5 Homeostasis + Cell Transport

Front 1

Active transport

Back 1

the movement of chemical substances, usually across the cell membrane, against a concentration gradient; requires cells to use energy

Front 2

concentration gradient

Back 2

a difference in the concentration of a substance across a distance

Front 3

contractile vacuole

Back 3

in protists, an organelle that accumulates water and then releases it periodically to maintain osmotic pressure

Front 4

diffusion

Back 4

the movement of particles from regions of higher density to regions of lower density

Front 5

endocytosis

Back 5

the process by which a cell membrane surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell

Front 6

equilibrium

Back 6

concentration of a substance is the same throughout a space

Front 7

exocytosis

Back 7

the process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out

Front 8

facilitated diffusion

Back 8

the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins

Front 9

hypertonic solution

Back 9

solute concentration is higher than the solute concentration inside a cell

Front 10

hypotonic solution

Back 10

solute concentration is lower than the solute concentration inside a cell

Front 11

isotonic solution

Back 11

solute concentration is equal to the solute concentration inside a cell

Front 12

ion channel

Back 12

a complex of protein molecules in a cell membrane that form a pore through which ions can pass

Front 13

osmosis

Back 13

water molecules diffuse across a cell membrane from an area of higher concentration to an area of lower concentration

Front 14

passive transport

Back 14

the movement of substances across a cell membrane without the use of energy by the cell (from high to low)

Front 15

pinocytosis

Back 15

a method of active transport across the cell membrane in which the cell takes in extracellular fluids (cell drinking)

Front 16

phagocytosis

Back 16

the process by which a cell engulfs large particles or whole cells, either as a defense mechanism or as means to obtain food (cell eating)

Front 17

sodium-potassium pump

Back 17

1. 3 sodium ions located in the cytosol bind to the carrier protein
2. a phosphate group is removed from ATP and bound to the carrier protein
3. the binding of the phosphate group changes the shape of the carrier protein, allowing the 3 sodium ions to be released into the cell's environment
4. 2 potassium ions located outside the cell bind to the carrier protein
5. the phosphate group is released, restoring the original shape of the carrier protein
6. the 2 potassium ions are released into the cytosol, and the cycle is ready to repeat.

Front 18

ATP (adenosine triphosphate)

Back 18

an organic molecule that acts as the main energy source for cell processes; composed of a nitrogenous base, a sugar, and three phosphate groups

Front 19

When molecules undergo passive transport, which way do they move?

Back 19

From high concentration to low concentration.

Front 20

When molecules undergo active transport, which way do they move?

Back 20

From low concentration to high concentration.

Front 21

What happens at equilibrium?

Back 21

The concentration of molecules is the same throughout the space. Even at equilibrium, the random movement of molecules continues, but equilibrium is still maintained.

Front 22

Which cellular transports rely on passive transport?
How do they accomplish this task?

Back 22

Diffusion and osmosis.
The substance moves from an area of high concentration to an area of lower concentration without the use of energy from ATP.

Front 23

Which cellular transports rely on active transport?
How do they accomplish this task?

Back 23

Endocytosis and exocytosis.
Endocytosis uses energy from ATP to ingest external fluid, macromolecules, and large particles. (The membrane folds inside around the particle and forms a pouch that pinches off inside the cell and forms a vesicle. The vesicle fuses with other organelles to be digested or used.) Exocytosis uses energy from ATP to release substances from the cell

Front 24

What do cells use for energy?
What would happen to a cell's ability to transport molecules if it did not have energy?

Back 24

ATP produced by the mitochondria.
The cell would only be able to use passive transport, which means it would not be able to eat or drink or remove certain things from itself.

Front 25

What do cells use the sodium-potassium pump for?

Back 25

it transports Na+ ions & K+ ions up their concentration gradients in animal cells because
animals need high concentration of Na+ inside and high concentration of K+ outside cells

Front 26

Why would some molecules need to use a carrier protein to enter or exit a cell?
Explain in terms of the phospholipid bilayer.

Back 26

Because they are too large to pass through the phospolipid bilayer.

Front 27

What is the difference between passive and active transport?

Back 27

Passive transport is the movement of a substance from an area of high concentration to an area of low concentration without energy. Active transport is the movement of a substance from an area of low concentration to an area of high concentration with energy.

Front 28

Explain hypertonic, hypotonic, and isotonic solutions in relationship to animal and plant cells.

Back 28

Hypertonic cells are cells that have very little water in them. In plant cells, they are called plasmolyzed.
Hypotonic cells are cells that swell up because they have a great amount of water. In plant cells, they are called turgid. Isotonic cells are at a state of equilibrium (the water is equal in and out of the cell). In plants, these cells are called flaccid.