1. The Cell and Its Environment
Chapter 7
The Cell and Its Environment
The Cell Theory
All Organisms are made from one or more cells.
The cell is the basic unit of structure and function in organisms.
All cells are produced from other cells.

2. Plasma Membrane What is it? What is its purpose?
Boundary that separates the cell from its environment.
What is its purpose?
Controls which particles enter and leave the cell
Amino Acids
Glucose
Carbon Dioxide
This is Called “Selective Permeability”
The membrane only allows particles that are used by the cell or expelled to cross the membrane

3. The plasma membrane is made up of a lipid bilayer.
What is a lipid bilayer?
Composed of Phospholipids
- two layers of phospholipids form the plasma membrane
One end is water soluble – Phosphate group
The other end is nonsoluble. – Fatty acid end

4. Visual of the Lipid Bilayer
Phospholipid

5. Make up of the Plasma Membrane
What’s the basic structure of the Plasma Membrane?
Lipid Bilayer
Inside of the Lipid Bilayer are:
- Proteins – allow for transport of molecules
- allow for chemical reactions
- Carbohydrates – Recognition molecules
- Cholesterol – helps separate the fatty acid ends

6. Visual of the Plasma Membrane

7. Visual of the Plasma Membrane

8. Fluid Mosaic Model Why doesn’t it break apart?
What does it mean to be “fluid”?
What is mean to be “Mosaic”?
The components of the membrane are constantly moving
Why doesn’t it break apart?
Phospholipids are:
Hydrophilic – Polar ends – attracted to H20 (dissolves)
Hydrophobic – nonpolar end – not attracted to H20
(does not dissolve)

9. Visual of the Fluid Mosaic Model

10. Membrane Function Diffusion?
Random movement of particles from a greater concentration to a region of lesser concentration
Until “dynamic equilibrium”

11. Osmosis
What is it?
The diffusion of water into and out of cells across a selectively permeable membrane
Cells must maintain Osmotic Balance. Why?

12. More Osmosis

13. Even More Osmosis

14. cell cell H2O Lysed Turgid (normal) Isotonic solution
Fig. 7-13
H2O
Lysed
Turgid (normal)
Isotonic solution
Hypotonic solution
H2O
Normal
Flaccid
H2O
Shriveled
Plasmolyzed
Hypertonic solution
(a) Animal
cell
(b) Plant
cell

15. Facilitated Diffusion
The transport of particles across the plasma membrane with the use of transport proteins.
Channel Proteins (Pores)
- Allow transport of ions
- They are specific to the size and charge of the ions
Carrier Proteins – two types
- change shape to allow certain molecules to cross the plasma membrane
2. Gates – one particle attaches to the carrier protein changing its shape – allowing particles to freely pass across the membrane.

16. Visual of Facilitated Diffusion

17. More Facilitated Diffusion

18. Active Transport
Movement of particles from an area lesser concentration to an area of greater concentration
The transport proteins for active transport are called “pumps”
It costs the cell energy – that’s the difference between facilitated and active transport

19. Visual of Active Transport

20. Review Passive & Active Transport

21. Endocytosis and Exocytosis
Endocytosis – the plasma membrane surrounds and takes in substances from the environment
Exocytosis – removal of substances from the cell, opposite of Endocytosis

22. Endocytosis – Phagocytosis
Phagocytosis – solid chunks of material are taken into the cell

23. Endocytosis – Pinocytosis
Pinocytosis – liquid is taken into the cell

24. Endocytosis – Receptor-Aided
Protein Receptors identify specific particles for endocytosis

25. Endocytosis

26. Review A B - In your lab groups answer the following questions.
Define part “A” and “B” of the Molecule Below. A B
Explain how each part of the molecule behaves in H20?

27. Draw the arrangement of Molecules that make up the plasma membrane.
Review
Draw the arrangement of Molecules that make up the plasma membrane.
Explain the function of each molecule.
What makes the plasma membrane permeable to Water?
What does it mean to be selectively permeable?

28. Review What process causes water to enter a single cell organism?
What is this Process called?
What would happen to a single cell pond organism that was placed into pure water? Why?
What would happen to a single cell pond organism that was placed into salt water? Why?

29. Review
Diagram and explain the similarities and differences of the following:
Diffusion, Osmosis and Facilitated Diffusion.
Channel Proteins, Carrier Proteins and Gate Proteins.
Phagocytosis, Pinocytosis and Receptor-aided endocytosis.

30. Answer to #2 Channel Proteins (Pores) - Allow transport of ions
- They are specific to the size and charge of the ions
Carrier Proteins – two types
1. change shape to allow certain molecules to cross the plasma membrane
2. Gates – one particle attaches to he carrier protein changing its shape – allowing particles to freely pass across the membrane.

31. Review
Explain the difference between Active and Passive Transport.