1. Essential idea:
The evolution of multicellular organisms allowed cell specialization and cell replacement.

2. Nature of Science
Looking for trends and discrepancies—although most organisms conform to cell theory, there are exceptions. (3.1) Ethical implications of research—research involving stem cells is growing in importance and raises ethical issues. (4.5)

3. Assessment Statement Outline Cell theory

4. Cell Theory
KEY CONCEPT Cells are the basic unit of life.

5. All living things are made of cells.
Outline Cell Theory
All living things are made of cells.
Cells are the smallest unit of life.
Existing cells have come from other cells.

6. Outline Cell Theory
How did the below scientist contribute to Cell Theory???

7. Evidence for Cell Theory
Assessment State Discuss the evidence for Cell Theory

8. Evidence for Cell Theory
a. All living things are made of cells:

When living things are observed under the microscope they consistently appear to be composed of cells.

9. Evidence for Cell Theory
b. Cells are the smallest unit of life.
The cell is the smallest unit of organisation that can show all the characteristics of living processes, including:
Metabolism
Response
Sensitivity
Growth
Reproduction
Nutrition
DNA
Respire
Organelles often require the cooperation of other organelles for their successful function.

10. Evidence for Cell Theory
c. Cells come only from other cells.
Cells carry out a form of cell division to form new cells. This process of cell replication in eukaryotes is called Mitosis and in prokaryotes is called binary fission.
This aspect of cell theory suggests that all cells therefore have a common ancestor, the original ancestral cell form which all other cells have arisen by descent. (origin of cellular life).
This relationship of common ancestor suggest that all organisms are related.

11. Limitations of Cell Theory

12. Questioning Cell Theory.
Using atypical examples: Discuss problem in Cell Theory:
Striated Muscles Example
Giant Algae Example
Fungal Hyphae Example

13. Functions of Life
Assessment Statement State that unicellular organisms carry out all the function of life

14. Functions of Life
Organisms are able to carry out all the processes which are characteristic of living things such as:
a. metabolism which includes respiration the synthesis of ATP.
b. response to a change in the environment
c. homeostasis the maintenance and regulation of internal cell conditions.
d. growth which for a unicellular organism means an increase in cell size and volume.
e. reproduction which for the unicellular organism is largely asexual through cell division to form a clone.
f. nutrition which means either the synthesis of organic molecules or the absorption of organic matter.

15. Relative Sizes
Assessment Statements Compare relative sizes of molecules, cell membrane thickness, eukaryotes, viruses, bacteria and cells using the appropriate SI units

16. Relative Sizes
Relative sizes:
1. molecules (1nm). 
2. cell membrane thickness (10nm).
3. virus (100nm).
4. bacteria (1um).
5. organelles (less 10um).
6. cells (<100 um).
7. generally plant cells are larger than animal cells.

17. Relative Sizes
Molecules of Biological significance are around 1 nm in size where as the cell membrane is about ten times thicker at 10nm.
Where as a virus is ten times larger again at around 100nm.
where as a bacteria is ten times larger again at around 1 um.
where as a eukaryotic animal cell is is ten time larger again at around 10 um.
where as a eukaryotic plant cell is ten times larger again at around 100 um.

18. Magnification
Assessment Statement Calculate Linear Magnification of drawings and the actual size of specimens in images of know magnification

19. Units used in magnification calculations

20. Calculate Magnification of Specimen in Drawing=
Length of specimen in drawing/ photo (measured)
Actual length of specimen (estimated)
Calculate
Magnification

21. Explain how you would estimate the size of cell A.

22. Estimate the actual size of cell A.

23. Use actual length and measured length to calculate Linear magnification=
Length of specimen in drawing/ photo (measured)
Actual length of specimen (estimated)
Calculate
Magnification A
30 μm

24. Summary of Magnification Calculations

27. Estimate Size of Amoeba in mm & μm

28. Calculate Magnification
Actual length mm =
Measure length in photo mm= . =
Length of specimen in drawing/ photo (measured)
Actual length of specimen (estimated)
Calculate
Magnification

