1. Outcomes A and G Chapters 3, 4, and parts of 7
Unit 2: Cell Biology
Outcomes A and G
Chapters 3, 4, and parts of 7
Prepared by: Wendy Vermillion Columbus State Community College
Reformatted for use at
G.P. Vanier by Ilene Yeomans

2. A. Cellular Level of Organization
1. Cells are the smallest unit of life
Exhibit all characteristics of life
Are highly organized
Many become specialized for complex functions
2. Cell theory
All living things are composed of cells
Cells are the functional and structural units of organisms
All cells are derived from previously existing cells
3. Discovery of cells
a) Antonie van Leeuwenhoek- invented the light microscope
b) Robert Hooke- first observed cells in cork (actually saw the cell walls of dead cells)
c) Schleiden and Schwann-proposed cell theory

3. Cellular level of organization, cont’d.
4. Cell size
Most cells are smaller than 1 mm in diameter
Surface area/volume ratio determines cell size:

4. Cell Size, cont’d. determining surface area to volume ratios
Cell Dimensions
Surface Area
Volume
SA/Vol
SA:Vol
1 cm x 1 cm
2 cm X 2 cm
6 cm x 6 cm
Let L be the length of one side
= L x L x 6
= L x L x L :1 :1 :1

5. Cell Size continued
As the cell size increases, the volume increases faster than the surface area does
Therefore small cells have a greater surface area to volume ratio than larger cells
Nutrients from the environment must cross the surface of the cell to enter
Cells must be small in order for the surface area to be adequate to supply nutrients
This is one reason why we are made up of lots of cells instead of just one big one

6. Cellular level of organization, cont’d.

7. B. Eukaryotic cells Eukaryotic cells have a membrane-bound nucleus
Cell Membrane (or Plasma Membrane)

8. Eukaryotic cells, cont’d.
Organelles
Subcellular structures which perform specific life functions for the cell
Many organelles are found in both animal and plant cells
Some are found exclusively in plants or animals
Plants
chloroplasts, large central vacuole, cell wall
Animals
centrioles

9. Animal cell anatomy
Fig. 3.2

10. Eukaryotic Cells cont’d
Nucleus
Contains the genetic material (DNA)
Nucleoplasm -semifluid within nucleus
Chromatin -threadlike DNA which has a grainy appearance
Nucleoli (Nucleolus) -dark regions of chromatin
These produce rRNA which makes up the two subunits of ribosomes when combined with protein
Nuclear membrane - double layered, surrounds nucleus and has large pores

11. The Nucleus and Nuclear Envelope
Fig 3.4

12. C. Animal Cell Organelles
1. Ribosomes-
Site of protein assembly (“Protein Synthesis”)
Composed of rRNA and protein subunits
Exist either as free ribosomes (in groups called polysomes) or bound to endoplasmic reticulum (ER)
Polysomes produce multiple copies of the same protein for use inside the cell
Proteins produced at the ER’s ribosomes are destined for export from the cell

13. 2. Rough endoplasmic reticulum (RER)
Organelles, cont’d.
2. Rough endoplasmic reticulum (RER)
Complex system of sacs and channels
Has attached ribosomes
Serves as site of assembly of proteins for export
Assembled proteins enter channels for processing
e.g. addition of sugar chains to form glycoproteins
Released in vesicles
3. Smooth endoplasmic reticulum (SER)
No ribosomes
Synthesizes lipid products such as phospholipids and steroids AND is used to detoxify
Product released in vesicles

14. The Endoplasmic Reticulum
Fig 3.5

15. 4. Golgi Apparatus (or Golgi Body)
Organelles, cont’d.
4. Golgi Apparatus (or Golgi Body)
Packaging and processing center for cell products
Receives the vesicles from ER
Vesicles fuse with Golgi and products are released inside
Further modification of proteins occurs
Products are packaged into secretory vesicles and released to travel to the cell membrane
Golgi also produces lysosomes
Easier to remember the functions with
MRS Golgi =
M (modify), R (repackage), S (sort)

16. The Endomembrane System
Smooth ER
Rough ER
Fig 3.6

17. 5. Lysosomes Contain hydrolytic enzymes (very powerful enzymes)
Organelles, cont’d.
5. Lysosomes
Contain hydrolytic enzymes (very powerful enzymes)
Three functions of lysosomes:
Intracellular Digestion
lysosome fuses with a vesicle and digests its contents
Autodigestion
lysosomes fuse with worn out organelles or cell components and digest them (e.g. mitochondria)
Autolysis
lysosomes sometimes called “suicide sacs” because they release their enzymes into the cell causing cell death

