1. Cells
August 28th, 2007

2. Cell History Robert Hooke (1635-1703)
Viewed slices of cork under a crude compound microscope
He saw boxes which reminded him of cells that monks lived in
Hence the name “cell”

3. Cell History Anton van Leeuwenhoek (1632-1723)
Designed an early microscope
First to see living organisms in a drop of water

4. Cell History Robert Brown (1773-1858)
Used special stains and dye to view nucleus

5. Cell History Theodor Schwann, zoologist, (1810-1882)
Rudolph Virchow, physician ( )
Mathias Schleiden,
botanist ( )

6. Cell Theory
Schleiden, Schwann and Virchow each contributed to the cell theory ( ):
Cells are the basic unit of structure and function of all living things
All living things are composed of one or more cells
New cells are produced from existing cells

7. Cell Types Prokaryotic Eukaryotic
First appear in fossil record 3.5 BYA
No membrane bound organelles
No Nucleus
Bacteria
Eukaryotic
Evolved 1.5 BYA
Have membrane bound organelles
Have Nucleus
Protists, fungi, animals, plants

8. Cell Structures Cell Membrane (AKA: Plasma Membrane)
Selectively permeable
Regulates what goes in and out
Flexible
Provides protection and support
Made of a lipid bilayer

9. Phospholipids Fatty acid tails are non-polar Heads are polar
Tails don’t want to be near water because water is polar so they are inside the bilayer.

10. Cell Membrane Lipid Bilayer Outside of cell Inside (cytoplasm)
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains

11. Cellular Transportation
The cell membrane is selectively permeable and allows some particles come into the cell and keeps some of them out.

12. 2 Types of Transportation
Passive Transport
* The cell does not use any energy.
* Materials flow down the concentration gradient from High concentration to low concentration
Active Transport
* Requires that the cell use energy.
* Movement of solutes against a concentration gradient from Low concentration to High concentration.

13. The 3 most common types of Passive Transport:
1. Diffusion
2. Osmosis
3. Facilitated Diffusion

14. Diffusion
The overall direction of the movement is referred to as the Gradient.
In diffusion molecules usually move “down the concentration gradient”..... flow from high concentration to low concentration.
A state of “equilibrium” is reached where molecules are uniformly distributed but continue to move randomly.

15. Direction of Diffusion
Simple Diffusion
Molecules
Direction of Diffusion
High Concentration
Low Concentration
Selectively Permeable Membrane

16. Osmosis
The diffusion of WATER across a selectively permeable membrane is called OSMOSIS.
Osmotic environments are classified by the concentration of the solutes in the solution.

17. Osmotic environments are classified as:
1. Isotonic
2. Hypertonic
3. Hypotonic

18. Isotonic Environment
In an Isotonic solution, the concentration of solutes outside and inside the cell are equal.
Water is moving in and out at an equal rate.
95% Water
5% Solutes
95% Water
5% Solutes

19. Hypertonic Environment
Concentration of solutes is greater outside the cell than inside the cell.
Water will move outside the cell… the cell will shrink and die.
97% Water
3% solute
95% Water
5% solute

20. Hypotonic Environment
Concentration of solutes is greater inside the cell than outside the cell.
Water will move inside the cell… the cell will swell, or burst, and die.
95% Water
5% solute
97% Water
3% solute

21. Facilitated Diffusion
The diffusion of large particles through channel proteins in the plasma membrane.
Example: Glucose moves in and out of cells through Facilitated Diffusion.

22. Types of Active Transport are: (Phagocytosis & Pinocytosis)
Active Transport *Solutes flow against the concentration gradient. * The cell uses energy… usually ATP. *Requires Transport Proteins
Types of Active Transport are:
1. Exocytosis
2. Endocytosis
(Phagocytosis & Pinocytosis)

23. Exocytosis (exo = outside, Cyto = cell) Moving substances outside the cell
Process of vesicles fusing with the plasma membrane and releasing their content to the outside of the cell.

24. Endocytosis (endo = inside, cyto = cell)
The capture of substances
outside the cell when the plasma membrane merges to engulf it.

