IB HL Biology- 2.1 Molecules to metabolism

lipid bilayers/ membranes function

membranes inside eukaryotic cells divide the cytoplasm into compartments

the basic structure is mostly the same in all cells

made of a sheet of amphipathic molecules called phospholipids

controls the passage of substances in and out of a cell

phospholipids

has a hydrophillic head and a 2 hydrophobic tails, creates a sheet for the membrance

permeability of molecules

the ability of a substance to allow gases or liquids to go through it

water passes easily through the membrane

the larger the molecule, the lower the permeability

the molecules are in random motion

diffusion

the spreading out of particles in liquids and gases that happens bc the molecules are in random motion

particles move from high concentration to low concentration

passive process, doesnt need energy

simple diffusion

particles passing between phospholipids in the membrane

non polar molecules move through easily

if the oxygen concentrarion inside a cell is reduced bc of aerobic respiration, oxygen will pass into the cell if the concentration of oxygen outside the cell is higher

integral proteins

embedded into the membrande, transmembrane protein, extends across the membrane

peripheral proteins

not embedded into the membrane, attached to the surface by a single hydrocarbon chain that attaches and embeds itself into the membrane

osmosis

the process in which molecules pass through a semi-permable membrane from a low concentration to a high concentration

aquaporins

proteins that increase membrane permability to water

channel proteins

an integral protein that with a pore that connects the cytoplasm to the aqueous solution outside the cell