1. Chapter 7 A View of the Cell Pages 175 - 178
7.2 The Plasma Membrane
Chapter 7
A View of the Cell
Pages

2. Homeostasis – Maintaining a Balance
Cells must keep the proper concentration of nutrients and water and eliminate wastes.
The plasma membrane is selectively permeable – it will allow some things to pass through, while blocking other things.
A cell's contents would be the same as its surrounds, were it not for selective permeability.

3. Structure of the Plasma Membrane
Because cells have a watery environment both inside and outside, the polar ends of the phospholipids in the plasma membrane form double layers
The double layer of the plasma membrane is called a lipid bilayer

4. Structure of the Plasma Membrane
Lipid bilayer – two sheets of lipids (phospholipids).
Found around the cell, the nucleus, vacuoles, mitochondria, and chloroplasts.
Embedded with proteins and strengthened with cholesterol molecules.

5. What is a Phospholipid? A phospholipid is like a fat molecule but has
one less fatty acid group
a phosphate portion.

7. What’s a Phospholipid?
Polar (water-soluble) heads face out and the nonpolar fatty acids hang inside.

8. Hydrophobic / Hydrophillic
Hydrophobic = “afraid of water”
Non-polar side
This is the part that is like the fats – how does water act with oil?
Hydrophillic = “water loving”
Polar side
This is the side that is in contact with the watery environments.

9. Membrane Proteins
Determine what particles can pass through the membrane – like doors
Serve as enzymes (may speed reactions).
Act as markers that are recognized by chemicals and molecules from the inside and the outside of the cell (the immune system) – like a house number.

10. http://www. dartmouth. edu/~cbbc/courses/bio4/bio4-1997/02-theCell

11. outside the cell carbohydrate chains membrane protein interior of cell
cytoskeleton
cholesterol
carbohydrate
chains
membrane protein
This is my own drawing.
outside the cell
interior of cell

12. Carbohydrate sticking out
Diagram representing the cell membrane.
The above image is from
But I found it at An On-Line Biology Book:

17. Fluid Mosaic Model
Because the phospholipid molecules and some proteins are free to move, the plasma membrane is said to be a fluid mosaic.
The fluid mosaic model describes a structure with polar layers on the outside and nonpolar layer on the inside.

19. Fluid Mosaic Model
Which of the following pictures below most likely approximate the motion phospholipids make in a plasma membrane?

20. All of these things are true for plasma membranes:
Folded membranes increase surface area for efficiency.
Endoplasmic reticulum is made up of folded membranes.
Ribosomes are sometimes attached to folded membranes.

21. Carbohydrate chains
Membrane protein
Polar head of phospholipid
Non-polar tails of phospholipid
Cholesterol

22. What structure is analogous to a sewage system?
Membrane protein
Where are you least likely to find water?
Between the non-polar tails of the phospholipids
What would happen to the plasma membrane if part D is completely removed?
It would collapse on itself

23. Diseases of the plasma membrane
Decreased movement of molecules entering the cell might be a result of a disease that causes a thickened plasma membrane.
Cystic Fibrosis is a disease of the plasma membrane

24. Diseases of the plasma membrane
Cystic Fibrosis, incurable hereditary disorder that causes the body to secrete an abnormally thick, sticky mucus that clogs the pancreas and the lungs, leading to problems with breathing and digestion, infection, and ultimately, death.

25. Diseases of the plasma membrane
One of the most common fatal genetic disorders in the United States, cystic fibrosis occurs in about one in every 3,900 babies.

26. Diseases of the plasma membrane
Cystic fibrosis is caused by a defect in the gene responsible for making a protein that controls the flow of chloride ions into and out of certain cells through the membrane.