Ch.7: Membrane & Movement of Molecules

Question 1

Amphipathic molecules

Answer 1

contains hydrophobic and hydrophillic regions

Question 2

Cholesterol (steroid) acts as a

Answer 2

temperature buffer. Warm temps, it restrains movement, cool temperatures, it maintains fluidity within the cell membrane

Question 3

Peripheral proteins
Integral Proteins

Answer 3

Peripheral proteins are bound to the surface of the membrane. Hydrophilic

Integral Proteins penetrate the hydrophobic core.

Question 4

Diffusion

Answer 4

is the tendency for molecules to spread out into available space. Does not require energy called passive transport

Question 5

concentration gradient

Answer 5

Substances diffuse from high to low concentration, down their concentration gradient

Question 6

Osmosis

Answer 6

is the diffusion of water across a selectively permeable membrane.

Question 7

Isotonic solution:

Answer 7

Equal solute/water concentration as inside of the cell. No net water movement across the membrane.

Question 8

Tonicity

Answer 8

the ability of a solution to cause a cell to gain or lose water

Question 9

Hypertonic solution

Answer 9

Solute concentration is greater than inside the cell. Cell loses water. Cells shrivel

Question 10

Hypotonic solution:

Answer 10

Solute concentration is less than that inside the cell. More water, less solute., gains water.

Question 11

Osmoregulation

Answer 11

the control of water balance for life to survive., for ex: single celled organisms like protists.

Question 12

Facilitated diffusion

Answer 12

transports proteins and speeds the passive movement of molecules across the membrane.

Question 13

Channel proteins

Answer 13

like aquaporins (for water) facilitate the passage of molecules or ions through a hydrophilic channel that acts as a tunnel.

Question 14

Carrier proteins

Answer 14

bind to molecules and change shape to shuffle them across the membrane. Specific for the substance it moves.

Question 15

Active transport

Answer 15

moves substances against the concentration gradient, from LOW to HIGH concentration. REQUIRES ENERGY, ATP. Not equalibrium ex. Sodium-potassium pump

Question 16

Membrane potential

Answer 16

the voltage difference across a membrane. -

The inside of the cell has a negative charge.

Question 17

Electrogenic pump

Answer 17

a transport protein that generates voltage across a membrane

Question 18

Proton pump

Answer 18

is found in plants, fungi, and bacteria. (animals have sodiumpp)

Question 19

vesicles

Answer 19

Large molecules like polysaccharides and proteins cross the membrane in bulk via vesicles

Question 20

Exocytosis

Answer 20

when transport vesicles migrate to the membrane, fuse with it, and release their contents

Question 21

Endocytosis

Answer 21

The cell takes in macromolecules by forming vesicles from the plasma membrane.

Question 22

Phagocytosis

Answer 22

is a cell engulfing a particle in a vacuole. formes food vacuoles

Question 23

Pinocytosis

Answer 23

molecules taken up thru extracellular fluids being gulped up into tiny vesicles

Question 24

receptor mediated endocytosis

Answer 24

binding of ligands to receptors triggers vesicle formation

Question 25

ligand

Answer 25

any molecule that binds specifically to a receptor site of another molecule