29. Estimate the size of the Daphnia in mm & μm
e mm
μm.

30. Calculate Magnification
Actual length mm =
Measure length in photo mm= . =
Length of specimen in drawing/ photo (measured)
Actual length of specimen (estimated)
Calculate
Magnification

31. Calculate Actual size
If a drawing of a cell has a magnification of 10X, and the length of the drawing is 20 mm. What is the actual length of the the cell?
Length of specimen in drawing/ photo (measured)
Actual length of specimen (estimated)
Calculate
Magnification =
Magnification
Actual length of specimen (estimated)

32. Calculating Actual Length
If the magnification of the drawing is 25Xwhat is the actual length of this drawing?

33. Calculating Actual Size

34. Calculating Actual Size

35. Calculating Actual Size

36. Assessment Statement:
Cell Size
Assessment Statement:
Explain the importance of the surface area to volume ratio as a factor of limiting cell size.

37. Surface area to volume ratio
Why are cells so small?
Surface area to volume ratio
As cell size increases, volume increase faster than surface area
Surface area to volume ratio decrease as cell increases
Thus less cytoplasm has contact with plasma membrane to exchange material with its environment.

38. Cells need a large surface area to volume ratio for three reasons:
Cell Size
Cells need a large surface area to volume ratio for three reasons:
Get rid of waste more quickly
Absorb materials from environment more quickly
Get rid of internal heat and absorb heat from the environment more quickly.

39. Cell Size Summary
The smaller the cell the more easily it can get rid of waste to, and absorb nutrients from, its environment.

40. Surface area increases while Total volume remains constant
Compare the Surface area of the solid box to the box made of a lot of small boxes 5 1 1
Total surface area
(height x width x
number of sides x
number of boxes) 6
150
750
Total volume
(height x width x length
X number of boxes) 1
125
125
Surface-to-volume
ratio
(surface area  volume) 6
1.2 6

41. Surface Area to Volume Ratio
The rate of exchange of substances therefore depends on the organism's surface area that is in contact with the surroundings. Reason: as organisms get bigger their volume and surface area both get bigger, but not by the same amount. The volume increases as the cube but the area of the surface only increases by the square.

42. Surface Area to Volume Ratio
Conclusions:
As the organism gets bigger its surface area : volume ratio decreases
This rule is a limiting factor for cell size.
As the cell gets bigger the ratio decreases
If the ratio decreases the rate of exchange decreases
Example: gas exchange of oxygen for respiration.
A cell which respires aerobically demands oxygen for the process.
Oxygen is obtained form the surrounding environment such as water or blood (depends on the cell).
Oxygen diffuses across the cell membrane.
More membrane more diffusion (Surface area= increases by the 2).
Bigger cell (Volume = increases by the 3).
However the ratio of surface area2 : volume 3 is decreasing
Therefore the volume of oxygen obtained for each unit of cell volume is actually decreasing
Cells must not get too big because they cannot obtain sufficient oxygen to satisfy the demands of the cell.

43. why cells are small (reasoning):
Size as a limiting Factors for cell because:
A big cell needs more oxygen than a little cell
Big cells need to have more oxygen diffusion across the cell membrane.
But the big cell has relatively small surface area compared to its volume i.e. the surface area: volume ratio is small.
What ever other benefits a cell might gain from being big, it cannot become larger than is limited by the rate of gas exchange.
This reasoning can be applied to nutrients and to waste, anything that is exchanged across the cell surface.
Try preparing a reason why size is a limiting factor for:
Obtaining nutrient (glucose)
Excretion of waste molecules ( urea, ammonia, carbon dioxide).

44. Emergent Properties
Assessment Statement: State that multicellular organisms show Emergent Properties

45. Emergent Properties
'Emergent properties arise from the interaction of the component parts; the whole is greater than the sum of the parts'.

