Here is a draft help wanted ad for phospholipids in the plasma membrane: Wanted: Phospholipids for plasma membrane Job description: Form a protective bi-layer around the cell to regulate what comes in and out. Use hydrophilic heads and hydrophobic tails to create a selective barrier. Traits: Must have both hydrophilic and hydrophobic regions. Hydrophilic head to interact with water-based solutions outside and inside the cell. Hydrophobic tail to interact with other phospholipid tails in the membrane interior. Location: Embedded in the plasma membrane surrounding the cell, with heads facing the intracellular and extracellular environments.

1. Bell Work (page 8)
• How is a plasma membrane different than a
cell wall?

2. Notes: Plasma Membrane (page 9)

3. Notes: Plasma Membrane (page 9)
• Maintains the proper concentration of
materials inside a cell by controlling the
passage of materials in and out of the cell

4. Notes: Plasma Membrane (page 9)
• Maintains the proper concentration of
materials inside a cell by controlling the
passage of materials in and out of the cell
• Selectively permeable: allows some materials
to pass through while keeping others out

5. Notes: Plasma Membrane (page 9)
• Maintains the proper concentration of
materials inside a cell by controlling the
passage of materials in and out of the cell
• Selectively permeable: allows some materials
to pass through while keeping others out
• All cells have a plasma membrane

6. Notes: Plasma Membrane (page 9)
• Maintains the proper concentration of
materials inside a cell by controlling the
passage of materials in and out of the cell
• Selectively permeable: allows some materials
to pass through while keeping others out
• All cells have a plasma membrane
• Made of phospholipids plus
proteins, carbohydrates, and cholesterol

7. Phospholipids
• “Head” end hydrophilic (loves water)

8. Phospholipids
• “Head” end hydrophilic (loves water)
• “Tail” end hydrophobic (hates water)

9. Phospholipids
• “Head” end hydrophilic (loves water)
• “Tail” end hydrophobic (hates water)

10. Phospholipids
• “Head” end hydrophilic (loves water)
• “Tail” end hydrophobic (hates water)
• Form a bi-layer with hydrophobic tails in the
middle and hydrophilic heads pointed
outward

11. Proteins
• Can be attached to the surface or embedded
in the membrane

12. Proteins
• Can be attached to the surface or embedded
in the membrane
• Involved in transport through the membrane

13. Proteins
• Can be attached to the surface or embedded
in the membrane
• Involved in transport through the membrane
• Channel proteins form “tunnels” that allow
substances through the membrane

14. Proteins
• Can be attached to the surface or embedded
in the membrane
• Involved in transport through the membrane
• Channel proteins form “tunnels” that allow
substances through the membrane
• Carrier proteins bind to substances and carry
them through the membrane

15. Carbohydrates
• Attached to the surface of the cell

16. Carbohydrates
• Attached to the surface of the cell
• Help cells to identifycells

17. Cholesterol
• Embedded in membrane

18. Cholesterol
• Embedded in membrane
• Helps stabilize and strengthen the cell
membrane

19. Cholesterol
• Embedded in membrane
• Helps stabilize and strengthen the cell
membrane
• Important in cell metabolism

20. Cholesterol
• Embedded in membrane
• Helps stabilize and strengthen the cell
membrane
• Important in cell metabolism
• Hydroxyl (OH) group is oriented to the outside

21. Bell Work (page 8)
• Why do all cells need a cell membrane in
order to survive?
• Checking: Reading WS 9.1 (blue)

22. Help Wanted Ad (page 8)
• Write a help wanted ad for one of the
molecules in the plasma membrane
(phospholipids, proteins, carbohydrates, or
cholesterol)
• Include:
– A job description (what the molecule will be
doing)
– Traits the molecule must have (what should the
molecule look like? Should it be hydrophobic,
hydrophilic, or both?)
– Where in the cell will the molecule be working?