Bell Work (page 8)

• How is a plasma membrane different than a cell wall?

Notes: Plasma Membrane (page 9)

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

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

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

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

Phospholipids

• “Head” end hydrophilic (loves water)

Phospholipids

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

Phospholipids

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

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

Proteins

• Can be attached to the surface or embedded in the membrane

Proteins

• Can be attached to the surface or embedded in the membrane

• Involved in transport through the membrane

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

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

Carbohydrates

• Attached to the surface of the cell

Carbohydrates

• Attached to the surface of the cell• Help cells to identify cells

Cholesterol

• Embedded in membrane

Cholesterol

• Embedded in membrane• Helps stabilize and strengthen the cell

membrane

Cholesterol

• Embedded in membrane• Helps stabilize and strengthen the cell

membrane• Important in cell metabolism

Cholesterol

• Embedded in membrane• Helps stabilize and strengthen the cell

membrane• Important in cell metabolism• Hydroxyl (OH) group is oriented to the outside

Bell Work (page 8)

• Why do all cells need a cell membrane in order to survive?

• Checking: Reading WS 9.1 (blue)

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?