CfE Higher Biology: Unit 1 Key Area 4(a) Cellular Differentiation Stem Cells and Meristems 03/09/2018 CfE Higher Biology LR Unit 1: DNA and the Genome Cellular Differentiation We are learning to • Understand and explain the term differentiation. • Describe the role of plant meristems and how they generate new tissue during plant growth. Describe the role of animal stem cells. I can • Define the term differentiation • Describe what processes stem cells can carry out • Explain the purpose of stem cells Introduction Specialised cells arise from the differentiation of unspecialised cells during embryological development. Differentiation is when an unspecialised cell becomes specialised. Can you remember what has to happen to give each cell it’s particular phenotype? CfE Higher Biology 03/09/2018 Unit 1: DNA and the Genome Selective Gene Expression • Once a cell becomes differentiated it only expresses the genes that produce the proteins characteristic for that type of cell. • So which would be turned on? Pancreas cell Eye lens cell Nerve cell (in embryo) Crystallin gene Glycolysis enzyme genes (keep transparency & (for respiration refractive index for lens clear) for energy) Insulin gene Haemoglobin gene (needed for regulation (protein for oxygen Of glucose in blood) transportation) CfE Higher Biology 03/09/2018 Unit 1: DNA and the Genome Patterns of gene expression in specialised human cells Pancreas Eye lens cell Nerve cell cell (in embryo) Glycolysis enzyme genes Crystallin gene Insulin gene Hemoglobin gene Key: Active Inactive gene gene CfE Higher Biology 03/09/2018 Unit 1: DNA and the Genome What is a stem cell? • Master cell. • Undifferentiated (unspecialised cell type). • Found in all multicellular organisms. • Self-renewing and can differentiate. Stem Cells • Stem cells can be found in plant and animal cells CfE Higher Biology 03/09/2018 Unit 1: DNA and the Genome Plant Stem Cells Apical meristems Site of cell division Primary Growth Apical Meristems Apical meristems are the site of primary growth in a plant, and can be found at the root and shoot tips. There are 4 main areas within the meristem. 1 Zone of mitosis and cell division 2.These cells become elongated. 3.They become specialised (differentiated) to perform a particular function 4.They then form part of a permanent tissue which performs a particular role within the plant Zone of cell division Zone of cell elongation Zone of cell differentiation Zone of division Zone of elongation Zone of differentiation Perennial Plants Undifferentiated plant cells can be used in tissue culture Quick questions 1. What does the term differentiate mean? (1) 2. What is the term used to describe an undifferentiated cell? (1) 3. Where in a plant can stem cells be found? (2) 4. What do we call the area in plants where stem cells can be found? (1) 5. The plant stem cells used in tissue culture are described as being totipotent, what does this mean? (1) 6. In plant tissue culture, what is added to the callus to cause the cells of the callus to differentiate? (1) 7. Give two uses of plant tissue culture? (2) Animal stem cells Types of Stem Cells Animal stem cells are classified into two types: • Embryonic • Tissue (adult) They vary in their ability to differentiate. Embryonic stem cells Pluripotent: pluri = many potent = capacity • At blastocyst stage cells become pluripotent. • Have the capacity to become all cell types but not placenta. • Cells of most interest to research scientists. Tissue stem cells Multipotent • Can develop into cells that are closely related. • Limited number of several cell types. • Make all cell types from the tissue they come from. • Found in many parts of the body. • Can self-renew over a lifetime. Stem Cells in animals Watch the 15 minute video and make notes on the following: • What is the unique property of stem cells which makes them different from a specialised cell? • What does it mean when we say a cell has become ‘differentiated’? • Embryonic stem cells are described as pluripotent whereas adult stem cells are multipotent. Describe in your own words what these terms mean. • Why does adult tissue need stem cells? • Why are research scientists so interested in using stem cells? • We have discussed several types of stem cells. Which type do you think would be most useful to treat human disease? Give a reason for your answer. How much have you learnt? A Stem Cell Story: Quick Quiz This quiz is intended for use with the film A Stem Cell Story, available at www.eurostemcell.org/films 1. What is a stem cell? A A cell that can make copies of itself AND make more specialized types of cell B A cell that helps to fight against infections C A cell that is specialized D A cell that can produce all the cell types