18. The Endomembrane System
Fig 3.6

19. 6. Mitochondria Site of aerobic cellular respiration
Organelles, cont’d.
6. Mitochondria
Site of aerobic cellular respiration
= production of ATP (energy)
Uses oxygen we breathe and food that we eat to produce energy for every action in and of our body
Up to 38 ATP
are made per glucose molecule
6 O2 + C6H12O6  6 CO2 + 6 H2O

20. Mitochondrion Structure
Fig. 3.9

21. 7. Peroxisomes Specialized vesicles Smaller than lysosomes
Organelles, cont’d….
7. Peroxisomes
Specialized vesicles
Smaller than lysosomes
Contain powerful oxidative enzymes
Use oxygen to strip H’s from certain molecules
Produce peroxide (H2O2), hence the name
Role is detoxification
Found in large numbers in liver cells

22. 8. Vaults Serve as cellular transport vehicles (we think)
Organelles, continued
8. Vaults
Serve as cellular transport vehicles (we think)
Discovered in the early 1990s (do not show up with normal staining techniques)
Shaped like octagonal barrels, hollow, 3X size of ribosomes
Intriguingly, vaults are the same size and shape as nuclear pores
Research supports vaults’ role in transport from the nucleus to the cytoplasm
Unknown cargo, BUT are the right size to accommodate the two ribosomal subunits!

23. D. Cytoskeleton The Cytoskeleton Maintains cell shape
Allows cells to move or allows organelles to move within cells
Made of protein
Components include microfilaments and microtubules:
Microfilaments are slender fibers that often occur in bundles
e.g. ACTIN which works to contract muscles
Microtubules protrude from the centrosome and form centrioles, cilia, and flagella

24. Eukaryotic cells, cont’d.
Centrioles see p60
Short tubules with 9+0 pattern of microtubule triplets
In animal cells, centrosome is composed of 2 centrioles
Believed to be involved in microtubule formation including mitotic spindle
Basal Bodies
Found at the bases of both cilia and flagella
Organize the microtubules in the cilium or flagellum
Have a 9+0 arrangement of microtubules.

25. Centrioles
Fig. 3.14

26. E. Cellular Movement Cilia and Flagella
Cilia are generally multiple and hair-like
Move mucus (phlegm) up the trachea
Move the egg (or zygote) along the oviduct
Flagella occur single or double and are whip-like
Propel the sperm
BOTH have a 9+2 pattern of microtubules

27. Structure of Cilia and Flagella
Fig. 3.15

28. The Cell Membrane

29. F. Cell (Plasma) Membrane
1. Membrane Structure
Fluid-Mosaic Membrane Model (FMMM)
Phospholipid bilayer
Hydrophilic heads face surfaces
Hydrophobic tails face inward
Proteins
Integral proteins- embedded
Peripheral proteins- surface
Glycoproteins and Glycolipids
Cell markers (antigens)
Cholesterol
Changes fluidity of the membrane

30. Fluid-Mosaic Model of Membrane Structure
Fig. 4.1

31. Functions of the Cell Membrane
Cell Membrane cont’d
Functions of the Cell Membrane
Functions as a barrier between the cell and its environment
Regulates what enters or exits the cell (Regulates transport of substances into and out of the cell)
Contains receptors that determine how a cell will respond to stimuli in the environment
Contains proteins that are important in immune responses
It is a very dynamic, fluid structure

32. membrane protein diversity
Fig 4.2

33. G. Permeability of Cell Membrane
Cell membrane is selectively permeable
Some substances pass through the membrane freely while others do not
Crossing depends on factors like:
size and shape of molecule,
molecule’s chemical nature (e.g. lipid soluble?)
temperature
number of passages (channel proteins, carrier proteins, etc.)
Rate depends on:
concentration gradient of substance
permeability of membrane to substance
surface area of membrane
molecular weight of substance
distance travelled (thickness of membrane)

34. H. Passive Movement Passive Mechanisms (of crossing the cell membrane)
= no cellular energy required
Kinetic energy drives passive mechanisms
Movement is always from high concentration to low concentration
( = DOWN a concentration gradient)