46. Emergent Properties
Emergence is the occurrence of unexpected characteristics or properties in a complex system.
These properties emerge from the interaction of the ‘parts’ of the system.
Remember that biology insists on a population thinking so that we know the interacting ‘parts’ vary in themselves and therefore their ‘emerging’ properties can only be generalized.

47. Emergent Properties

48. Multicellular and Differentiation
Assessment Statement Explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others.

49. Multicellular and Differentiation
Rather than all cells carrying out all functions, tissues and organs specialize to particular functions.
These organs and systems are then integrated to give the whole organism (with its emergent properties).
Differentiation: Cells within a multi-cellular organism specialize their function.
Specialized cells have switched on particular genes (expressed) that correlate to these specialist functions.

50. Multicellular and Differentiation
These specific gene expressions produce particular shapes, functions and adaptations within a cell.
Therefore a muscle cell will express muscle genes but NOT those genes which are for nerve cells.

51. Multicellular and Differentiation
What is the benefit of differentiation and specialization of tissues rather than all tissues carrying out all functions?
In a multi cellular organism specialization is more efficient than the generalized plan when competing for a specific resource. Consider the role of water transport through the plant:
In higher plants we have specialization to for a tubular system called the xylem.
This is more efficient way of water transport than simply been passed by the mass movement of water from cell to cell.
In the xylem water can be moved very efficiently from underground to the canopy of the highest trees at very little cost to the plant.
If there is no specialized tissue for carrying water then the plant would rely on the movement of water by mass flow of diffusion which is very slow. The plant is therefore limited in size and therefore cannot compete with larger species.

52. Multicellular and Differentiation
Watch the below animation and then in your own words explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others

53. Multicellular and Differentiation

54. Multicellular and Differentiation

55. Stem Cells
State that stem cells retain the capacity to divide and have the ability to differentiate along different pathways

56. Ability to differentiate into specialized cells
What is a Stem Cell?
Unspecialized cells
Able to self-renew without differentiating for extended periods of time
Ability to differentiate into specialized cells
Embryonic and adult stem cells are derived from different sources.
Human blastocyst showing inner cell mass and trophectoderm
What Is a Stem Cell?
Stem cells are unspecialized cells that can self-renew (or “proliferate”) for extended periods of time without differentiating. They exhibit a stable, normal chromosome complement. Stem cells cannot perform any specialized functions but have the potential to give rise to cells with specialized functions (a process known as “differentiation”), such as pulsating heart muscle cells or defensive immune cells.
A fertilized egg is said to be “totipotent” because it has the potential to generate all cell types and tissues that make up an organism. Embryonic stem cells, derived from the inner cell mass of the blastocyst stage of development (pre-implantation, ~5-6 days old) have the potential to generate cell types and tissues from all three primary germ layers of the body (pluripotent). Adult stem cells (somatic stem cells) are found in tissues such as brain, bone marrow, skin, liver, skeletal muscle and peripheral blood vessels. It is suggested that some of these cells may be able to differentiate into multiple cell types (called “plasticity” or “trans-differentiation”). For example, brain stem cells may be able to generate blood and skeletal muscle cells. However, stem cells in adult tissues do not appear to have the same capacity or potential to differentiate as embryonic stem cells do. It may be that adult stem cells in many differentiated tissues are typically unipotent (capable of only one lineage).
References:
National Institutes of Health. (2002). Stem Cell Information. Retrieved , from
National Institutes of Health. (2001). Stem Cells: Scientific Progress and Future Directions. Retrieved August 5, 2004, from
Image Reference:
National Institutes of Health. (2001). Stem Cell Information. Retrieved , from
TIME 2001
Photo: Mr. J. Conaghan

