phospholipid-bilayer around outside of cell’s cytoplasm semi permeable regulates what enters...
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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
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