Ch. 4 Cell Permeability and Transport

Question 1

Cholesterol (3)

Answer 1

• rigid ring lipid
• random throughout hydrophobic region
• gives plasma membrane structural strength

Question 2

Carbohydrate chains (3)

Answer 2

• extend from the outside of plasma membrane
• attached to proteins or phospholipids
• functions: signal, coating, or receptor

Question 3

Extracellular environment (3)

Answer 3

• outside of cell
• aqueous (contains water)
• extracellular fluid

Question 4

Lipid bilayer (3)

Answer 4

• made of two rows of phospholipid molecules
• phosphate group head faces outward
• fatty acid tails face inward

Question 5

Phosphate group head (4)

Answer 5

• part of the phospholipid molecule
• contains phosphate group
• polar and hydrophilic

Question 6

Fatty acid tails (4)

Answer 6

• part of the phospholipid molecule
• tails made of two fatty acid chains
• non polar and hydrophobic

Question 7

Peripheral protein (2)

Answer 7

• does not extend across lipid bilayer

- anchor point for cytoskeleton

Question 8

Transmembrane proteins (2)

Answer 8

• extend through lipid bilayer

- serve as transport protein or channel across bilayer

Question 9

Cytoplasm (4)

Answer 9

• inside cell
• aqueous (contain water)
• contains organelles
• intracellular fluid

Question 10

Diffusion (3)

Answer 10

• substances cross the membrane
• solute moves from area of high concentration to low concentration (down concentration gradient)
• passive

Question 11

Kinetic energy (2)

Answer 11

• driving force for passive transport mechanisms

- random collisions of molecules

Question 12

Simple diffusion (2)

Answer 12

• water, oxygen, and steroid hormones freely cross the cell membrane
• molecules move down their concentration gradient

Question 13

Facilitated diffusion (3)

Answer 13

• molecules are assisted by a channel or transport protein to cross the cell membrane
• ions, glucose, and amino acids
• molecules move down their concentration gradients

Question 14

Osmosis (3)

Answer 14

• selectively permeable membrane
• if concentration of two solutions is different, a concentration gradient exists for both water and the solute
• each substance attempts to diffuse down its concentration gradient

Question 15

Aquaporins

Answer 15

water is freely permeable through these channels

Question 16

Hypotonic solution (3)

Answer 16

• side with the lower solute concentration
• higher water concentration
• net movement of water out of this side

Question 17

Hypertonic solution (3)

Answer 17

• side with higher solute concentration
• lower water concentration
• net movement of water toward this side

Question 18

Equilibrium (2)

Answer 18

• molecules become evenly distributed and in equal concentrations on either side of the membrane
• dilute hypertonic solution to reach equilibrium

Question 19

Isotonic (4)

Answer 19

• equal solute and solvent concentration
• no further net movement from one side of the membrane to the other
• no net change in the concentration
• water will continue crossing membrane

Question 20

Osmosis (rule of thumb)

Answer 20

water will always move from hypotonic solution toward the hypertonic solution to make solution isotonic

Question 21

Osmotic pressure (2)

Answer 21

• pressure generated within cell as water presses against the plasma membrane
• cells change shape as water moves into or out of cell

Question 22

Isotonic solution cell shape

Answer 22

cell does not change shape

Question 23

Hypotonic solution cell shape

Answer 23

water diffuses into cell, swells up, potentially bursts

- net flow of water in red blood cell

Question 24

Hypertonic solution cell shape

Answer 24

water diffuses out of cell, cell will shrink or crenate

- net flow of water out of red blood cell

Question 25

Filtration (2)

Answer 25

• separation of particles in a solution when pressure is applied to one side of a membrane
• results in passage of small particles through membrane while larger particles unable to pass through are left behind

Question 26

Hydrostatic pressure

Answer 26

pressure is exerted by water flow
- ex. kidneys, hydrostatic pressure exerted by blood flow pushes water and small particles out of bloodstream to form urine (large particles including cells and large proteins remain in blood)

Question 27

Filtration rate

Answer 27

-rate that substances filter through the membrane

Question 28

Active processes

Answer 28

require energy in the form of ATP to drive the movement across the plasma membrane

Question 29

Active transport

Answer 29

transport of substances against concentration gradient (low concentration to high concentration)

Question 30

Endocytosis

Answer 30

bulk amounts of substances are taken into the cell by modifying plasma membrane structure

Question 31

Exocytosis

Answer 31

substances released from the cell into the extracellular environment

Question 32

Phagocytosis (3)

Answer 32

• process of cell eating
• intake of large substances into the cell followed by internal digestion by cellular enzymes
• requires cell’s plasma membrane to change its shape in order to surround large substance and engulf it into the cytoplasm

Question 33

Phagosome (2)

Answer 33

• membrane sac that forms around the substance in phagocytosis
• fuses with a lysosome to digest it

Question 34

Phagocytosis in human body

Answer 34

bacteria and dead cells are removed by specialized white blood cells

Question 35

Pinocytosis

Answer 35

uptake of small droplets of extracellular fluid

Question 36

Solvent

Answer 36

water is universal solvent

Question 37

Solutes

Answer 37

dissolved in water

- ex. sugars, proteins, electrolytes, and organic molecules

Question 38

Plasma membrane (3)

Answer 38

• primarily composed of lipids
• hydrophobic
• selectively permeable membrane