Movement of molecules into and out of a cell Cellular Transport Movement of molecules into and out of a cell Introduce with: paper towels…soak up water even if you just put a corner in water Perfume sprayed in one area…moves out to rest of area

Facts you should already know All particles are in constant random motion (KINETIC ENERGY) Particle in a solid move very slowly Gas particles move faster; liquids in between

Types of Cellular Transport Passive: requires no energy (ATP) Active: requires energy (ATP)

Three Forms of Transport Across the Membrane The Plasma Membrane 12/8/2018 copyright cmassengale G. Podgorski, Biol. 1010

3 Types of Passive Transport

1st type of Passive Transport: Diffusion Individual particles move from an area of higher concentration to an area of lower concentration

Diffusion Result of random movement of molecules

When the concentration of a substance is the same on one side of a membrane as it is on the other, the system is in balance--it has reached equilibrium.

Always constant movement but there’s no net change (concentration stays the same on both sides of the membrane) Called: Dynamic Equilibrium. Key things to understand: constant motion Equilibrium Dynamic equilibrium

What affects diffusion? Each lab group will be responsible for determining the effect of a different variable. Size of molecules Concentration of molecules Temperature of molecules

Rate of Diffusion Affected by: Size of molecules Proof? Concentration Gradient is the difference in concentration between two areas. The bigger the difference the faster diffusion will occur. Think of a ski slope and how fast you will go down. Size of molecules: bigger molecules mover slower such as starch that doesn’t even go in; small molecules such as water, oxygen,and other non-polar molecules can get across. Slat usually doesn’t diffuse because it has a charge. Temperature: the warmer it is the faster molecules move and that speeds up the random bouncing around of the molecules and thus diffusion.

Rate of Diffusion Affected by: Concentration of molecules (also called concentration gradient) Proof?

Rate of Diffusion Affected by: Temperature Proof?

2nd Type of Passive Transport: Osmosis Special type of diffusion – only for WATER Cells are 90% water Movement of water molecules through a selectively permeable membrane DOWN (with) concentration gradient It is mostly water molecules that move in and out of a cell…that is why we have a special name for it.

Diffusion across a membrane Semipermeable membrane The Plasma Membrane 12/8/2018 Osmosis Diffusion across a membrane Diffusion of water across a membrane Moves from HIGH water potential (low solute) to LOW water potential (high solute) Semipermeable membrane G. Podgorski, Biol. 1010

Examples of Water Movement

selectively permeable membrane Where is the greatest concentration of water? Where is the greatest concentration of water? 70% water 30% salt At the beginning water is more concentrated outside in the solution….therefore water will move into the bag until equilibrium is reached. At that point water molecules will continue to move …just at the same rate into and out of the bag. 100% distilled water selectively permeable membrane

selectively permeable membrane Water will into the cell. 70% water 30% salt 100% distilled water selectively permeable membrane

selectively permeable membrane What happens to the bag? The bag swells. If you put wilted flowers or a celery stalk in water, they will absorb the water and perk back up. Same idea with dehydrated food…put in water and it swells up. 100% distilled water selectively permeable membrane

selectively permeable membrane Where is the greatest concentration of water? 90% water 10% salt Water will flow out of the cell. Salt does not flow through the selectively permeable membrane. This causes cells to shrink. During hot summer when plants wilt this is what has happened. Leaving food out and it gets dry…. 80% distilled water selectively permeable membrane

3rd Type of Passive Transport: Facilitated Diffusion Movement of molecules that are too large to pass through a selectively permeable membrane Uses transport proteins Fast, specific, occurs with gradient Think of this as an insect coming into a room thru a hole in a window screen.

Three Types of Solutions describes amount of solutes Relative to inside of cell Solution Cell

Isotonic Solution Concentration of dissolved substances is the same inside the cell as the solution it is in Water molecules move…usually not the dissolved substances These cells are in dynamic equilibrium. No net gain or loss

Hypertonic Solution Concentration of dissolved substances is higher inside the solution (less water molecules outside) If you call someone “hyper” they have too much energy! Hyper means more here also….A solution is hypertonic if it has more of the dissolved substance than the cell. EX; a solution is 15% sugar and the cell is 1% sugar. There is more sugar in the solution…it is a hypertonic solution. Now think of the water..the solution would have 85% water and the cell would be 99% water. Water will move out of the cell. Water leaves the cell- this process is called Plasmolysis

Hypotonic Solution Concentration of dissolved substances in the solution is lower than on the inside (more water molecules on outside) Water will move into the cell to try to equalize the balance (dissolved substances can’t move) When you use the word solution  you are referring to what the cell is in. EX: a solution has 1% salt ( and thus 99% water) and the cell is 5% salt and 95% water. The solution has a lower concentration of salt…hypotonic solution. Now look at the water concentration…water is higher on the outside in the solution and lower on the inside….water will move in…causing the cell to swell. Cells swell up (“O” in hypotonic) Pressure inside is called turgor pressure, good in plants, bad in animal cells

Slug Vacation Disasters

selectively permeable membrane Water flows from the beaker into the bag. 70% water 30% salt Salt does not flow through the selectively permeable membrane. This is an example to test your understanding. 100% distilled water selectively permeable membrane

selectively permeable membrane What happens to the bag? The bag swells. This means the solution is hypotonic. 100% distilled water selectively permeable membrane

selectively permeable membrane What happens to the bag? 90% water 10% salt Example to test your understanding. 80% distilled water selectively permeable membrane

selectively permeable membrane What happens to the bag? The bag shrinks. This means the solution is hypertonic. 80% distilled water selectively permeable membrane

3 Types of Solutions Add to your “Incredible Egg” booklet the names of the solutions each egg was submerged in