of high concentration against the concentration gradient.
Endocytosis
The taking in of matter by a living cell by invagination of its membrane to form a vacuole.
Exocytosis
Cell transports secretory products through cytoplasm to plasma membrane.
Osmosis
Diffusion of water across membrane from area of high conc to area of low conc.
Channel protein
Protein that allows the transport of specific substances across cell membrane.
Carrier protein
Proteins that carry substances from one side of the membrane to the other for molecules too big.
Phospholipid
A lipid containing a phosphate group in its molecule.
Lipid soluble
Small molecules such as O2 and CO2 can dissolve in the phospholipid and diffuse across the membrane.
Bilayer
Two molecules (lipids) that have a hydrophilic head and a hydrophobic tail.
Glycoprotein
Antigens for cell recognition.
Glycolipid
Provides energy and serves as a marker for cellular recognition.
Intrinsic
Across both layers, some are carriers, transporting water-soluble substances.
Extrinsic
On either surface of bilayer. Provides structural support and recognition sites.
Cholesterol
Maintains structure of the membrane.
Compartmentalisation
How organelles work in separate areas within the cell in order to to perform their functions efficiently.
Hydrophilic
Is attracted to water.
Hydrophobic
Is repelled by water.
Solvent
A liquid in which solutes are dissolved in forming a solution.
Cytolysis
Cell bursts.
Crenation
Cell shrivels.
Hydrostatic pressure
Pressure exerted at equilibrium.
Water potential
Pressure exerted by water as it collides with the membrane.
Kilopascals
Measurement of pressure.
