Cell Transport PowerPoint Notes

Cell Membrane

A __***semipermeable***__ membrane that surrounds the cell and protects the cell’s components from the environment surrounding the cell.

The cell membrane consists of…

Lipids

Cell membranes contain several passage ways and pumps like..

protein pumps, aquaporins, glycoproteins, and sodium-potassium pumps

__***Intra***__cellular

area inside the cell membrane

__***Extra***__cellular

area outside the cell membrane

What does every cell have?

EVERY CELL HAS A CELL MEMBRANE!!!

Homeostasis

Stable Internal Environment (SIE)

Maintains homeostasis within the cell:

Communicates with other cells

Protects and supports the cell

Regulates what enters and leaves the cell

Selectively Permeable

Concentration gradients occur when…

There is a difference between the concentration of a substance on either side of the membrane

The water/liquid moves __***into***__ the cell when…

There is a higher concentration outside of the cell membrane than inside the cell.

The water/liquid moves __***out***__ of the cell when…

There is a higher concentration in the cell membrane than out of the cell.

When the solute concentration is equal inside and outside of the cell (Homeostasis, this is where we want to be)

Equilibrium

Molecules tend to move…

From a high concentration to low concentration. (Down the concentration gradient)

Moving __***down***__ the concentration gradient (High to low) requires…

No energy

Moving __***against***__ the concentration gradient (low to high) requires…

Energy

Cell transport helps cells:

Maintain homeostasis

Take in molecules needed for cell processes

Excrete cell waste

Passive transport is…

The transport of materials across the cell membrane without using energy

In passive transport materials move…

Move down the concentration gradient from a high to low concentration

Examples of Passive Transport:

Diffusion

Facilitated Diffusion

Osmosis

Diffusion is..

The movement of molecules from an area of high concentration to an area of low concentration

Molecules move directly through a ___ during diffusion

Cell Membrane

Diffusion is what kind of force?

Driving force behind the movement of many substances across the cell membrane

Molecules move…

Randomly and equilibrium is reached

Facilitated diffusion occurs when…

When molecules can’t directly diffuse across the membrane

What do molecules pass through instead of the membrane during facilitated diffusion?

Molecules pass through protein channels to cross the membrane

Ions and larger molecules (like glucose) use ____ to pass quickly through the cell membrane

protein channels

Facilitated diffusion is what kind of transport?

Passive Transport

During facilitated diffusion, substances move…

Down the concentration gradient, High to low concentration

Osmosis is…

The diffusion of water through a selectively permeable membrane.

Water moves ____ during osmosis

Down the concentration gradient from an area of high concentration to an area of low concentration (to the area of more solute)

Why do water molecules sometimes have a hard time passing through the cell membrane?

The cell membrane is hydrophobic

What are the protein channels that facilitates the diffusion of water across the membrane?

Aquaporins

Water moves through the membrane to reach…

Equilibrium on both sides of the cell membrane

The movement of water….

Equalizes the concentration of solute on both sides of the membrane. (Cell→Cell = Homeostasis)

The ___________ out or into the cell produces a force called osmotic pressure

Net movement of water

_____is a measure of the osmotic pressure gradient

Tonicity

Tonicity

Relative to the concentration of solutes dissolves in solution

Can cause cells to swell or shrink

Solutions can be isotonic, hypotonic, or hypertonic

In isotonic solutions, the concentration of the solutes is the____

same inside and outside the cell

In hypertonic solutions, the _____

solution has a higher solute concentration than the cell

Net Movement of water molecules out of the cell

The cell will shrink

In hypotonic solutions, the _____

solution has a lower solute concentration than the cell

Net movement of water molecules into the cell

The cell will swell

The opposite of passive transport is…

Active transport

Active transport is the…

Movement of substances across the cell membrane __***against***__ the concentration gradient

Requires energy (ATP)

Moves materials from low to high concentration

Two types

Molecular transport

Bulk Transport

Molecular transport is…

A type of active transport used to carry small molecules and ions across the membrane

Carried out by transport proteins called protein pumps

Use of energy allows the cell to concentrate substances in a specific location

Sodium - potassium pump

Powerful active transport proteins

Allows nerves to pass electrical charges so they can function

Transports sodium and potassium __***against***__ their concentration gradient

Bulk transport is…

A type of active transport used to carry large molecules or clumps of materials across the membrane.

Sometimes involves a change in the shape of the membrane

Facilitated by vesicles and vacuoles

In __***exo***__cytosis, materials…

exit the cell

Vacuoles containing materials fuse with cell membrane

Contents of vacuole leave the cell

Used for excretion of cell waste

In __***endo***__cytosis, materials…

Enter the cell

Pockets of material are folded in by the cell membrane to form a vesicle

Examples include:

Phagocytosis

Pinocytosis

Receptor-mediated

Phagocytosis is…

A type of endocytosis in which extensions of cytoplasm surrounded a particle and packaged it with a food particle

**Cell eating**

used by amoebas to take in food

used by white blood cells to eat damaged cells

Pinocytosis is…

A type of endocytosis in which tiny pockets form along the cell membrane and take in liquids

**Cell drinking**

In receptor mediated endocytosis…

Specialized receptor proteins in the membrane specify which substances are brought into the cell

Cells absorb metabolites, hormones, proteins, and sometimes viruses by the inward budding of the membrane

The receptors on the cell…

Identify the thing that’s entering the cell and determines how to let them get in