Ch. 8 Biological Membranes

the fluid mosaic model accounts for

the presence of lipids, proteins, and carbohydrates in a dynamic, semisolid plasma membrane that surrounds cells

the plasma membrane contains proteins embedded within the

phospholipid bilayer

lipids move freely in the plane of the membrane and can assemble into

lipid rafts

flippases

specific membrane proteins that maintain the bidirectional transport of lipids between the layers of the phospholipid bilayer in cells

proteins and carbohydrates may also move within the membrane, but are slowed by their

relatively large size

the primary membrane component

lipids

_____ and __ ___ ___ act as phospholipid precursors and are found in low levels in the membrane

triacylglycerols, free fatty acids

_____ replace one fatty acid with a phosphate group, which is often linked to other hydrophilic groups

glycerophospholipids

_____ is present in large amounts and contributes to membrane fluidity and stability

cholesterol

____ are present in very small amounts; they are most prevalent in plants and function in waterproofing and defence

waxes

proteins within the cell membrane act as

• transporters

• cell adhesion molecules

• enzymes

______ proteins can have one or more hydrophobic domains and are most likely yo function as receptors or channels

transmembrane

_____ proteins are most likely part of a catalytic complex or involved in cellular communication

embedded

________ proteins may act as recognition molecules or enzymes

membrane-associated proteins

carbohydrates can form a protective ____ ____ and also function in cell recognition

glycoprotein coat

extracellular ligands can bind to membrane receptors, which function as

channels or enzymes in second messenger pathways

____ ____ regulate transport intracellularly and intercellularly

cell-cell junctions

____ junctions allow for the rapid exchange of ions and other small molecules between adjacent cells

gap

_____ junctions prevent paracellular transport, but DO NOT provide intercellular transport

tight

____ and ____ anchor layers of epithelial tissue together

desmosomes, hemidesmosomes

concentration gradients help to determine

appropriate membrane transport mechanisms in cells

_____ pressure, a colligative property, is the pressure applied top a pure solvent to prevent osmosis and is used to express the concentration of the solution

osmotic (aka → sucking pressure→ solution is drawing water in)

____ transport does not require energy because the molecule is moving down its concentration gradient (from an area with higher concentration to an area with lower concentration)

passive

____ diffusion does not require a transporter. Small, nonpolar molecules passively move from an area of high concentration to an area of low concentration until equilibrium is achieved

simple

osmosis

diffusion of water across a selectively permeable membrane

____ diffusion uses transport proteins to move impermeable solutes across the cell membrane

facilitated

_____ transport requires energy in the form of ATM or an existing favorable ion gradient

active

active transport may be ____ or ____ depending on the energy source

primary(uses ATP), secondary(uses gradient)

symport and antiport

• symport: both molecules going the same way

• antiport: both molecules going opposite ways

_____ and _____ are methods of engulfing material into cells or releasing material to the exterior of cells, both via the cell membrane

exocytosis, endocytosis

______ is the ingestion of liquid into the cell in vesicles formed from the cell membrane and _____ is the ingestion of larger, solid molecules

pinocytosis, phagocytosis

membrane potential is maintained by the

sodium-potassium pump and leak channels

electrical potential created by one ion can be calculated using the

Nernst equation

the resting potential of a membrane at physiological temperature can be calculated using the

Goldman-Hodgkin-Katz voltage equation

the _____ mitochondrial membrane is highly permeable to metabolic molecules and small proteins

outer

The ____ mitochondrial membrane has much more restricted permeability and surrounds the matrix, where the citric acid cycle produces electrons used in the electron transport chain and where any other enzymes important in cellular respiration are located

inner

does the inner mitochondrial membrane contain cholesterol

NO