of the body 2. Where can scientists obtain stem cells? A Only from an embryo B Only from tissues in the body C Only from the brain D From an embryo or tissues in the body 3. Embryonic stem cells can differentiate into which types of cell? A Only brain stem cells and specialized brain cells B All types of specialized cells C Only cells that can produce insulin D Only cells that can produce artificial skin 4. Neural stem cells from the brain can differentiate into which types of cell? A Only specialized brain cells B Specialized brain cells and specialized skin cells C All types of specialized cells D Only specialized blood cells 5. In the treatment of burns, scientists can use stem cells to help them replace… A All parts of the patient’s skin B Hair follicles and sweat glands C The outermost layer of the skin D All parts of the skin except sweat glands 6. What are cells ‘fed’ when they are grown in a lab? A Antibodies B Proteins and sugars C Salts D Other cells Image: Wellcome Library, London 7. A blastocyst is… A A very early stage embryo B A type of stem cell C Part of the blood system D A type of brain cell Yorgos Nikas/Wellcome Images 8. When are blastocycsts created in a laboratory? A At weekends B When blood supplies are low C During fertility treatment D Whenever scientists are studying cells K. Hardy/Wellcome Images 9. What are the roles of stem cells in our bodies? A We are not sure what roles stem cells play in the body B They produce new specialized cells to replace cells that die or get used up C They fight against infections D They perform specialized roles in the body (e.g. produce insulin, transmit signals in the nervous system, …) Image: Wellcome Library, London 10. What are stem cell scientists investigating today? A When and how embryonic stem cells make decisions to produce more specialized cells B How stem cells work in the body C How stem cells might be used to treat disease D All of the above Image: Wellcome Library, London Cellular Differentiation I can • Define the term differentiation • Describe what processes stem cells can carry out • Explain the purpose of stem cells Starter 1. What is the difference between multipotent and pluripotent? 2. Which stem cells are multipotent and which are pluripotent? 3. What two processes can a stem cell carry out? CfE Higher Biology 03/09/2018 Unit 1: DNA and the Genome THERAPEUTIC STEM CELLS We are learning to • Investigate the uses of stem cells in research and medical treatments. I can • Describe how stem cells can be used in the treatment of burns and corneal repair. • Describe how stem cells can be used as model cells in drug testing. • Identify the ethical issues of using stem cells. What is stem cell therapy? • Stem cell therapy is a set of techniques that aim to replace cells damaged or destroyed by disease with healthy functioning ones. The techniques themselves are still relatively new but their applications and benefits are broad. Some of the diseases they can help include: • Cancer • Parkinson's disease • Diabetes • Various injuries (e.g. spinal cord) • Corneal repair Current treatments • There are a number of stem cell therapies that are currently being investigated or used to treat a range of diseases. These are: • Adult stem cell transplants using bone marrow stem cells • Adult stem cell transplants using peripheral stem cells • Stem cell transplants using umbilical cord blood • Therapeutic cloning Stem cell research in Glasgow! Model cells • https://www.eurostemcell.org/disease- modelling-cells • Stem cells may help us understand how a complex organism develops from a fertilised egg. • Stem cells, either carrying the disease gene or engineered to contain disease genes, offer a viable alternative. Scientists could use stem cells to model disease processes in the laboratory, and better understand what goes wrong. • New medications could be tested for safety on specialized cells generated in large numbers from stem cell lines – reducing the need for animal testing. CfE Higher Biology 03/09/2018 Unit 1: DNA and the Genome Homework research task • Read through the notes on the use of stem cells in corneal repair and answer the questions • Corneal repair I can • Describe how stem cells can be used in the treatment of burns and corneal repair. • Describe how stem cells can be used as model cells in drug testing. • Identify the ethical issues of using stem cells. Starter • Identify 3 different ways stem cells can be used in research CfE Higher Biology 03/09/2018 Unit 1: DNA and the Genome Ethical Issues We are learning to • Identify the ethical issues associated with stem cell use. I can • Debate the use of stem cells Ethics Ethics refers to the moral values and rules that ought to govern human conduct.