1. Happy Monday!! Bellwork:
Draw a copy of the picture below. Use your drawing to explain why it is important for cells to be small.

2. Activity: Set up PAGE #12 for Cornell Notes
Title this page “Cell Membrane Observations”
Your first entry on the left hand side should be “Observations”.
You should all have a set of random objects at your tables.
For the next 7 minutes you will explore and record as many observations as you can about the items at your table. (CHAMP)
Write down ANYTHING you observe.
There are no right or wrong answers.

3. Today’s Essential Question
What is a membrane and what is it’s purpose?
What did you observe in the activity and how does it relate to the essential question?

4. All cells are surrounded by a thin, flexible barrier known as a cell membrane.

5. What is the cell membrane’s function (job)? (2 things)

6. The two main functions are: 1) to regulate what enters and leaves the cell 2) to provide protection and support.

7. Membranes fall into three categories…
They can be permeable, meaning that the membrane is penetrable and will allow liquids, particles and gasses to pass through it.
Which of the objects from the activity were completely permeable?

8. They can be impermeable, meaning that the membrane is not penetrable and will NOT allow liquids, particles or gasses to pass through it.
Which of the objects from the activity were completely impermeable?

9. Finally, they can be Selectively permeable, meaning that some substances can pass across while others cannot.
Biological membranes, like the ones around your cells, are selectively permeable.
Which of the objects from the activity were selectively permeable?

10. What is the cell membrane composed (made) of? (3 types of molecules)

11. The cell membrane is composed of a double-layered sheet called a lipid bilayer.
Bi- means 2
carbohydrate
DRAW THIS!
Lipid
Phosphate
Also called the phospholipid bilayer

12. Proteins are embedded in the lipid bilayer.
Proteins form channels or pumps that help move large materials across the cell membrane.

13. Carbohydrates are attached to many proteins embedded on the outside of the bilayer.
The carbohydrates allow individual cells to identify one another.

15. HW #3 Regular Biology (Periods 4 & 5) Tonight’s Homework…
Page 13 of your I.A.N. in Cornell Notes
There are several ways to access the homework video:
Search “Molecule Alyssa Dolny” on YouTube
Go to my website and click on the “Lessons and Assignments” link

16. vocabulary
Cell Membrane Function Permeable Impermeable Selectively Permeable (Semi- Permeable) Phospholipid Bilayer Hydro Phobic Phillic

17. The concentration is the amount of a substance dissolved into water.

18. A concentration gradient is a difference between two concentrations.
Diffusion is the movement of particles down the concentration gradient.
High Concentration
Crystal Light Commerical
Low Concentration

19. When the concentration of a solute is the same throughout a system, the system has reached equilibrium.
When equilibrium is reached, particles do continue to move across the membrane.

20. When particles move from an area of high concentration to an area of low concentration.
This is known as diffusion.

21. Diffusion of WATER through a selectively permeable membrane is called osmosis.
Remember: SALT SUCKS

22. Isotonic means “same strength”. Hypertonic means “above strength”
Isotonic means “same strength”. Hypertonic means “above strength”. Hypotonic means “below strength”.
Draw This
Label: Hypotonic
Water: High (outside cell)
Solute: Low
Label: Hypertonic
Water: Low (outside cell)
Solute: High
Label: Isotonic
Water: Same
Solute: Same