CELL MEMBRANE

CELL MEMBRANE

Phospholipid-bilayer Around outside of cell’s cytoplasm Semi permeable

Regulates what enters and leaves the cell. Maintains Homeostasis

Protects and supports the cell.

DIFFUSION

movement of molecules from high to low [ ] (concentration)

spreads out evenly until equilibrium is reached

WHICH MOLECULES WILL DIFFUSE IN EACH OF THE FIGURES BELOW?

1 2 3 4

5 6

ANSWERS

1 2 3 4

5 6

No Movement

No Movement

CELL MEMBRANE (VIDEO)

movement of substances across the cell membrane without any input of energy (ATP) by the cell

HIGH [ ] to low [ ]

PASSIVE TRANSPORT

SIMPLE DIFFUSION

Ion Channels & Facilitated

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

are specific for the type of molecule they help diffuse

ION CHANNELS

FACILITATED DIFFUSION (PROTEINS CHANGE SHAPE)

ACTIVE TRANSPORT

substances can cross the cell membrane with an input of energy (ATP) from the cell

Low [ ] to HIGH [ ]

PROTEIN PUMP

ENDOCYTOSIS

the process by which cells ingest “stuff” using vesicles

Exocytosis

the process by which cells release “stuff” (reverse of endocytosis)

NOTEBOOK PAGE

MEMBRANE INVESTIGATION

Materials: (per group of two students) 1 plastic bag 1 pair of scissors 15 cm of string 1 token per student

The Problem:Get the token into the bag according to the following rules: The token must enter through a solid part of the bag. The inside of the bag may not be directly open to the external

environment. The token entering the bag must remain clustered together. You may have your hands in the bag to act as the inside of a cell.

ENDOCYTOSIS AND EXOCYTOSIS (BULK TRANSPORT)

http://www.youtube.com/watch?v=DuDmvlbpjHQ

Exocytosis by parameciumhttp://

www.youtube.com/watch?v=U9pvm_4-bHg Endocytosis by amoeba

http://www.youtube.com/watch?v=W6rnhiMxtKU&list=PL_JrQv0cdUS_Pn4zUe2THWfMS1YHxyxL8

OSMOSIS : DIFFUSION OF WATER

OSMOSIS and DIFFUSION

Osmosis = diffusion of water

A solution may be one of the following:

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

isotonic solution: same [ ] of water and solute

hypertonic solution: higher [ ] of solute, less water

Hypotonic – The solution on one side of a membrane where the solute concentration is less than on the other side. Hypotonic Solutions contain a low concentration of solute relative to another solution.

Hypertonic – The solution on one side of a membrane where the solute concentration is greater than on the other side. Hypertonic Solutions contain a high concentration of solute relative to another solution.

ELODEA CELLSAs viewed under the microscope

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

OSMOSIS LAB

CARROT OSMOSIS- PG. 99

We will be putting one baby carrot in a small amount of distilled water and another in a small amount of saturated salt water (NaCl).

We will be recording their initial and final masses, and observing any textural changes.

Hypothesis: What do you think will happen to each of these carrots?

CARROT OSMOSIS

Data: Day 1: Mass of each carrot

Weighing boat needs to be clean and dry Texture/qualitative observations of each

carrot

NOTES ON SECTION 7.3 (PG. 97 & 98) Osmosis and Diffusion

0PENER 1/28 – PG. 101

1. Compare and contrast osmosis and diffusion.

2. Where is osmosis most likely to occur? Diffusion?

CARROT LAB ANALYSIS

1. Do you think osmosis occurred? What is your evidence?

2. Draw a picture of how you think water moved into or out of the carrots in each solution (distilled water and salt water).

DIFFUSION LAB

1. Obtain one cellulose bag and tie one end in a knot.2. Put 10 mL of starch solution in the bag.3. Tie other end of bag securely with a string.4. Dry the bag. This is now your “cell.”5. Place 10 drops of iodine in a beaker.6. Add approximately 150 mL of tap water to the beaker.7. Observe the color of the “cell” and record its

appearance.8. Place the “cell” in the 150 mL beaker.9. Observe and record any differences after 15

minutes

DIFFUSION LAB ANALYSIS

1. Did diffusion occur? If so explain which molecules moved and why.

2. Was the dialysis tubing a selectively permeable membrane? If so, explain and provide evidence for how you came to this conclusion.

CELL INTERVIEW

Write a script for interviewing a cell including the following: Series of creative, content-based questions Interview a cell about maintaining

homeostasis Supply the cell’s answers to the questions