unit 3-2

__Cell Membrane__

regulates what enters and leaves the cell and also provides protection and support

__lipid bilayer__

1)    The cell membrane is composed of a __---__- form a tough, flexible barrier between the cell and its surroundings.

__Passive transport__

movement of materials from an area of high concentration to an area of low concentration. Does not require energy.

__Active Transport__

movement of materials from an area of low concentration to an area of high concentration. Requires energy

solutes

Those substances dissolved in water are called

__concentration__

The __----__of a solution is the amount, or %, of solute in a solution.

__diffusion__.

Therefore, molecules tend to move from an area of high concentration to an area of low concentration, which is known as

__passive transport__.

Diffusion causes substances to move, but does not require energy. It is a form of

__equilibrium__

Diffusion will occur until the cell reaches __---__, or there are equal amounts of the substance both inside and outside the cell.

__selectively permeable__

The cell membrane is __----__ which means that some substances can pass through and others cannot.

Water

is one substance which can pass through the membrane.

__Osmosis__

the movement of water molecules from an area of high concentration to an area of low concentration until

__Hypertonic__

when the solution has a higher concentration of solute and a lower concentration of water compared to another solution or the other side of the cell membrane

__Hypotonic__

when the solution has a lower concentration of solute and a higher concentration of water compared to another solution or the other side of the cell membrane

__isotonic__

When both the inside and outside of the cell have reached equilibrium, the cell is

__facilitated diffusion.__

The movement of large molecules from an area of high concentration to an area of low concentration until equilibrium is reached is called

concentrations.

Often times, materials move against a concentration difference, or from low to high

__active transport__

1)    These types of transports are known as __---__ because they require energy.

__Sodium – potassium pump__

type of active transport where proteins pump Na+ ions out of the cell and K+ ions into the cell.

__Endocytosis__

process of taking materials into the cell through infoldings, or pockets, of the cell membrane.

__Phagocytosis__

When large particles are taken into the cell. Extensions of the cytoplasm surround and engulf large particles

__Pinocytosis__

when water is taken into a cell through pockets of the cell membrane.

__Exocytosis__

the removal of large amounts of materials out of the cell.

vacuole

A vacuole with waste materials will fuse with the cell membrane and get rid of those waste products.

protein channels

There are also --- embedded in the cell membrane which allow larger molecules to pass in and out of the cell

cytoplasm

The ---- of a cell is composed of water and many other substances which are dissolved in water

solution

In a , molecules are moving constantly and tend to spread out so that they are evenly spaced

substance

If a is able to diffuse across the cell membrane, the membrane is permeable to that substance

glucose

Some molecules can pass directly through the cell membrane. Others, such as glucose, cannot because they are too large

molecules

These --- must move through protein channels in order to get in and out of the cell.