Diffusion, Osmosis and Active transport

Table of Contents 1. Enzyme Notes 2. Enzyme lab pre & post questions (2 stamps) 3. Catalase lab data collection and rough draft 4. Notes on Enzyme Activity 5. Notes on Transport (p. 182-187) and class notes 6. Tape-In Cell membrane exploration. 7. Tape-In Keeping a balance 8. Tape-In Diffusion and Osmosis 9. Carrot Lab observations and data 10. Tape-In Solutions (Stamp) 11. Tape-In In –n- Out 12. Carrot Lab (4 stamps) 13. Osmosis Analysis Quiz (Stamp) 14. Rate “Per”fection page 1 15. Active Transport notes and WS (stamp)

Cellular Transport Unit

Passive Transport = movement of substances across the cell membrane without any input of energy by the cell

Passive Transport

TypesDiffusion = movement of molecules

from high to low [ ] (concentration)- driven by the concentration gradient

- spreads out evenly till dynamic equilibrium is reached

This Movement is the result of Kinetic Energy of the molecules

Diffusion

2) Osmosis = diffusion of water

A solution may be one of the following: (compared to a cell)

- isotonic solution: same [ ] of water and solute

- hypotonic solution: lower [ ] of solute, a lot of water

- hypertonic solution: higher [ ] of solute, less water

Isotonic Solution (Red Blood Cells)

A solution is isotonic to a cell if it has the same concentration of solutes as the cell. Equal amounts of water enter and exit the cell, so its size stays constant.

Hypotonic Solution (Red Blood Cells)

A hypotonic solution has fewer solutes than a cell. Overall, more water enters a cell in a hypotonic solution, causing the cell to expand and even burst.

Hypertonic Solution (Red Blood Cells)

A hypertonic solution has more solutes than a cell. Overall, more water exits a cell in a hypertonic solution, causing the cell to shrivel and even die

Direction of OsmosisOutside the Cell Inside the Cell Net Movement of

Water

Isotonic Isotonic None Hypotonic Hypertonic Inside the Cell Hypertonic Hypotonic Outside the Cell

** If the solution outside the cell is hypotonic, then inside the cell is hypertonic and vice versa** Water tends to diffuse from hypotonic to hypertonic

- Plasmolysis = cells shrink when turgor pressure is lost- the reason plants wilt

- Cytolysis = cell bursts due to water entering the cell

How do freshwater organisms deal with osmosis? What would be the problem?

Water would diffuse into the cells

What would organisms do to deal with the problem?Pump water out or excrete large amounts of

water

How do marine organisms deal with osmosis? What would be the problem?

Water would diffuse out of the cells

What would organisms do to deal with the problem?Pump water in or excrete large amounts of

salt into their tissues

How do they do this?Contractile Vacuole!

FullEmpty

Contractile Vacuole in action

3) Facilitated Diffusion

= move molecules across the cell membrane through carrier/transport proteins

- are specific for the type of molecule they help diffuse

Facilitated Diffusion (Open Channels)

Facilitated Diffusion (Proteins Change Shape)

Diffusion vs. Facilitated Diffusion Diffusion Facilitated Diffusion

Overview Passive Transport

DiffusionOsmosisFacilitated Diffusion

Active TransportProtein PumpBulk Transport

○ EndocytosisPinocytosisPhagocytosis

○ Exocytosis

Active Transport = substances can cross the cell membrane with an input of energy from the cell

The movement of molecules is AGAINST the concentration gradient. ( From low concentration to high concentration)

Active Transport

1) Endocytosis = the process by which cells ingest “stuff”

- vesicle holds the “stuff”

- two types:

1) pinocytosis - solutes and fluids

2) phagocytosis - large particles or whole cells

Endocytosis

2) Exocytosis = the process by which cells release “stuff”

- is essentially the reverse of endocytosis

Exocytosis

ACTIVE TRANSPORT – requires energy input (ATP) Protein Pumps Bulk Transport

Endocytosis – two types: phagocytosis and pinocytosis

Exocytosis

AnimationAnother animation

HOMEOSTASIS AND TRANSPORT              

  I. Cell MembranesA. Cell membranes help organisms maintain

homeostasis by controlling what substances may enter or leave cells

B. Some substances can cross the cell membrane without any input of energy by

the cell

C. The movement of such substances across the membrane is known as passive

transport

D. To stay alive, a cell must exchange materials such as food, water, & wastes with its

environment

E. These materials must cross the cell or plasma membrane

                                                       

