Membrane Structure Part Two: Diffusion, Osmosis, And More!

Question 1

Diffusion

Answer 1

The tendency for molecules of any substance to spread out evenly into the available space
Move from high concentration to low concentration
Driving force of movement of substances across cell membrane

Question 2

Concentration gradient

Answer 2

Substances diffuse dow their concentration gradient

The difference in concentration of a substance from one area to another

Question 3

Osmosis

Answer 3

Osmosis is the movement of water across a semipermeable membrane
The movement of water through cell membranes by facilitated diffusion

Question 4

Osmosis is affected by

Answer 4

the concentration gradient of dissolved substances

Question 5

Tonicity

Answer 5

The ability of a solution to cause a cell to gain or lose water
Has great impact on cells without walls

Question 6

Isotonic

Answer 6

Concentration of solutes is the same outside as it is inside the cell
There will be no net movement of water
Flaccid

Question 7

Hypotonic

Answer 7

Concentration of solutes is less outside than it is inside the cell, so the water concentration outside is greater
The cell will gain water and lyse (rupture of cell wall)
Turgid, healthy

Question 8

Hypertonic

Answer 8

Too much salt, not enough water
Concentration of solutes outside is greater than inside of the cell
Cell will lose water and shrivel
Flaccid

Question 9

Passive transport

Answer 9

The movement of materials across the membrane without using cellular energy is called passive transport

Question 10

Facilitated diffusion

Answer 10

Transport proteins speed the movement of molecules across the plasma membrane
Transport proteins

Question 11

Aquaporins

Answer 11

Inside of cells lipid bilayer is hydrophobic - water molecules have trouble passing through cell membrane
Water channel membranes, allow water to pass through

Question 12

Difference between osmosis and diffusion

Answer 12

Molecules that move in the case of osmosis are water molecules, not solute molecules

Question 13

Net movement

Answer 13

Net movement of water toward concentrated sugar solution - movement of water towards area of less concentration

Question 14

Active transport

Answer 14

The movement of materials against their concentration gradients is known as active transport (low conc. to high)
Requires energy
carried out by transport proteins
(sodium potassium pump)

Question 15

Bulk transport

Answer 15

Larger molecules and solid clumps of material can be transported by movements of the cell membrane known as bulk transport
Occurs by exocytosis
and endocytosis

Question 16

Channel proteins

Answer 16

Provide corridors that allow a specific molecule or ion to cross the membrane

Question 17

Carrier proteins

Answer 17

Undergo a conformational change to facilitate the passage of certain molecules into the cell

Question 18

Exocytosis

Answer 18

Transport vesicles migrate to the plasma membrane, fuse with it, and release their contents

Question 19

Endocytosis

Answer 19

The cell takes in macromolecules by forming new vesicles from the plasma membrane
Phagocytosis, Pinocytosis, Receptor mediated Endocytosis

Question 20

Phagocytosis

Answer 20

Cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole

Question 21

Pinocytosis

Answer 21

Endocytosis of extracellular fluid

Fluid itself is not needed by the cell, but the molecules dissolved in the substance

Question 22

Receptor mediated endocytosis

Answer 22

Enables the cell to acquire bulk quantities of specific substances
Molecule is sparse in fluid, With receptors the cell engulfs more of specific molecule than it would without