1. Higher human biology
Unit 1 – human cells

2. 1 Division and differentiation in human cells
Cellular differentiation is the process by which a cell develops more specialised functions by expressing the genes characteristic for that type of cell.
(a) Stem cells — embryonic and tissue (adult) stem cells.
Stem cells are relatively unspecialised cells that can continue to divide and can differentiate into specialised cells of one or more types. During embryological development the unspecialised cells of the early embryo differentiate into cells with specialised functions. Tissue (adult) stem cells replenish differentiated cells that need to be replaced and give rise to a more limited range of cell types.

4. Some questions to think about
What is a cell?
What varieties of cell exist?
What is a tissue? Give some examples.
What is an organ? Give some examples.
What is a system? Give some examples. 4

5. Differentiation also occurs in later developmental stages tissue repair etc in mature adults5 5

6. Bozeman biology

7. Specialised cells
The human body is made up of many specialised cells that have specific structural, functional and biochemical properties
Specialised cells arise from the differentiation of unspecialised cells during embryo development.
Specialised cells with similar functions are grouped into tissues. Similar tissues are grouped into organs and similar organs are grouped into systems.

8. Specialised cells
Differentiation short film

9. Why have specialised cells?
Division of Labour
Multicellular organisms have millions of cells
To ensure all process carried out – division of labour where cells become differentiated and specialised to carry out 1 specific function

10. Cell differentiation is under genetic control and involves cell signalling processes.
During differentiation, genes that express proteins important for the function of that cell remain ‘switched on’.
Once a cell becomes specialised, it stops dividing and only expresses the genes are characteristic for that type of cell.

11. Differentiation
During differentiation, certain genes that express proteins important for the function of a specific cell are ‘switched on’. This allows it to develop a more specialised structure to carry out a specific function.
Once a cell becomes differentiated it only expresses the genes that produce the proteins characteristic for that type of cell.

12. Stem cells Some questions to think about… What is a stem cell?
What are some different types of stem cells?
What is the purpose of stem cell research?
What are some ways that stem cells have been successfully used in medicine?
What are some of the issues in stem cell research?
What are some of the misconceptions that people have about stem cell research?

13. Stem cells film

15. What is a stem cell? Identical stem cells Stem cell SELF-RENEWAL
(copying)
Stem cell
Specialized cells
DIFFERENTIATION
(specializing)
What is a stem cell?
Note: The previous slide provides an alternative version of this diagram. The concept of a stem cell is very well explained in the short film, “A Stem Cell Story” at
What the diagram shows
Stem cells are different from other cells of the body because stem cells can both:
Self-renew: Make copies of themselves
AND
2. Differentiate: Make other types of cells – specialized cells of the body.
‘Specialized’ or ‘differentiated’ cells play particular roles in the body, e.g. blood cells, nerve cells, muscle cells. Specialized cells cannot divide to make copies of themselves. This makes stem cells very important. The body needs stem cells to replace specialized cells that die, are damaged or get used up.
Cell division – possible questions
1) 16+ year old students may remember learning about 2 kinds of cell division – mitosis and meiosis. They may have learnt that mitosis happens in wound healing or to replace short-lived cells, but probably won’t have discussed stem cells in this context. You might therefore need to explain that most specialized cells cannot undergo mitosis. There are a few exceptions (e.g. liver cells or T-cells) but in general specialized cells can no longer divide. Skin cells, red blood cells or gut lining cells cannot undergo mitosis. Stem cells do divide by mitosis and this makes them very important for replacing lost or damaged specialized cells.
Should mitosis be discussed, you may wish to note the following: In mitosis, the DNA in the daughter cells is identical to the DNA in the dividing cell. This is true for dividing stem cells, both in self-renewal and in differentiation. In differentiation, the daughter cells are more specialized than the original stem cell. So, the daughter cells behave differently even though they have the same DNA as the stem cell. This is because there are lots of other molecules inside and around the cells that can change the way the cells behave.
3) Scientists think that when human stem cells divide they probably make EITHER two stem cells, OR two more specialized cells. In fruit flies, stem cells can divide to make one stem cell and one more specialized cell in a single division. 15

