Cell Transportation Test

Cell transport

all of the various mechanism by which cells move materials in and out across the cell membrane

Diffusion

molecules move/spread out from where there is more of them to where there is less of them (high to low)

Concentration Gradient

conceptual state of a substance in which one side has a high concentration and the other has a low concentration

Concentration gradient moving high to low

needs no energy

Passive transport

does not require energy input from a cell

Examples of passive transport

simple diffusion, facilitated diffusion, and osmosis

Osmosis

the diffusion of water molecules across a semipermeable membrane

Three types of solutions

hypertonic, hypotonic, isotonic

Hypertonic

more solute, less water

Hypotonic

more water, less solute

Isotonic

same amount of both

Way water moves in osmosis

hypotonic area to hypertonic area

Cell membrane is made of 

two phospholipid layers, other molecules embedded into membrane

Two functions of cell membrane

-forms a boundary between inside and outside of cell

-controls passage of materials

Examples of active diffusion

endocytosis, exocytosis, and the sodium-potassium pump

Facilitated diffusion

transport of polar substances or ions across a semipermeable membrane that requires transport proteins

Transport proteins in facilitated diffusion are called

channel proteins and carrier proteins

Chanel proteins

simple tunnels that molecules can use to enter or exit the cell, can be gated to open and close

Carrier proteins

proteins that change their shape after interacting with a specific molecule in order to let it pass through

Active transport

moves substances across the cell membrane AGAINST the concentration gradient (from low to high)

Active transport

is used to move very large molecules that will not fit through the membranes or the transport protein

Active transport is used

to move very large molecules

Endocytosis

substances that are too large can enter the cell through this process

Exocytosis

substances that are too large to exit the cell use this process

Passive transport moves

down the concentration gradient (from high to low)

Active transport moves

up/against the concentration gradient (from low to high)

Facilitated diffusion

diffusion of water polar or charged molecules across a semipermeable membrane using transport proteins

Sodium potassium pump

active transport of 3 sodium ions out of the cell and 2 potassium ions in the cell to maintain an electrical gradient in neurons

Larger cells have a

larger surface area: volume ratio

Smaller cells have a

smaller surface area: volume ratio