1. Topic 1: CELL BIOLOGY
1.1 Introduction to Cells

2. The discovery of the cell is due to the development and advancements in technology
1590- Zaharias Janzen:
Invents the compound microscope
1665- Robert Hook:
Studies cork and coins “cells”
Antoine van Leeuwenhoek:
Discovers unicellular organisms

3. 1838- Mathias Schlieden:
All plants made of cells
1839- Theodor Schwann:
All animals were made of cells
1855- Rudolf Virchow:
All cells come from cells

4. The Cell

5. The Cell Theory
1. All living organisms are composed of cells, and the products of cells. (e.g. hair)
2. Cells are the smallest units of life.
3. Cells only come from pre-existing cells

6. * VIRUSES
Viruses are non-cellular structures consisting of DNA or RNA surrounded by a protein coat. Viruses are not considered as living cells.

7. Multicellular Organisms
Organisms comprised of more than one cell.
The cells in a multicellular organism work together to carry out the various functions of life.

8. Unicellular Organisms
Some organisms are unicellular meaning they are made of only a single cell.
(Examples: Amoeba, Chlorella, Euglena)
This single cell has to carry out all the 7 functions of life:

9. Amoeba Freshwater organism Chlorella
Single celled, photosynthetic green algae
Euglena
Fresh or salt water organism

10. FUNCTIONS OF LIFE
METABOLISM: chemical reactions inside the cell. ie: respiration
RESPONSE TO STIMULI: react to changes in environment (also known as sensitivity)
REPRODUCTION: production of offspring (sexual or asexual)

11. HOMEOSTASIS: keeping conditions inside the organism within tolerable limits
NUTRITION: obtaining food (for energy and growth)
GROWTH: increase in size
EXCRETION: removal of metabolic wastes

12. * Many unicellular organisms also have a method of movement, but some remain in a fixed position or drift with water or air currents.

13. Ex: the Amoeba Metabolism (cellular respiration, etc) Growth
Reproduction (asexual – mitosis)
Homeostasis- has contractile vacuoles to maintain osmotic equilibrium)
Response to stimuli- hypertonic and hypotonic solutions
Nutrition – via phagocytosis
Excretion – via diffusion and endocytosis

14. Ex: Paramecium A unicellular organism living in aquatic environments
Contractile vacoule- fills up with water and expels water to maintain tolerable cellular water levels
Cilia – for movement in response to stimuli
Food Vacoule – contains smaller consumed organisms
Nucleus – during asexual reproduction will divide into 2
Cytoplasm – where metabolic reactions take place
Cell Membrane – controls which chemicals come in or out of cell (incl O2)
- Excretion via diffusion

15. Ex: Chlamydomonas
Unicellular alga living in soil and fresh water habitats
Cytoplasm: site of metabolic reactions
Flagella: to move in response to light stimuli
Chloroplasts: for photosynthesis (nutrient production)
Cell Wall: Permeable;
Cell Membrane: Selectively Permeable to let in nutrients and wastes out
Contractile Vacoule – fills with water to keep cell at tolerable water levels
Nucleus: divides in asexual reproduction and fuses with another in sexual reproduction

16. Euglena
Chlorella

17. An electron microscope is used to study the internal structure of a cell (the organelles).
Because these structures are very small, special units are used to measure them:
Micrometre (μm) = 10-6 m
Nanometer (nm) = 10-9 m

18. Some typical sizes…. Eukaryotic cell: 10-100 μm (some larger)
Prokaryotic cell: 1-5 μm
Nucleus: μm
Bacteria: 1-4 μm
HIV virus: 100 nm
Cell membrane: 7.5 nm thick
Hydrogen atom: 0.1 nm

19. Calculating magnification using the scale bar
Diagrams and photographs can be shown larger or smaller than reality
A micrograph is a picture taken from a microscope. They are often magnified.
The magnification or a scale bar is given to indicate the real size of the object
A scale bar is a line that shows the actual size of the structures. (A 10 μm bar shows how big a 10 μm would appear)

20. Knowing the magnification, you can calculate the actual specimen size using the following formula:
size of image = specimen size x magnification
Specimen size = size of image
magnification
* Size of image is measured with your ruler

21. This is the same has the formula you learned in grade 10 optics:
M = hi ho

22. Magnification = Measured length of scale bar
scale value
* Make sure the units are the same

23. What is the real size of the amobea?

24. Surface Area : Volume
Surface area to volume ratio is important in the limitation of cell size.
The size of a cell is limited by its need to exchange materials with its environment
A large number of chemical reactions takes place in cytoplasm of the cell which means the cell has to be able to move materials in an out easily.

25. If a cell becomes too large:
its diffusion distance becomes too long to be efficient
Its surface area to volume ratio is too small to allow necessary exchange.

26. The rate with which a cell produces heat/waste and consumes resources is directly proportional to its volume. (The bigger the cell, the more wastes and resources)
Since the uptake of resources and the removal of heat/waste goes through the cell membrane, the rate of uptake/removal is proportional to its surface area. (The more surface area the more “entrances and exits”.

