Chapter 6: Cell Membranes Flashcards
a layer two molecules thick
bilayer
a thin layer of lipids and proteins, separates a cell from its surrounding
plasma membrane
form channels that allow selected polar molecules and ions to pass across a membrane
transport proteins
the plasma membrane identify a cell as part of the same individual or as foreign
recognition proteins
recognize and bind molecules from other cells that act as chemical signals, such as hormones
receptor proteins
bind cells together by recognizing and binding receptors or chemical groups on other cells
cell adhesion proteins
speed chemical reactions in membranes
enzymes
lipid molecules with carbohydrate groups attached
glycolipids
protein molecules with carbohydrate groups attached
glycoproteins
the carbohydrate groups of the cell surface glycolipids and glycoproteins form a surface coat
glycocalyx
proposes that the membrane consists of a fluid phospholipid bilayer in which proteins are embedded and float freely
fluid mosaic model
embedded in the phospholipid bilayer
integral proteins
held to membrane surfaces by noncovalent bonds
peripheral proteins
biological membranes are….?
selectively permeable
- diffusion through the lipid part of a biological membrane
- depends solely on molecular size and lipid solubility
simple diffusion
-diffusion of polar and charged molecules through transport proteins in the hydrophobic lipid bilayer
facilitated diffusion
integral membrane proteins that form hydrophilic channels in the membrane through which water and ions can pass
channel proteins
channel protein that transport water
aquaporins
- switch between open, closed, or intermediate states
- facilitate transport of ions (Na+, K+, Ca2+, Cl-)
gated channels
- bind pecific single olute and transport it across the lipid bilayer
- undergo conformational changes that move the solute -binding site from one side of the membrane to the other
- can become saturated when there are too few transport proteins to handle all the solute molecules
carrier proteins