25. Phagocytosis (phago = to eat, cyto = cell)
Phagocytosis occurs when undissolved solids enter a cell.
The plasma membrane wraps around the solid material and engulfs it, forming a vesicle.
Phagocytic cells, such as white blood cells, attack and engulf bacteria in this manner.

26. Pinocytosis (pino = to drink, cyto = cell)
Pinocytosis occurs when dissolved materials enter a cell.
The plasma membrane folds inward to form a channel allowing the liquid to enter.
The plasma membrane closes off the channel, encircling the liquid inside a vesicle.

27. Cell Structures
The cytoplasm is a jelly-like substance that holds many other organelles such as:
Endoplasmic Reticulum – transports lipids and proteins
Ribosomes – produce proteins
Golgi Apparatus – packages and delivers proteins
Mitochondria – Transform energy into a chemical form that can be used by the cell.
Lysosomes – Help with cell digestion
Peroxisomes – House enzymes that speed up chemical reactions.

28. Cell Structures (cont.)
Microfilaments/Microtubules – form cytoskeleton to help with cell movement.
Centrosome – Contains centrioles that help during Mitosis.
Cilia/Flagella – Cellular extensions that aid in cell movement.
Vesicles – sacs that form to help particles come into and out of the cell.

29. Why are cells so small? Surface Area vs. Volume
As a cell grows larger, the volume increases faster than the SA
A bigger cell needs more nutrients, but has relatively less SA to take in those nutrients

30. Surface Area vs. Volume Cell Size 5 cm 10 cm Surface Area (l×w×6)
Volume (l×w×h)
125 cm3
1000 cm3
SA to Volume Ratio
150/125 = 6:5
600/1000 = 6:10

31. Cell Cycle Cells divide before growing too large
Before dividing, cells must prepare
Preparation = Interphase
G1 phase: Cell grows larger
S phase: Cell makes new DNA for daughter cell
G2 phase: Cell makes new organelles for daughter cell

32. Cell Cycle

33. Chromosomes Each chromosome is replicated during the S phase
Centromere
Sister Chromatids
Each chromosome is replicated during the S phase
A replicated chromosome has two identical sister chromatids connected by a centromere

34. Mitosis Four Stages: Prophase (pro- means first)
Metaphase (meta- means middle/after)
Anaphase (ana- means apart)
Telophase (telo- means far away/end)

35. Prophase Chromatin condenses into chromosomes
condensing
Chromatin condenses into chromosomes
Nuclear envelope and nucleolus disintegrate
Centrioles migrate to opposite ends of the cell
Spindle fibers form in foot ball shape across cell

36. Prophase

37. Metaphase Chromosomes line up in the middle (equator) of the cell
Spindle fibers attach to centromeres

38. Metaphase

39. Anaphase Sister chromatids separate
Spindle fibers shorten, pulling chromatids to opposite ends of cell
Animal cells begin to pinch in
Plant cells begin to form cell plate in the middle

40. Anaphase

41. Telophase
Nuclear membrane built from ER around each set of chromosomes
Nucleolus reforms in each nucleus
Chromosomes become mass of chromatin

42. Two cells dividing into four
Telophase
Two cells dividing into four

43. Cytokinesis
Final division of cytoplasm resulting in two daughter cells
Animals – Cell Membrane pinches together
Plants – Cell plate forms new Cell Membrane dividing into the daughter cells

44. Which phases can you see?
Anaphase
Prophase
Metaphase
Telophase
Interphase

45. Knowing when to divide Cyclins
Protein that regulates the cell cycle in eukaryotes
Internal regulators – tell the cell when to enter mitosis
External regulators – control the rate of the cell cycle

46. Cellular Response to Injury

47. Effect of Cyclins Cytoplasm is injected into a second cell in G2 phase
Cytoplasm is removed from cell in mitosis
Second cell enters mitosis

48. Cancer
Cancer results when cells do not respond to cell cycle regulators
Cells grow unregulated, forming a tumor
Tumor damages surrounding tissue

49. Leukemia – Blood cancer

50. Mammary (Breast) Cancer

51. Skin Cancer