16. Why self-renew AND differentiate?
1 stem cell
Why self-renew AND differentiate?
1) Self renewal is needed because if the stem cells didn’t copy themselves, you would quickly run out. It is important for the body to maintain a pool of stem cells to use throughout your life.
2) Differentiation is important because specialized cells are used up, damaged or die all the time during your life. Specialized cells cannot divide and make copies of themselves, but they need to be replaced for your body to carry on working. For example, your body needs 100,000 million new blood cells every day. Of course, differentiation is also important for making all the different kinds of cell in the body during development of an embryo from a single fertilized egg.
Possible questions or misconceptions
1) School students may have learnt simply that ‘cells undergo mitosis to make copies of themselves to heal wounds or replace blood cells’. You may need to explain that specialized cells like skin, red blood or gut cells cannot undergo mitosis, which is why you need stem cells. There are a few exceptions (e.g. liver cells or T-cells) but in general specialized cells can no longer divide. For adult audiences, this could be expanded to cover the idea that there are intermediate cells (progenitors) between stem cells and specialized cells that divide to allow a large number of new cells to be made (see slide 26 on renewing tissues)
2) Scientists think that stem cells in the human body don’t generally divide to produce one stem cell and one specialized cell at the same time. They probably divide to make EITHER two stem cells, OR two more specialized cells. In fruit flies, stem cells can divide to make one stem cell and one more specialized cell.
1 stem cell
4 specialized cells
Differentiation - replaces dead or damaged
cells throughout your life
Self renewal - maintains the stem cell pool 16

17. Stem cell development animation

18. What are stem cells?
Stem cells are unspecialised cells that have the ability to reproduce to make more stem cells or differentiate into specialised cells of one or more types.
Why relatively? It is either unspecialised or not 18 18

19. Stem cell jargon/definitions
Potency A measure of how many types of specialized cell a stem cell can make
Stem cell type
Description
Examples
Totipotent
Each cell can develop into a new individual
Cells from early (1-3 days) embryos (zygote)
Pluripotent
Cells can form any (over 200) cell types
Some cells of blastocyst (5 to 14 days)
Multipotent
Cells differentiated, but can form a number of other tissues
Fetal tissue, cord blood, and adult stem cells
Unipotent
????
Spermatogonial cells in testicles only make sperm
Stem cell jargon
Scientists use the words pluripotent and multipotent to help them describe stem cells. ALL stem cells can both self-renew and differentiate, BUT some stem cells can make more kinds of specialized cells than others. The terms on the slide are the key ones to remember. There are also stem cells that are:
TOTIPOTENT: can differentiate into all types of specialized cells in the body PLUS cells that are needed during development of the embryo only: placenta, yolk sac, umbilical cord.
UNIPOTENT: can only differentiate into one type of specialized cell. For example, spermatogonial stem cells (found in the testicles) are unipotent because they can only form sperm cells.
A useful place to look up other words and phrases to do with stem cells is the EuroStemCell online glossary: 19

20. Types of stem cells
Embryonic
Adult

21. Embryonic stem cells

22. Embryonic stem cells
Embryonic stem cells are derived from unspecialised cells found within an embryo.
They have the ability to differentiate into all cell types that make up an organism.

23. Where are stem cells found?
zygote stem cells
Totipotent can diffrerentiate into all cells and placenta/ umbilical cord etc.
tissue stem cells
fetus, baby and throughout life
embryonic stem cells
blastocyst - a very early embryo about cells
Where are stem cells found?
There are different types of stem cells:
Embryonic stem cells: found in the blastocyst, a very early stage embryo that has about 50 to 100 cells;
Tissue stem cells: found in the tissues of the body (in a fetus, baby, child or adult).
(Tissue stem cells are sometimes referred to as adult stem cells, even though they are found in the fetus and in babies, as well as in adults.) 23

24. Adult (tissue) stem cells

25. Do adult vs embryo stem cell card sort!

26. Adult (tissue) stem cells
Adult or tissue stem cells are found in various tissues of adults and children, including the brain, bone marrow, skeletal muscle and skin.
These cells replenish differentiated cells that need replaced through age or damage in the tissues in which they are found. They are able to differentiate into a much more limited range of cell types and will tend to develop into cell types that are closely related to the tissue in which they are found.
Eg adult stem cells in bone marrow will produce red blood cells, platelets, phagocytes and lymphocytes.

27. Other types of stem cells
Stem cells can also be taken from the umbilical cord of new babies.
Like adult stem cells, these cells can differentiate into a limited range of specialised cells.

28. Induced pluripotent stem cells - the exception to the rule!
Induced pluripotent stem (iPS) cells are adult cells that have had their nucleus genetically reprogrammed to an embryonic stem cell-like state.

32. (b) Somatic cells divide by mitosis to form more somatic cells
(b) Somatic cells divide by mitosis to form more somatic cells. These differentiate to form different body tissue types: epithelial, connective, muscle and nerve.