35. Diffusion For instance:
Passive mechanisms….
For instance:
Diffusion
The movement of substances from an area of high concentration to an area of low concentration
Drink crystals in water
Perfume in a room
The movement of lipid-soluble substances directly through the phospholipid bilayer from an area of high concentration to an area of low concentration
Gases (oxygen and carbon dioxide)
Alcohol

36. Process of Diffusion
Fig. 4.4

37. 2. Facilitated Transport
Passive mechanisms….
2. Facilitated Transport
The movement of small, lipid-insoluble substances such as simple sugars and amino acids across a cell membrane
Uses a carrier protein
Movement is down a concentration gradient
High
Low

38. Facilitated Transport
Fig. 4.8

39. Movement of Molecules Across Cell Membranes
Table 4.1

40. Passive Mechanisms Cont’d
3. Osmosis-
A special case of diffusion = movement of WATER from an area of low solute concentration to an area of high solute concentration.
The water moves to an area of high ‘saltiness’ in order to dilute the area
Water moves through protein-lined pores (“aquaporins”) in the cell membrane.
Osmotic pressure- force that causes water to move in a direction

41. Tonicity Isotonic solutions-no change
Hypotonic solutions-cause cells to swell and burst
Hypertonic solutions-cause cells to shrink, or crenate

42. Osmosis demonstration
Fig. 4.6

43. Osmosis in animal and plant cells
Fig 4.7

44. Permeability of plasma membrane, cont’d.
I. Active Mechanisms
= require ATP
Active Transport
Uses ATP
Requires a carrier protein
Transports molecules from an area of low concentration to an area of high concentration
= (UP or AGAINST a concentration gradient)
Example:
sodium/potassium pump in nerve cells
Iodine accumulation in the thyroid gland
Low
High

45. Active Transport
Fig. 4.9

46. The Sodium-Potassium Pump
Fig 4.10

47. Active Mechanisms, cont’d.
2. Exocytosis
Requires ATP
Vesicle used
Transports cell products and wastes (big stuff) out of the cell by vesicle formation
Vesicles fuse with plasma membrane
Products are released
Vesicle membrane becomes part of the plasma membrane

48. Exocytosis
Fig 4.11

49. Active Mechanisms, cont’d
3. Endocytosis
Requires ATP
Vesicle used
Transports substances (big stuff) into the cell by vesicle formation
membrane invaginates and surrounds a substance, then pinches off to form a vesicle

50. Pinocytosis-”cell drinking” material is liquid or small
Endocytosis, cont’d
Pinocytosis-”cell drinking”
material is liquid or small
Receptor-mediated endocytosis is a specific type of pinocytosis which occurs in response to receptor stimulation
b) Phagocytosis-”cell eating”
material taken in is large like bacteria or cell debris

51. Endocytosis
Fig 4.12

52. POINTS TO PONDER
1. The stomach has two different types of secretory cells. The chief cells secrete pepsinogen (the inactive form of the enzyme pepsin), while the parietal cells secrete hydrochloric acid. Both of these cell types have lots of mitochondria to make ATP. The chief cells use ATP to make pepsinogen. Parietal cells use ATP to actively transport H+ and Cl- from the blood into the cells. Only one of these cell types also has extensive RER and Golgi. Which one and why?

53. POINTS TO PONDER
2. One type of the affliction epidermolysis bullosa is caused by a genetic defect that results in production of abnormally weak keratin. Based on your knowledge of the role of keratin, what part of the body do you think would be affected by this condition?

54. POINTS TO PONDER
3. Colostrum, the first milk a mother produces, contains an abundance of antibodies (infection-fighting proteins). By what means would you suggest these Ab’s are transported across the cells of a newborn’s digestive tract into his or her bloodstream?

55. Clinical-1
Kevin J and his wife have been trying to have a baby for the past three years. On seeking the help of a fertility specialist, Kevin learned that he has a hereditary form of male sterility involving non-motile sperm. His condition can be traced to defects in the cytoskeletal components of the sperm’s flagella. Based on this finding, the physician suspected that Kevin also has a long history of recurrent respiratory tract disease. Kevin confirmed that he has had colds, bronchitis and influenza more frequently than his friends. Why would the physician suspect this?

56. Clinical-2
When William H was helping victims in an earthquake-ravaged region, he developed severe diarrhea. He was diagnosed as having cholera, a disease transmitted through unsanitary water supplies that is spread by fecal contamination. The toxin produced by the cholera bacteria leads to the opening of Cl- channels in the lining of the intestine. Cl- then floods into the intestine. How does this account for the diarrhea that is severe enough to kill many who have cholera?