                                         

F. Small molecules like water, oxygen, & carbon dioxide can move in and out freely

G. Large molecules like proteins & carbohydrates cannot move easily across the plasma membrane

H. The Cell Membrane is semipermeable or selectively permeable only allowing certain molecules to pass through

II. Diffusion

A. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration

http://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.html

B. Small molecules can pass through the cell membrane by a process called diffusion

C. Diffusion across a membrane is a type of passive transport because it does not require energy

D. This difference in the concentration of molecules across a membrane is called a concentration gradient

E. Kinetic energy keeps molecules in constant motion causing the molecules to move randomly away from each other in a liquid or a gas

The rate of diffusion depends on temperature, size of the molecules, & type of molecules diffusing

H. Molecules diffuse faster at higher temperatures than at lower temperatures

I. Smaller molecules diffuse faster than larger molecules

J. Most short-distance transport of materials in and out of cells occurs by diffusion

K. Solutions have two parts --- the solute which is being dissolved in the solvent

L. Water serves as the main solvent in living things

M. Diffusion always occurs down a concentration gradient (water moves from an area where it is more concentrated to an area where it is less concentrated)

http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

N. Diffusion continues until the concentration of the molecules is the same on both sides of a membrane

O. When a concentration gradient no longer exists, equilibrium has been reached but molecules will continue to move equally back & forth across a membrane

http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

Osmosis Think back to solutions:

solutes and solvents Osmosis is the process by which water

molecules diffuse across a cell membrane from an area of lower solute concentration to an area of higher solute concentration.

Direction of movement depends on relative concentrations of solutions.

Direction of movement into cells Hypotonic to the cytosol

solution outside the cell is less concentrated than inside the cell

water moves into the cell

Hypertonic to the cytosol solution outside the cell is more concentrated than inside the cell water moves out of the cell

Isotonic concentrations are equal

http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

Red blood cells are placed into 3 different types of solutions: figure out the types of solution in the beakers by looking at the RBC

ISOTONIC HYPOTONICHYPERTONIC

How do freshwater organisms deal with osmosis? What would be the problem?

Water would diffuse into the cells

What would organisms do to deal with the problem?Pump water out or excrete large amounts of

water

How do marine organisms deal with osmosis? What would be the problem?

Water would diffuse out of the cells

What would organisms do to deal with the problem?Pump water in or excrete large amounts of

salt into their tissues

How do they do this?Contractile Vacuole!

Finish the statements Diffusion is… Osmosis is… A hypertonic solution has… A hypotonic solution has… A cell placed in a hypertonic solution will… A cell placed in a hypotonic solution will… Both osmosis and diffusion are _______

transport because they do not require _______.

Passive Transport – no energy input required Diffusion Osmosis Facilitated Diffusion

Carrot Lab Advice

Your goal is to experimentally find the best isotonic solution for carrots.

How? set up 4-5 baggies with carrots and different concentrations of salt solutions to leave over night.

You will have to figure out what the appropriate solutions should be and..

how to properly make those solutions.

Some Lab tips

Dab your carrot with a paper towel before you weigh it so you are not weighing the excess water.

Be sure to use the electronic balance appropriately otherwise you will get incorrect data.

Be meticulous about recording all materials, procedures and data collected.

Using and electronic balancehttp://youtu.be/wyHDFCVrsM8

Today: (Thu/Fri) Tape-In and Check page 3/Procedures How good am I at writing procedures? Decide how much salt and how much

water you will put in each baggie Calculate the percent solution for each

baggie Revise carrot lab procedures Set up baggies and label

Hypothetical Carrot Lab Data

Change in mass

Percent Silinity

0% 0.25% 0.5% 0.75% 1%

0.35 g 0.16g -0.02g -0.26g -0.40g

Facilitated diffusion

Carrier Proteins: located in membrane

* Channels (always open)

* Gated channels (open when needed)

ACTIVE TRANSPORT – requires energy input (ATP) Protein Pumps Bulk Transport

Endocytosis – two types: phagocytosis and pinocytosis

Exocytosis

Active transport – Protein pumps