Human Cells Differentiation and stem cells

Learning Intention: To learn about Human cell types Success Criteria: By the end of the lesson I should be able to State what is a stem cell is State that there are different types of stem cells Explain the difference between embryonic and adult stem cells State what somatic and germline cells are Discuss the purpose of stem cell research Describe some ways that stem cells have been successfully used in medicine Explain some of the issues in stem cell research Discuss some of the misconceptions that people have about stem cell research State how cancer cells are different from normal cells Describe how cancer cells are formed

Introduction The human body is made up of many specialised cells that perform specific functions. Specialised cells arise from the differentiation of unspecialised cells during embryological development.

What are stem cells? Stem cells are unspecialised cells that have the ability to reproduce and differentiate into a diverse range of specialised cells.

Types of stem cells Embryonic Adult

Stem cell development Animation

Embryonic stem cells Embryonic stem cells are derived from an embryo about 4–5 days old (called a bastocyst). These cells have the ability to differentiate into all of the cell types that make up an organism.

Adult (tissue) stem cells Adult or tissue stem cells are found in small numbers in the tissues and organs of adults and children, including the brain, bone marrow, skeletal muscle and skin. These cells give rise to 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. These cells replenish differentiated cells that need replaced in the tissues in which they are found.

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.

Somatic cells Somatic cells are the differentiated cells that form the different types of body tissue that exist. They divide by mitosis to form more somatic cells. They differentiate to form different body tissue types: Epithelial cells – cover body surfaces and line body cavities Connective cells – includes blood, bone and cartilage cells Muscle cells – form muscle Nerve cells – form nervous tissue

Germline cells Germline cells include the gametes and the cells that produce the gametes. A germline cell is one that eventually leads to the formation of sex cells (gametes). A germline cell, like a somatic cell, is diploid. Its nucleus contains 23 pairs of homologous chromosomes.

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

Mutations Mutations in Germline cells are passed to offspring Mutations in Somatic cells are not passed to offspring

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.

For example, stem cells could be turned into new bone cells and then injected into weak or broken bones. Skin cells could replace burnt skin, and brain cells could help people who have suffered brain damage. Or they could become nerve cells that could heal spinal cord injuries. 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.

Parkinson's is a very common disease starting with mild symptoms, a mask-like face, stiffness and tremors until sufferers eventually become immobile. It is caused by a slow deterioration of certain brain cells (neurons) and there's no cure. 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. Using stem cells to treat Parkinson's disease

Therapeutic stem cell cloning

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.

Cancer cells Cancer cells have many characteristics that make them different from normal 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)

HPV 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.

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?