34. What do you think somatic cells are? Look at the pictures…..
B Lymphocyte
Smooth muscle
cartilage

35. Somatic cells neutrophil Ciliated epithelial cell Red blood cell
platelets

36. Somatic cells Cardiac muscle Squamous epithelial cells Nerve cells
T lymphocyte

37. Somatic cells
All body cells (except gametes and the cells which make them) are called somatic cells. They divide by mitosis and differentiate to form more cells of that tissue.
Mutations that occur in somatic cells aren’t passed onto offspring.
Please see comments in Teacher notes regarding protein expression 37 37

38. Do somatic cell passport activity

39. Tissues and organs
Body organs are formed from a variety of tissues made from somatic cells. E.g.
Epithelial cells which cover the body surface and line body cavities (E.g bladder, respiratory etc)
Connective tissue includes blood, bone and cartilage cells
Muscle cells form muscle tissue
Nerve cells form nervous tissue

40. Give an account, with examples, of the different body tissue types and their functions. (8 marks)
Body tissue cells derive from somatic stem cells …
by repeated mitosis.
Epithelial tissue - covers the organ surfaces.
Protection - skin / secretion - intestinal glands / absorption - villi.
Connective tissue - gives shape to organs and supports them.
Protection - skull bones / structural framework - ribs / storage of energy - adipose tissue / connecting body organs - blood / connecting epithelial to muscle tissue - cartilage (in tendons)
Muscle tissue - which causes locomotion or movement within organs.
Skeletal muscle - locomotion / smooth muscle - in arterioles control of access to capillary bed / cardiac muscle - contraction of the heart.
Nervous tissue - which transmits messages between the central nervous system and the rest of the body (and within the central nervous system).
Neurons - conduct impulses / glial cells - maintain a constant environment for neurons.

41. (c) Germline cells divide by mitosis to produce more germline cells or by meiosis to produce haploid gametes. Mutations in germline cells are passed to offspring. Mutations in somatic cells are not passed to offspring.

43. What do you think germline cells are?

44. Division of germline cells
Germline cells can divide by mitosis to produce more germline cells.
Germline cells can divide by meiosis to produce gametes.

45. Germline cells
Gametes and the cells that produce the gametes are called germline cells. They divide either by mitosis to produce more germline cells or by meiosis to produce gametes.
Mutations that occur in germline cells are passed onto offspring

46. Stage 1 – chromosomes copy themselves
Stage 4 – homologous pairs of chromosomes line up at equator
Stage 5- chromosomes pulled apart by spindle fibres
Stage 6 – 2 cells formed
Stage 8 – individual chromosomes line up at equator
Stage 9 – chromosomes pulled apart by spindle fibres
Stage 10 – gamete cells formed with half a chromosome complement

47. Give an account of cell differentiation under the following headings: stem cells somatic cells germline cells

49. (d) Research and therapeutic uses of stem cells by reference to the repair of damaged or diseased organs or tissues. Stem cells can also be used as model cells to study how diseases develop or for drug testing. The ethical issues of stem cell use and the regulation of their use.

51. Stem cell research

52. Therapeutic stem cells

53. TED talk Anthony Atala Growing new organs

54. Stem cell research
Stem cell research provides us with a wealth of information and can be studied in a variety of ways, including:
how cell processes such as growth, differentiation and gene regulation work
the study of diseases and their development
drug testing
therapeutic uses in the treatment of diseases such as leukaemia (bone marrow transplant), Hunter’s disease and heart disease
therapeutic uses in medicine, including skin grafts for burns and stem cell grafts for cornea repair.

55. For example, stem cells could be turned into new bone cells and then injected into weak or broken bones to speed up healing time.
A cool video showing heart cells beating in a dish…. 55 55

57. Windpipe Transplant

58. Or they could become nerve cells that could heal spinal cord injuries.

59. Skin cells could replace burnt skin, and brain cells could help people who have suffered brain damage.

60. Stem cells could be taken from someone with heart disease and be turned into heart cells, which can gather in a dish and throb! They could then be injected back into the patient to rebuild their heart tissue and combat heart disease.
Beating heart cells in a dish!

61. Symptoms: mask-like face, stiffness and tremors until sufferers eventually become immobile.
Replacing the affected brain cells seems more hopeful than finding better drugs. Many people think that stem cells could be grown into new brain cells that could help to treat or even cure Parkinson's.