57. What is an Embryonic Stem Cell?
Placenta cell
Fusion of nuclei
Stem cell
First cell division
Blastocyst (~5-6 days old): a “pre-embryo” ball of cells which has not implanted in the uterus.
Only cells between the nuclei fusion and blastocyst stages are considered true stem cells.
By the latter stages of development in the fetus, cells already have “decided” which tissues they are to become.
What is An Embryonic Stem Cell?
Embryogenesis is the process by which a single cell, formed from the union of the nucleus from a sperm and an egg, produces a complete organism. The fertilized egg is said to be totipotent, meaning that it has the potential to generate all the specialized cells and tissues of the body, as well as the tissues for its development in the uterus.
The DNA within the fertilized egg instructs the cell to divide (usually 24 – 36 hours after fertilization). The cell divides into two cells, and then each cell divides again, producing four cells. This process continues for about five to six days. At that point, the single cell has become a hollow ball of cells, called a blastocyst, that has not formed an attachment within the uterus. All mammals produce a hollow ball of cells during embryogenesis. The blastocyst is composed of two distinct cell types: 1) cells that will become the placenta; and 2) the inner cell mass. The inner mass of cells (in red) are stem cells. These cells are unique and described as pluripotent, since they retain the ability to read all information contained in the DNA within their nuclei and the capacity to generate cells from all three primary germ layers (mesoderm, ectoderm, and endoderm).
A very specific event occurs after about 5-6 days: the blastocyst changes very subtly and the cells in the inner cell mass lose their ability to read all of their DNA. In other words, cells are no longer pluripotent after this point in development.
References:
Gage, F. H. & I. M. Verma. (2003). Stem cells at the dawn of the 21st century. Proc Natl Acad Sci U S A 100 Suppl 1:
National Institutes of Health (2001). Stem Cells: Scientific Progress and Future Directions. Retrieved , from
National Institutes of Health. (2002). Stem Cell Information. Retrieved , from
Rhind S.M., Taylor, J.E., DeSousa, P.A., King, T. J., McGarry, M. and I. Wilmut. (2003). Human Cloning: Can it be made safe? Nature Reviews: Genetics 4:
Sylvester, K.G. & M.T. Longaker. (2004). Stem Cells. Arch Surg. 139:93-99.
University of Wisconsin-Madison. (2003). Stem Cell Basics. Retrieved , from
Image Reference:
Marx, J. (2004). Embryonic Stem Cells.
Stem cells are harvested from the inner cell mass.

58. Embryonic Stem Cells are Derived from Blastocysts
Placenta cell
Fusion of nuclei
Stem cell
First cell division
Blastocyst (~5-6 days old)
Undifferentiated stem cells are cultured (grown) in the laboratory.
Stem Cells Are Derived from Blastocysts
Scientists can remove the inner cell mass of a blastocyst by microsurgery or immunosurgery (use of antibodies). The harvested cells are transferred to a petri dish containing a specialized nutrient broth known as a culture medium. After days, when clumps of cells have formed, cells from the periphery are separated and plated in the same type of culture medium. Not all the cells of the inner cell mass will survive. Some will differentiate pre-maturely. Cells that do not differentiate and retain the ability to generate any cell type become stem cell lines. As the cells grow and crowd the dish, individual cells are removed and placed in a new dish to continue the cell culture. Cells that grow and do not differentiate for at least six months are called a stem cell line. These cells are described as being pluripotent, which means they are able to a give rise to cells of all three embryonic germ layers.
Since 1998, scientists have created about stem cell lines for research. These stem cell lines can be maintained for a very long time in the laboratory, and even frozen to be used at a later date.
References:
Gage, F. H. & I. M. Verma. (2003). "Stem cells at the dawn of the 21st century." Proc Natl Acad Sci U S A 100 Suppl 1:
National Institutes of Health. (2001). Stem Cells: Scientific Progress and Future Directions. Retrieved , from
National Institutes of Health. (2002). Stem Cell Information. Retrieved , from
Rhind S.M., Taylor, J.E., DeSousa, P.A., King, T. J., McGarry, M. and I. Wilmut. (2003). Human Cloning: Can it be made safe? Nature Reviews: Genetics 4:
Sylvester, K.G. & M.T. Longaker. (2004). Stem Cells. Arch Surg. 139:93-99.
University of Wisconsin-Madison. (2003). Stem Cell Basics. Retrieved , from
Image Reference:
Marx, J. (2004). Embryonic Stem Cells.
Stem cells are harvested from the inner cell mass.