27. Surface Area : Volume # Blocks Surface Area Volume Reduced Ratio 1 2 34 6 8 16 32

28. Surface Area : Volume # Blocks Surface Area Volume Reduced Ratio 1 6
6:1 2 3 4 8 16 32

29. Surface Area : Volume # Blocks Surface Area Volume Reduced Ratio 1 6
6:1 2 10
5:1 3 4 8 16 32

30. Surface Area : Volume # Blocks Surface Area Volume Reduced Ratio 1 6
6:1 2 10
5:1 3 14 4 8 16 32

31. Surface Area : Volume # Blocks Surface Area Volume Reduced Ratio 1 6
6:1 2 10
5:1 3 14
4.7:1 4
18 or 16 8 16 32

32. Surface Area : Volume # Blocks Surface Area Volume Reduced Ratio 1 6
6:1 2 10
5:1 3 14
4.7:1 4
18 or 16
4.5:1 or 4:1 8 16 32

33. As a cell grows, its volume and surface area increase, however, the volume increases more rapidly than its surface area.
To deal with this, cells increase their surface area:
1) by dividing into 2 smaller cells
2) with protruding extensions
3) or by flattening the cell

34. Cell Division

36. Flat Cells

37. Emergent Properties Multicellular organisms show emergent properties.
This means that the organism can achieve more than the sum of what each cell could achieve individually, because of cell interaction.
Ex: anthill, human brain

38. Differentiation and Specialized Functions
In multicellular organisms such as humans, the DNA in every somatic cell (body cells, ie all cells excluding gametes) are identical.
ie, your stomach cells have the exact same DNA as your heart cells

39. Cells are specialized to perform one task, which is reflected in their structure or function.
Only a small portion of DNA in a cell is activated (or expressed) which makes that cell what it is.
Ex: In a stomach cell, on the genes that make it a stomach cell are expressed.

41. Genes that are not expressed by the cell, remain present in the nucleus but remain unaccessed or dormant.
Cells affect each other. The differentiation of a cell is determined by the cell’s position relative to others and by chemical gradients. (A heart cell will not develop when surrounded by liver cells)

42. Cell Specialization
By becoming specialized, the cells in a tissue carry out their role more efficiently than if they had many different roles.
Specialized cells develop their own ideal structure based on function

43. Red Blood Cells
Nerve Cells (neurons)
Smooth Muscle Cells
Sperm Cells

44. STEM CELLS Unspecialized cells
These cells can become almost any type of cell or tissue.
Embryo’s and the umbilical cord are sources of stem cells
Adults still have some stem cells in their bone marrow which can be used to treat diseases such as leukemia

45. Differences between stem cells and “normal cells”:
1. Stem cells are undifferentiated. (Most of their genes can still be expressed.) They have the potential to be any type of cell
2. Stem cells are self-sustaining. They can divide and replicate for long periods of time to create copious quantities of new cells. (Specialized cells will not replicate in isolation)

46. Therapeutics Use Stem Cells
Research is restricted and regulated
However, stems cells may be the key to curing many medical ailments
Ex: Stems cells can differentiate into specialized cells when given a certain chemical signal. Therefore, the potential to grow a new organ in vitro exists.

47. Therapeutic use of Stem Cells
CELL THERAPY: non-functioning cells are replaced with healthy, functioning cells
Ex: Bone Marrow Transplants for leukemia patients.
Ex: Skin grafts for burn victims
Ex: Can possibly cure diabetes, sickle cell anemia, Alzheimer's, and so much more

48. Ex: Stargardt’s Disease
Stargardt’s Macular Dystrophy
Genetic disorder that develops in children between ages 6 and 12.
Disease causes photoreceptive cells (light sensitive cells) in the retina (of the eye) to degenerate

50. Stargardt’s Disease As a result, vision becomes progressively worse
Vision loss can be so severe the individual may be considerer legally blind

51. Researchers have developed a way to make embryonic stem cells into retina cells
In Nov 2010, a woman with Stargardt’s was treated by injecting these retina cells derived from stem cells.
Her vision improved without any harmful side effects.

52. Ex: Leukemia Cancer is uncontrolled cell division
Leukemia is cancer of the white blood cells (wbc)
Normal wbc counts are between per mm3 of blood
Individuals have wbc counts between per mm3

53. Bone Marrow – where blood cells are made
Carry O2 to cells
Produce antibodies
Find invaders and initiate attack
Involved in blood clotting

54. Leukemia
Blood cells, including wbc, are made in bone marrow (soft tissue found in large bones such as the femur)
Bone marrow cells are adult stem cells. They are undifferentiated.
In an individual with leukemia, these bone marrow cells must be destroyed to cure the cancer.

55. Treating Leukemia
1) first, the patient must be put on chemotherapy to kill the cancerous bone marrow cells.
2) a bone marrow transplant is taken from a healthy donor. In this step, healthy bone marrow (adult stem cells) is extracted and injected into the patients body to multiply and produce red and white blood cells

56. Ethics of Stem Cells

57. Embryonic Stem Cells
SOURCE: by creating embryos in vitro (fertilizing an egg cell with a sperm cell).

58. Embryonic Stem Cells Pros Cons Almost unlimited growth potential
Can differentiate into any cell type
Less chance of genetic damage
Increased risk of becoming tumour cells
Removing these stem cells kill the embryo
when does a human life begin?
playing God?

59. Cord Blood Stem Cells SOURCE
Stem cells extracted from the blood from the umbilical cord of a new born baby.
Cells are frozen and stored for possible use later in life

60. Cord Blood Stem Cells PROS CONS Easily obtained and stored
Fully compatible with the tissues of the adult that growths from the baby (no rejection problems)
The umbilical cord is discarded whether or not stem cells taken from it
Limited capacity to differentiate into different cell types (can only naturally make blood cells though with research, possibly other types)
Limited quantities

61. Adult Stem Cells SOURCE
Stem cells obtained from some adult tissue such as bone marrow

62. Adult Stem Cells PROS CONS Less chance of developing tumours
Removal does not kill the adult in which they come from
Difficult to obtain (few sources, and buried deep in tissues)
Less growth potential than embryonic stem cells
Limited capacity to differentiate
Compatible to the adult which take from

63. Animations
Trachea