Lesson 2 - Cell membranes Flashcards
meaning organelles
subcellular bodies found in the cytoplasm of cells
meaning eukaryotes
group of organisms with cells that have the genetic material contained in a membrane-bound nucleus and also contains many membrane-bound organelles
meaning prokaryotes
group of organisms including bacteria that have few organelles and do not have the genetic material contained in a membrane-bound nucleus
meaning cell surface membrane
the membrane that forms the outer boundary of the cytoplasm of a cell and controls the movement of substances into and out of the cell
meaning vesicles
membrane bags that hold secretions made in cells
meaning polar lipids
lipids with one end attached to a polar group
meaning gated channels
protein channels through the lipid bilayer of a membrane that are opened or closed, depending on conditions in the cell
meaning fluid mosaic model
a model of the structure of the cell membrane, including floating proteins forming pores, channels and carrier systems in a lipid bilayer
what are the 2 functions of the cell membrane
-controls what passes into and out of the cell
-allows the fluids either side of the cell membrane to have different compositions
describe the structure of a unit membrane
phospholipid molecules that form a bilayer with their hydrophilic heads pointing into the water, while the hydrophobic tails stay protected in the middle
which particles does the lipid bilayer allow to pass through
fat-soluble organic molecules
how do unsaturated fatty acids affect the membrane
the more unsaturated fatty acids, the more kinks in the fatty acids, so the less tightly packed the phospholipids are, so the more the fluid the membrane is
how do gated channels allow particles across the membrane
either use energy to move particles across, or contain hydrophilic channels which allow ionic substances through