62. Therapeutic stem cell cloning62

63. Stem cell uses Model cells to study how diseases develop Drug testing
Tissue replacement
e.g. skin grafting for burn patients
heart tissue for heart disease patients
brain nerve cells for Parkinson’s sufferers
blood for transfusion
nerve cells for spinal cord injuries

64. Do stem cell newspaper report activity

65. Corneal stem cell transplant
2 mins
2 mins
25 mins

66. Corneal stem cell therapy
Stem cells extracted from healthy eye, cultured (grown) and transplanted back into the damaged eye
Repairs cornea
Shorter waiting time than traditional donation
Reduced chance of rejection as patient’s own cells transplanted

67. Describe how stem cells have contributed to corneal transplants and skin grafts. 
stem cells isolated from the patient's healthy eye
new tissue can be cultured/grown
transplanted back into the damaged eye,
repair the damaged cornea.
Shorter waiting time than corneal donation
Skin grafts 
Stem cells isolated from healthy skin
New tissue grown / cultured
dehydration and infection are risks until graft done.
Produces skin cells much more quickly.
reduces the time patient at risk.

69. Presentation task
Using what you have learned already and adding further research, create a presentation that covers the following aspects of stem cells:
the biology of stem cells – what is a stem cell, types of stem cells
the potential of stem cells – details of one or two research projects involving stem cells that you have found particularly interesting, details of potential therapies
stem cell dilemmas – explore the moral and ethical issues surrounding stem cell research (personal points of view can be expressed if desired).
You will be assessed using all three of the above criteria as well as on the overall quality of your presentation. 69

70.
click interactive, 14-16, biology, then stem cell research

71. 71 Criteria 4 3 2 1 The biology of stem cells
Covers the topic in depth with details and examples. All key terms and words have been defined. Subject knowledge is excellent.
Includes essential knowledge about the topic. Subject knowledge is good.
Includes most information about the topic but there are some factual errors/omissions.
Content is minimal and there are several factual errors/omissions.
The potential of stem cells
More than one example of stem cell research has been covered in depth. More than one example of potential stem cell therapies has been explored.
At least one example of stem cell research has been covered in depth. Potential stem cell therapies have been covered.
An example(s) has been covered but is lacking in depth and detail of information.
Examples are minimal. Very few details given.
Stem cell dilemmas
The moral and ethical issues surrounding stem cell research have been explored in detail. More than one perspective has been given for many issues.
The moral and ethical issues surrounding stem cell research have been covered well. More than one perspective has been given for some issues.
Some moral and ethical issues have been mentioned but lack detail. Arguments detailed not balanced/only one perspective given.
Very little detail given in this area.
Quality of presentation
Interesting, well rehearsed, all members of group involved, word content of slide minimal, good eye contact with audience, smooth delivery.
Relatively interesting, fairly smooth delivery. Eye contact mainly good and most members of group involved at some stage.
Able to maintain interest of audience but delivery not smooth. Failed to make eye contact on some occasions. Some group members not involved.
Poor eye contact, not able to maintain interest of audience. Reading from slides, delivery not smooth. 71

72. The ethical issues of stem cell use
(15min) 72

73. Stem cell views

74. Watch the clip on stem cell research and answer the following questions
(7min)
What does Dr Snyder mean when he says stem cells are "flexible and plastic?"
In this video what evidence convinces you that stem cells can be used to cure spinal cord injury?
Dr Snyder points out that there are ethical concerns, and that there is no single answer that will please everyone. Who do you think should be the ones to decide where to obtain stem cells for medical research? 74

75. Do stem cell card sort for and against

76. Not in our back yard!
Should a business license be issued to ESC lifeworks Inc. by the city of Dundee?
Debate the issue- use the hand out to help organise the structure of the debate

79. Some useful Video Clips – Stem Cells and Ethics

80. Ethical issues surrounding stem cells
Practices using adult (tissue) stem cells remain fairly uncontroversial.
Many pro-life and religious groups argue that embryos have human rights, should not be destroyed and should not be created simply for scientific research.
Opposing arguments include the potential to discover cures for diseases for which there are currently none and improved treatment of a range of medical conditions.

81. Regulation of stem cell use
The laws surrounding embryonic stem cells and adult stem cells differ because while both have similar capacities in differentiation, their modes of derivation are not.
While embryonic stem cells are taken from embryos, adult cells can be taken from consenting adults.

82. Regulations surrounding the use of embryonic stem cells
The research must be licensed by the Human Fertilisation and Embryology Authority (HFEA).
Researchers must justify that the creation of an embryo is necessary and that the work could not be carried out in another way.
Embryos over the development stage of 14 days cannot be used as this is the stage at which there is some primitive development of the nervous system.

