Movement of substances into and out of the cell Cellular Transport: Movement of substances into and out of the cell Phagy X The Adventures of Osmosis Jones……..

All cells must exist in a liquid environment Water

Cellular transport is needed: -because the cell needs specific items -items needed to produce energy -through cell respiration -items needed to produce food -through photosynthesis - cell also needs to give off the waste it produces. Carbon Dioxide and water Oxygen and water

Two types of cellular transports: Passive Transport: Movement of substances into and out of a cell with NO extra energy required to be used by the cell. 3 Examples: -Diffusion -Osmosis -Facilitated diffusion

2.Active Transport: Movement of substances into and out of a cell but the cell must expend ATP energy in order to do so. -These items are either -very much needed - very dangerous -or too big to fit through the pores of the cell membrane 3 Examples: -Membrane Associated Pumps -Endocytosis -Exocytosis

In order for any substance to move into or out of the cell it must pass through what structure? Cell Membrane

Cell membranes are semi-permeable -certain items can move in and out of the cell and others can not. Items can move through the pores/openings between the phospholipids or through the proteins embedded in the bilayer.

Fluid Mosaic Model of the cell membrane/plasma membrane

Passive Transport Movement of substances into and out of the cell and the cell does not use any extra energy. All molecules have motion: Solids….molecules vibrate Liquid….have more energy so they have a little more motion Gas…… molecules have a lot of energy so they have much motion

It is the motion of the molecules that moves them through the membrane with passive transport.

Three forms of Passive Transport: Diffusion 2. Osmosis 3. Facilitated Diffusion All three move items into and out of cell with no extra energy required by the cell.

Diffusion -Form of passive transport. -Movement of any substance from a high concentration into a lower concentration.

High Low -Diffusion requires no extra energy. -Items move in or out due to the motion of the molecules. -molecules must be small enough to fit through pores or protein channels. -When molecules move from a high concentration into a lower concentration we say the item is moving down the concentration gradient. High Low

This is called a Dynamic Equilibrium If diffusion is the movement of any substance from a high concentration into a lower concentration then when will diffusion stop? When the concentration is equal on both sides…..no high or low remains. This is called a Dynamic Equilibrium

Example of diffusion in our body:

Simple Diffusion

The rate of diffusion can be increased by: 1. Increase in temperature 2. Increase in surface area 3. Stirring or shaking

Osmosis: -Form of passive transport Therefore requires no extra energy -Osmosis is the diffusion of water -Therefore the water must move from a high to a low concentration -The diffusion of water is given its own name, osmosis, because water is such an important substance for all living organism.

When will osmosis stop? When there is an equal amount of water on both sides of the membrane. This is called an osmotic balance.

Turgor Pressure

The direction of osmosis is controlled by the concentration of the solution located inside and outside the cell. Remember substances like water move from a high concentration to a low concentration. H L H L

Three types of solutions/environments for a cell: Hypotonic solution: Hypo = low A solution where the concentration of solute molecules outside the cell is lower than the concentration of solute molecules inside the cell.

Hypotonic Environment: 98% water 2% solute Water enters the cell. Turgor pressure increases. Cell swells in size. This is called cytolysis. 96% water 4% solute

2. Isotonic solution: Iso = equal A solution where the concentration of solute molecules outside the cell is equal to the concentration of solute molecules inside the cell.

Isotonic Environment: Water enters and leaves the cell at an equal rate. Turgor pressure remains constant. Cell remains the same in size. This is called homeostasis or osmotic balance. 96% water 4% solute 96% water 4% solute

3. Hypertonic solution: Hyper = high A solution where the concentration of solute molecules outside the cell is higher than the concentration of solute molecules inside the cell.

Hypertonic Environment: 94% water 6% solute Water leaves the cell. Turgor pressure decreases. Cell decreases in size. This is called plasmolysis. 96% water 4% solute

Elodea

1% Saline Elodea cell in a fresh water environment 1% solute dissolved In 99% water.

Elodea in a 6% Saline Solution 6% salt dissolved In 94% water

WHY DID THIS HAPPEN??????????????

Facilitated Diffusion -final form of passive transport -requires cell to use NO extra energy FACILITATE: -means to help DIFFUSION: -form of diffusion so……………… -items move from a high concentration into a lower concentration.

Facilitated Diffusion: -allows for the movement of important items that are too large to fit through the pores of the membrane from a high into a low concentration with the help of “carrier proteins”. Carrier proteins: due to their 3-D shape they are very specific, each helps only one type of molecule to pass through the membrane.

Role of Insulin as a carrier protein Insulin moves glucose across the membrane 100X faster than it would move if insulin is not present.

Active Transport -movement across the membrane BUT the cell must expend energy in order for it to occur. Examples: Membrane Associated Pumps MAPs Endocytosis Exocytosis

MAPs ~ Membrane Associated Pumps -energy driven protein motors that move specific types of solutes across the cell membrane against the concentration gradient. -from a low into a high concentration High Low -in order for the cell to expend energy to move items across there must be a “real” need. Items must be really, really needed or really, really toxic to the cell.

Two types of MAPs: 1. Calcium Pump 2. Sodium-Potassium Pumps The cell is only willing to pump these three items across the membrane.

Bones and teeth require a lot of calcium to remain strong Bones and teeth require a lot of calcium to remain strong. Therefore they must “hoard” large amounts of calcium. Calcium must move from a low concentration in our blood into a high concentration in the cells of both the teeth and the bones. H L H

Muscles require a lot of potassium and create a lot of sodium as a waste. Therefore they must “hoard” large amounts of potassium and get rid of the sodium. Both of these substances must move from a low concentration into a higher concentration. K+ Na+

Membrane Associated Pumps

Endocytosis Hyperlink Endo = IN Cyto = CELL Cell membrane surrounds and engulfs items taking them into the cell.

Three types of endocystosis: Phagocytosis: -Cell surrounds and engulfs solid items taking them into the cell. Examples: Amoeba: White Blood Cells

2. Pinocytosis: -Cell surrounds and engulfs substances dissolved in water, taking them into the cell.

3. Receptor-mediated Endocytosis: -items like hormones, vitamins and minerals attach to specific receptor proteins. Once attached the membrane pinches together taking the items in.

Endocytosis

Exocytosis: -Cell membrane opens up and forces items out of the cell. Hyperlink Exo = OUT Cyto= CELL -Cell membrane opens up and forces items out of the cell. Example: Contractile Vacuoles Anal pores

Types of Exocytosis: Excretion: -waste is forced out of the cell -mucus, sweat, tears….. 2. Secretion: -items made by the cell and needed in other places are forced out of the cell. -hormones, digestive enzymes, saliva

Exocytosis

Scenario If a bone cell is surrounded by 100 units of calcium and it has 50 units already stored in it what will occur? 75 / Finally, as many as possible of the 75 units of Ca+ will move in due to MAPs 100 units of Ca+ 25 units move in by diffusion 75 / 50 units of Ca+