1. The Plasma Membrane
The Gateway to the Cell

2. GPS
SB1. Students will analyze the nature of the relationships between structures and functions in living cells.
A. Explain the role of cell organelles for both prokaryotic and eukaryotic cells, including the cell membrane, in maintaining homeostasis and cell reproduction
D. Explain the impact of water on life processes (i.e., osmosis, diffusion)

3. Recall that
The process of maintaining balance in an organism’s internal environment is called---homeostasis!
Essential to survival
One of the primary structures for this is the…
PLASMA MEMBRANE!

4. Vocabulary Homeostasis Cell or plasma membrane Semipermeable
Phospholipid
Hypo-, Hyper-, Isotonic
Diffusion
Passive
Facilitated
Active transport

5. Phospholipids TAILS HEAD
Phospholipids have a hydrophilic end and a hydrophobic end.
Hydrophilic = water loving
Hydrophobic = water hating
TAILS
HEAD

6. The Hydrophilic ends rotate outward toward the water.
The Hydrophobic ends rotate inward toward each other.
This makes a double layer of phospholipids—phospholipid bilayer!

7. Structure of Cell Membrane
PHOSPHOLIPID 
PHOSPHOLIPID BILAYER
(CELL)
Cell Membrane 

8. Selective Permeability
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
Selective Permeability
The plasma membrane controls the movement of
substances into
and out of the cell.
Plasma Membrane
Controls the amount of a substance entering the cell
Controls the amount of a substance leaving the cell

9. Thin, flexible boundary between the cell and its environment
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
Plasma Membrane
Thin, flexible boundary between the cell and its environment
Allows nutrients into the cell
Allows waste to leave the cell

10. The plasma membrane is composed of the phospholipid bilayer.
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
The plasma membrane is composed of the phospholipid bilayer.
A phospholipid molecule is composed of a glycerol backbone, two fatty acid chains, and a phosphate group.

11. This membrane got moves!
Structure is not fixed (like a brick wall) but moves around – called a fluid mosaic

12. Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
Fluid Mosaic Model
The phospholipid bilayer allows other molecules to “float” in the membrane.
Other Components
Proteins
Cholesterol
Carbohydrates

13. Membrane Proteins
Marker Proteins – like nametags to identify the cell to other cells. Works with the immune system
Transport Proteins – Move materials into and out of the cell
Receptor Proteins – Allows the cell to interact with other cells.

14. Protein Channel

15. Ok, recap!!!
Selective permeability allows the membrane to control what enters and leaves the cell
Plasma membrane composed of 2 layers of phospholipid molecules
Cholesterol and transport proteins aid in function of membrane
Fluid mosaic model describes it

16. Fill in the blanks
The axillary border of the scapula is ________ to the vertebral border.
The hips are __________ to the shoulders.
The knee is ___________ to the ankle.
The cranium is __________ to the scalp.

17. How important is the receptor in a negative feedback system?

18. Sinoatrial (SA) node?

19. Name that quadrant. ?

20. Movement of Molecules Across the Cell Membrane
Passive Transport – requires no cellular energy
Active Transport – Requires cellular
energy

21. Types of Passive Transport
Diffusion –
Molecules move with a Concentration Gradient, from high concentration to low concentration.
Requires no energy
Molecules continue to move until an equilibrium is reached

22. 7.4 Cellular Transport Diffusion in a Cell
Cellular Structure and Function
7.4 Cellular Transport
Diffusion in a Cell

23. Osmosis
The Diffusion of Water Across a Selectively Permeable Membrane

24. Osmotic Pressure Gradients
In general, water moves toward the area with a higher solute concentration because it has a lower water concentration.

25. Hypertonic Solutions
Contain a higher concentration of solute outside of the cell than inside of the cell.
When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel.

26. Solute concentration is higher outside the cell.
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Hypertonic Solution
Solute concentration is higher outside the cell.
Water diffuses out of the cell.
Plant Cell
Blood Cell
13,000x

27. Hypotonic Solutions
Contain a low concentration of solute outside of the cell as compared to inside of the cell.
When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode.

28. Solute concentration is higher inside the cell.
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Hypotonic Solution
Solute concentration is higher inside the cell.
Water diffuses into the cell.
Plant Cell
Blood Cell
13,000x

29. Isotonic Solution
The concentration of solute inside of the cell is equal the concentration of solute outside of the cell. Therefore, water move equal into and out of the cell.

30. Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Isotonic Solution
Water and dissolved substances diffuse into and out of the cell at the same rate.
Plant Cell
Blood Cell
11,397x

31. Facilitated Diffusion
Diffusion with help!!
Uses Transport Proteins to move large molecule across the plasma membrane
Molecules move with the concentration gradient. Downhill !!

32. Carrier Proteins Channel Proteins 7.4 Cellular Transport Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Carrier Proteins
Channel Proteins

33. Active Transport
Move molecule against the concentration gradient. Uphill!!
Known as solute or ion pumps

34. Active Transport Using Carrier Proteins
7.4 Cellular Transport
Cellular Structure and Function
Active Transport
Movement of particles across the cell membrane using energy
Active Transport Using Carrier Proteins

35. 2 Special Types of Active Transport
Endocytosis - large molecules are engulfed by cell.
Phagocytosis – cell eats
Pinocytosis – cell drinks
Exocytosis – large molecules are removed from the cell.

36. Process by which the cell surrounds and takes particles into the cell
Cellular Structure and Function
7.4 Cellular Transport
Endocytosis
Process by which the cell surrounds and takes particles into the cell
Exocytosis
Secretion of material out of the plasma membrane