83. The use of stem cells in therapeutic treatments in the UK is currently restricted to adult stem cells.
Whether or not embryonic stem cells can be used in the future remains to be seen.

84. Cloning

85. Cloning
Human reproductive cloning is illegal in the UK. As a result of the Human Reproductive Cloning Act (2001) nobody in the UK is allowed to use cell nuclear transfer, or any other technique, to create a child.

86. Regulations surrounding stem cell use
Research must be licensed by the Human Fertilisation and Embryology Authority (HFEA).
Researchers must justify that the creation of an embryo is necessary and that the work could not be carried out in another way.
Embryos must be under 14 days old.
Human cloning is illegal in the UK

87. Compare the location and functions of embryonic and tissue (adult) stem cells. (7 marks)
Stem cells are undifferentiated cells capable of repeated division to both more stem cells and cells that will later differentiate to form specialised cells.
Embryonic stem cells (ESCs) are found in the inner cell mass of the blastocyst.
ESCs are capable of repeated division…
…to form more ESCs and other cell types.
ESCs are: capable of forming all the other cell types of the body / pluripotent
Tissue stem cells (TSCs) are found throughout the juvenile and adult body.
TSCs are capable of repeated division to form more TSCs and other cell types.
TSCs: can only form cells of the organ to which they belong / are multipotent.
e.g. bone marrow tissue cells can only give rise to bone marrow cells, red blood cells, platelets, phagocytes and lymphocytes.

88. (e) Cancer cells divide excessively to produce a mass of abnormal cells (a tumour) that do not respond to regulatory signals and may fail to attach to each other. If the cancer cells fail to attach to each other they can spread through the body to form secondary tumours.

90. Stuart brown – stooibrown@yahoo.com
Cancer.  I worked for ten years in the Dept of Surgical & Molecular Oncology at Ninewells so I can speak a bit about how cancer is researched and treated although there's not a lot I can say about pharmaceutical therapies - that stuff just went way over my head.  However, I can talk about the bowel cancer screening programme, for example and that might fit not just with this module but also with the public health bit later in the syllabus.  I also worked on x-ray ablation of breast cancer, cryogenic and thermal ablation of solid-organ cancers and a lot on colon cancer surgery.  Another thing I'm quite familiar with is the use of nanoparticles and microbubbles to pursue novel cancer therapies;

91. What is cancer?

92. TED talk

93. Reverse the odds app

94. Cancer cells
Cancer cells continue to reproduce to produce a mass of abnormal cells (a benign tumour).
They do not respond to normal regulatory signals that would instruct them to stop dividing when necessary.
They lose the molecules on their surface that would normally hold them in place and can therefore be detached from their neighbours, causing the cells to spread (malignant tumour).
Skin cancer cells (melanoma)

95. It is thought that 90–95% of cancers are caused by environmental and lifestyle factors such as obesity and tobacco.
It is estimated that 5–10% are due to genetics.

96. HPV – environmental factors
Certain strains of the human papilloma virus (HPV) have been shown to cause cervical cancer.
The routine immunisation programme in Scotland is for girls aged 12 and 13 (S2). There is also a one-off, three-year catch-up programme for older girls.

99. Watch melanoma film

100. UV sensitive yeast
UV sensitive strain of yeast: Baker’s yeast solution (saccharomyces cerevisiae) kept covered in foil.
Yeast glucose agar dish divided into 3 sections: sun with sunscreen / sun with no sunscreen / no sun
Use aseptic techniques
Expose to sunlight for 15 mins on bright day or longer on less bright day (or UV light)
Incubate 3-4 days at room temp 1-2 days at 30 degrees.
Count the number of colonies

101. Cancer
Cancer cells divide excessively to produce a mass of abnormal cells (called a tumour).
They do not respond to regulatory signals that would instruct them to stop dividing when necessary.
They may fail to attach to each other, called malignant tumours. This means they can spread throughout the body, forming secondary tumours.

102. Super Science: Nanotechnology
Imagine a tiny robot the size of a human cell, injected by the millions into your bloodstream on a search and destroy mission: to locate cancer cells, and kill them. Welcome to the scientific frontier of nanotechnology.

103. Your task
Produce an information leaflet designed to answer the questions of a patient recently diagnosed with cancer. Points to consider:
How are cancer cells different from other cells?
What is a tumour?
How will I know if my cancer has spread?
What is the difference between a malignant tumour and a benign tumour?
How will my cancer be treated?