59. Have two characteristics:
Adult Stem Cells
Have two characteristics:
They can make identical copies of themselves for the lifetime of the organism.
They can give rise to differentiated mature cells with specific morphologies (shapes and functions).
Adult stem cells are rare—and appear to help with homeostasis.
Stem cells have been found in the brain and spinal cord, dental pulp, blood vessels, skeletal muscle, the digestive system, the cornea and retina, and the liver and pancreas.
Adult Stem Cells
Recently, scientists have discovered cells in various parts of the human body (skeletal muscle, brain, liver, retina, etc.) that seem to exhibit many properties of blastocyst-derived stem cells. These cells are called “adult stem cells” or “somatic stem cells.” Adult stem cells are rare and dispersed throughout the body. Like all stem cells, they have the long-term ability to make identical copies of themselves and to produce differentiated mature cells.
While much is being learned, important questions remain about adult stem cells. Where are they found in the body and how many kinds exist? Can they be manipulated to grow, and do they normally exhibit the ability to generate cells of all tissue types? Can they access all of the DNA within their nuclei?
References:
National Institutes of Health. (2002). Stem Cell Information. Retrieved , from
Rhind S.M., Taylor, J.E., DeSousa, P.A., King, T. J., McGarry, M. & Wilmut. I. Human Cloning: Can it be made safe? Nature Reviews: Genetics 4:
Sylvester, K.G. & Longaker, M.T. (2004). Stem Cells. Arch Surg. 139:93-99.
University of Wisconsin-Madison. (2003). Stem Cell Basics. Retrieved , from

60. Stem Cells
A stem cell retains the capacity to divide and has the ability to differentiate along different pathways.
A stem cell is able to divide but has NOT yet expressed genes to specialize to a particular function. Under the right conditions stem cells can be induced to express particular genes and differentiate into a particular type of cell.

61. Embryonic Stem Cells Can Become Any Tissue in the Body
Blastocyst
Placenta cell
Stem cell
Cultured laboratory stem cells
Scientific manipulations entice stem cells to become specialized tissues (blood, muscle, neuron, etc.).
Embryonic Stem Cells Can Become Any Tissue In The Body
Stem cell cultures grown in the laboratory may be used to generate specialized, differentiated cells. The most common method to induce embryonic stem cells to differentiate is to introduce growth factors or change the chemical composition of the surface on which they grow. For example, if the growth surface medium is treated in such a way that the cells cannot adhere to it, the cells float and begin to interact with each other. This cell-to-cell interaction, when combined with the introduction of specific growth factors (in vitro), can induce cells to differentiate along a specific pathway.
In 1998, James Thompson at the University of Wisconsin-Madison was the first scientist to keep human embryonic stem cells alive in the laboratory. Before this, scientists could harvest the inner cell mass of the blastocyst, but were able to keep them alive only for a very short time.
References
National Institutes of Health. (2002). Stem Cell Information. Retrieved , from
Rhind S.M., Taylor, J.E., DeSousa, P.A., King, T. J., McGarry, M. & Wilmut. I. Human Cloning: Can it be made safe? Nature Reviews: Genetics 4:
Sylvester, K.G. & Longaker, M.T. (2004). Stem Cells. Arch Surg. 139:93-99.
University of Wisconsin-Madison. (2003). Stem Cell Basics. Retrieved , from
Image Reference:
Marx, J. (2004). Embryonic Stem Cells.
Muscle cells
Blood cells
Neuron (brain) cells

62. Stems Cells

63. Outline one use of stem cells (6 Points) Summarize.
Uses of Stem Cells
Assessment Statement
Outline one use of stem cells (6 Points)
Summarize.

