1. Chapter 3
Cells

2. The Cell Theory States:
Cells are the building blocks of all plants and animals
Cells are produced by the division of preexisting cells
Cells are the smallest units that perform all vital physiological functions
Each cell maintains homeostasis at the cellular level
Homeostasis at higher levels reflects combined, coordinated action of many cells

3. Figure 3.2 The Anatomy of a Representative Model Cell

4. Cell membrane functions include:
Physical isolation
Regulation of exchange with the environment
Sensitivity to the environment
Structural support

5. Figure 3.3 The Cell Membrane
The cell membrane is a phospholipid bilayer with proteins, lipids and carbohydrates.
Figure 3.3

6. Membrane Lipids:
Phospholipids: composed of glycerol and fatty acid tails linked by a phosphate group.
Acts as a selective physical barrier between cell and extracellular environment
Cholesterol and other lipids are also part of the membrane structure.

7. Membrane Proteins Include:
Anchoring proteins: attach to other structures to stabilize cell position
Recognition proteins: Identifies cell as “self”, nonself, normal, or abnormal
Receptor proteins: trigger changes in cell activity based materials in extracellualr environment that bind to them
Carrier proteins: bind and transport materials across cell membrane
Channel proteins: pores in cell membrane which allows solutes to diffuse in and out of cell
Enzymes: catalyze reactions in and out of cell.

8. Cell Membrane Proteins

9. Diffusion
Movement of a substance from an area of high concentration to low
Continues until concentration gradient is eliminated

10. Figure 3.4 Diffusion

11. Figure 3.5 Diffusion across the Cell Membrane

12. Osmosis
Diffusion of water across a semipermeable membrane in response to solute differences
Osmosis occurs across a selectively permeable membrane that is permeable to water but NOT freely permeable to solutes
In osmosis, water flows across a membrane toward the solution that has the HIGHER concentration of SOLUTES because that is where the concentration of WATER molecules is LOWER

13. Osmotic Pressure
OP = the force of water into a solution as a result of different solute concentrations.
Isotonic = no net gain or loss of water
Hypotonic = net gain of water into cell
Hemolysis (swelling or bursting of cell)
Hypertonic = net water flow out of cell
Crenation (shrinking of cell)

14. Figure 3.7 Osmotic flow across a cell membrane (RBC)

15. Transport Mechanisms Carrier mediated transport
Proteins bind and transport specific ions or organic molecules and transport them across the cell membrane
Cotransport: 2 substances move together
Counter-transport: 2 substances move in opposite directions
Passive Transport: no ATP required
Active Transport: ATP dependent

16. Carrier Mediated Transport
Facilitated diffusion (passive)
Compounds to be transported bind to a receptor site on a carrier protein
Not totally dependent on concentration of solutes
Active transport (active)
Consumes ATP
Independent of concentration gradients
Types of active transport include
Ion pumps
Exchange pumps

17. Facilitated Diffusion
Figure 3.8

18. The Sodium Potassium Exchange Pump
Figure 3.9

19. Vesicular transport
Material moves into or out of cells in membranous sacs
Endocytosis is movement of materials into the cell
Receptor-mediated endocytosis (coated vesicles)
Pinocytosis: cell drinking
Phagocytosis: cell eating (pseudopodia)
Exocytosis is ejection of materials from the cell
Hormones
Mucus
Waste products

20. Figure 3.10 Receptor-Mediated Endocytosis

21. Figure 3.11 Pinocytosis and Phagocytosis

22. Cell Division Cell division is the reproduction of cells
Apoptosis is the genetically controlled death of cells
Mitosis is the nuclear division of somatic cells
Meiosis produces sex cells

23. Interphase
Most somatic cells spend the majority of their lives in this phase
Interphase includes G1 S G2

24. Mitosis, or nuclear division, has four phases
Prophase
Metaphase
Anaphase
Telophase
During cytokinesis, the cytoplasm divides and cell division ends

25. The Cell Life Cycle

26. Interphase, Mitosis, and Cytokinesis

27. Interphase, Mitosis, and Cytokinesis

28. Mitotic rate and cancer
Generally, the longer the life expectancy of the cell, the slower the mitotic rate
Stem cells undergo frequent mitoses
Growth factors can stimulate cell division
Abnormal cell division produces tumors (neoplasms)
Benign
Malignant (invasive, and cancerous)
Spread via metastasis
Oncogenes

29. Cell Differentiation Process of specialization
Results from inactivation of particular genes
Produces populations of cells with limited capabilities
Differentiated cells form tissues