Ch 8: Biological Membranes

Question 1

Fluid Mosaic Model

Answer 1

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

Question 2

Phospholipid bilayer

Answer 2

plasma membrane contains proteins embedded within this

membrane is not static

Question 3

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

Answer 3

lipid rafts

Question 4

Flippases

Answer 4

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

Question 5

Proteins and carbohydrates may also move within the membrane but are slowed

Answer 5

by their relatively large size

Question 6

Lipids are the ___ membrane component, both by ___ and ___

Answer 6

primary
mass
mole fraction

Question 7

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

Answer 7

triacylglycerols

free fatty acids

Question 8

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

Answer 8

glycerophospholipids

Question 9

present in large amounts and contributes to membrane fluidity and stability

Answer 9

cholesterol

Question 10

present in very small amounts, if at all; they are most prevalent in plants and function in waterproofing and defense

Answer 10

waxes

Question 11

acts as transporters, cell adhesion molecules, and enzymes

Answer 11

proteins

Question 12

can have one or more hydrophobic domain and are most likely to function as receptors or channels

Answer 12

transmembrane proteins

Question 13

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

Answer 13

embedded proteins

Question 14

may act as recognition molecules or enzymes

Answer 14

membrane-associated proteins

Question 15

____ can form a protective ____ and also function in cellular recognition

Answer 15

carbohydrates

glycoprotein coat

Question 16

Extracellular ligands can bind to _____ which function as channels or enzymes in _____

Answer 16

membrane receptors

second messenger pathways

Question 17

regulate transport intracellularly and intercellularly

Answer 17

cell-cell junctions

Question 18

gap junctions

Answer 18

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

Question 19

tight junctions

Answer 19

prevent paracellular transport, but do not provide intercellular transport

Question 20

___ and ___ anchor layers of epithelial cells

Answer 20

desmosomes

hemidesmosomes

Question 21

concentration gradients

Answer 21

help to determine appropriate membrane transport mechanisms in cells

Question 22

osmotic pressure, a colligative property,

Answer 22

is the pressure applied to a pure solvent to prevent osmosis and is used to express the concentration of the solution

often better conceptualized as “sucking” pressure in which a solution is drawing water in, proportional to its concentration

Question 23

passive transport

Answer 23

does not require energy because the molecule is moving down its concentration gradient or from an area of high concentration to an area of lower concentration

Question 24

simple diffusion

Answer 24

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

Question 25

osmosis

Answer 25

describes diffusion of water across a selectively permeable membrane

Question 26

facilitated diffusion

Answer 26

uses transport proteins to move impermeable solutes across the cell membrane

Question 27

active transport

Answer 27

requires energy in the form of ATP or an existing favorable ion gradient

can be primary or secondary depending on the energy source

Question 28

secondary active transport can be further classified as ___ and ___

Answer 28

symport

antiport

Question 29

endocytosis and exocytosis are

Answer 29

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

Question 30

pinocytosis

Answer 30

ingestion of liquid into the cell from vesicles formed from the cell membrane

Question 31

phagocytosis

Answer 31

ingestion of bacteria by phagocytes

Question 32

membrane potential

Answer 32

maintained by sodium-potassium pump and leak channels

Question 33

Nernst equation

Answer 33

electrical potential created by one ion can be calculated using this

Question 34

Goldman-Hodgkin- Katz voltage equation

Answer 34

resting potential of a membrane at physiological temperature can be calculated using this, which is derived from Nernst

Question 35

Mitochondrial membrane differs from the cell membrane in that

Answer 35

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

Question 36

the inner mitochondrial membrane surrounds the ____ where the citric acid cycle produces electrons used in the electron transport chain and where many other enzymes important to ____ are located. The inner mitochondrial membrane also does not contain ____

Answer 36

mitochondrial matrix
cellular respiration
cholesterol