64. Question 3
Outline one therapeutic use of stem cells (6 points).
Award [4 max] for any of the following general statements:
stem cells are cells that retain the capacity to divide and have the ability to differentiate along different paths into all types of cells / are pluripotent / totipotent;
stem cells are derived from blastocysts / human embryos, left over from IVF / placenta / umbilical cord / some adult tissues;
new techniques / technologies rely on replacing diseased / dysfunctional cells with healthy / functioning ones;
need to identify desired type of stem cell and grow in culture / special solutions / controlled conditions;
develop biochemical solution that will cause cells to differentiate into desired cell type;
develop means of implanting / integrating cells into patient’s own tissues so that they function with the body’s natural cells;
danger of rejection of cells therefore need to suppress immune system;
must make sure new cells do not become overgrown / develop into cancerous tumours;
Award [2 max] for a specific example ie: [1] for type of cells and [1] for proposed use:
eg retinal cells; replace dead cells in retina to cure presently incurable diseases such as glaucoma and macular degeneration;
eg graft new skin cells;
to treat serious burn victims;
eg nerve tissue;
help repair catastrophic spinal injuries / help victims of paralysisregain movement;

65. What Diseases Could Be Impacted by Stem Cell Research?
More than 100 million Americans suffer from diseases which might be alleviated by stem cell transplantation technologies.
Examples include cardiovascular disease, autoimmune disease, diabetes, osteoporosis, cancer, Alzheimer’s disease and Parkinson’s disease.
Stem cell treatment could potentially help patients with severe burns, spinal cord injuries, or birth defects.
Types of Research
Transplantation
Therapeutic delivery systems
Developmental studies
What Diseases Could Be Impacted by Stem Cell Research?
Research has shown that stem cell investigations may offer promising advances in medical treatment for a number of diseases and injuries. The use of stem cells to generate replacement tissues to treat neurological diseases, pancreatic disease, liver failure, chronic heart disease, cancer, and kidney failure is a major focus of scientists. The challenge is to take undifferentiated cells and direct their development into a purified specialized cell population. So far, only hematopoietic (blood producing) stem cells have been demonstrated safe for clinical application.
Current studies focus on the use of stem cells to generate transplantable and replacement tissues within the body. Scientists are working to apply stem cell research to the treatment of cancer by finding ways to deliver stem cell treatments that will either destroy or modify cancer cells. Stem cell research also is an important tool in our understanding of embryological development problems.
What lies ahead? According to the United States National Institutes of Health:
Predicting the future of stem cell applications is impossible, particularly given the very early stage of the science of stem cell biology. To date, it is impossible to predict which stem cells—those derived from the embryo, the fetus, or the adult—or which methods for manipulating the cells, will best meet the needs of basic research and clinical applications. The answers clearly lie in conducting more research.
References:
Gage, F. H. & I. M. Verma. (2003). "Stem cells at the dawn of the 21st century." Proc Natl Acad Sci U S A 100 Suppl 1:
National Institutes of Health. (2002). Stem Cell Information. Retrieved , from
National Institutes of Health. (2001). Stem Cells: Scientific Progress and Future Directions. Retrieved , from
Science (2000) 287:1423.

66. Uses of Stem Cells
Non-Hodgkins Lymphoma is a cancerous disease of the lymphatic system. 1. patient requires heavy does of radiation and or chemotherapy. This will destroy health blood tissue as well as the diseased tissue. 2. Blood is filtered for the presence of peripheral stem cells. Cells in the general circulation that can still differentiate into different types of blood cell otherwise known as stem cells. 3. Bone marrow can be removed before treatment. 4. Chemotherapy supplies toxic drugs to kill the cancerous cells. 5. Radiation can be used to kill the cancerous cells. In time however the cancerous cells adapt to this treatment so that radiation and chemotherapy are often used together. 6. Post radiation/ chemotherapy means that the patients health blood tissues is also destroyed by the treatment. 7. Healthy stem cells or marrow cells can be transplanted back to produce blood cells again

67. Animation of Stem Cells
Watch the Below Animation and then address the sunsequent assessment statements :
Assessment Statements:
State that stem cells retain the capacity to divide and have the ability to differentiate along different pathways
Outline one therapeutic use of stem cells.