Diffusion, Passive and Active Transport, Cell membrane

how does a sodium-potasium pump work?

3 sodium groups and a phosphate group bind to the pump. The pump then changes shape and releases the sodium outside the cell. two potassium ions bind to the pump, then the phosphate group is released and the potassium is released inside cell.

ion channel

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

concentration gradient

A difference in the concentration of a substance across a distance

isotonic solution

A solution with the same concentration of water inside a cell as outside the cell, no change in cell.

pinocytosis

A type of endocytosis in which the cell takes in fluid and its dissolved solutes.

phagocytosis

A type of endocytosis in which the cell takes in solids.

second messenger

Acts as a signal molecule in the cytoplasm

exocytosis

An active transport process by which materials are expelled from a cell by a vesicle binding with the cell membrane

cytolysis

Bursting of a cell due to hypotonic solution

endocytosis

Cell membrane forms a pouch around the substance. The pouch closes and pinches off from the membrane to form a vesicle inside the cell. the vesicle also bonds with lysosome so nutrients can be digested.

plasmolysis

Cell shrinks due to hypertonic solution

osmosis

Diffusion of water through a selectively permeable membrane

active transport

Energy-requiring process that moves material across a cell membrane against a concentration gradient

simple diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

facilitated diffusion

Movement of specific molecules across cell membranes through protein channels(ion channels, carrier proteins)

passive transport

Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient

contractile vacuole

The cell structure that collects extra water from the cytoplasm and then expels it from the cell.

How do polar molecules cross the cell membrane?

The use certain proteins to pass.

osmotic or turgor pressure

When vacuole in the plant cell swells with water and puts pressure on cell organelles. (hypotonic)

how does a carrier protein work?

a molecule outside the cell binds to carrier protein on cell membrane, where it then transports it across the cell membrane and is released inside the cell

what makes up the cell membrane?

a phospholipid bilayer that has different proteins embedded within it.

receptor protein

a protein that binds to a specific signal molecule, enabling the cell to respond to the signal molecules

hypertonic solution

a solution that causes the cell to shrink because the concentration of water outside the cell is lower than than the concentration inside the cell

hypotonic solution

a solution that causes the cell to swell because the concentration of water outside the cell is higher than the concentration inside the cell

equilibrium

a state where the concentration of a substance is equal through out the space

what is a phospholipid?

it has a phosphate group head that is polar and hydrophilic (likes water) and fatty acid tails that are non polar and hydrophobic (water fearing). they are connected by glycerol

how does an ion channel work?

it is a mode of transport in which ions can pass through. It is tube or doughnut shaped and allows ions to pass through when it is open. the ion gate however may close.

what polarity can pass through the membrane?

non polar substances can pass through

examples of active transport?

protein pumps, (sodium-potassium pump), endocytosis, exocytosis, contractile vacuole

examples of passive transport?

simple diffusion, protein channels, ion channels, facilitated diffusion

How does the cell membrane maintain homeostasis?

the cell membrane regulates what come into and out of the cell.

What are the factors that affect the rate/ability of diffusion?

the concentration gradient, the size of the molecule, temperature, charge

what determines the direction in which a substance diffuses across a membrane?

the substance moves down the concentration gradient

Why can't proteins and polysaccharides enter and leave the cell through membrane proteins?

they are too big

how do sodium-potassium pumps work?

they transport 3 sodium ions out and 2 potassium ions in

carrier proteins

transportation protien that carries a specific substance across a cell membrane