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Selective Gene Expression Once a cell becomes differentiated it only expresses the genes that produce the proteins characteristic for that type of cell.

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Presentation on theme: "Selective Gene Expression Once a cell becomes differentiated it only expresses the genes that produce the proteins characteristic for that type of cell."— Presentation transcript:

1 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 cellEye lens cell (in embryo) Nerve cell Glycolysis enzyme genes (for respiration for energy) Crystallin gene (keep transparency & refractive index for lens clear) Insulin gene (needed for regulation Of glucose in blood) Haemoglobin gene (protein for oxygen transportation) Extension – can you think of other genes that would be needed to be expressed or other cells and gene?

2 Patterns of gene expression in specialized human cells Pancreas cell Eye lens cell (in embryo) Nerve cell Glycolysis enzyme genes Crystallin gene Insulin gene Hemoglobin gene Key: Active gene Inactive gene

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

5 Learning Outcomes Identify the different types of stem cells Understand the requirements for specialised cells and examine different tissues Define the term somatic cell Explore the ethical, financial and progress made in stem cell research

6 Stem cell jargon/definitions Potency A measure of how many types of specialized cell a stem cell can make Stem cell type DescriptionExamples 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

7 Stem cell jargon/definitions Potency A measure of how many types of specialized cell a stem cell can make Stem cell type DescriptionExamples 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 Can only differentiate into 1 type of specialized cell. Can only differentiate into 1 type of specialized cell. Spermatogonial cells in testicles only make sperm

8 Where are stem cells found? embryonic stem cells blastocyst - a very early embryo about cells tissue stem cells fetus, baby and throughout life zygote stem cells Totipotent can diffrerentiate into all cells and placenta/ umbilical cord etc.

9 What is a stem cell? Identical stem cells Stem cell SELF-RENEWAL (copying) Stem cell Specialized cells DIFFERENTIATION (specializing)

10 1 stem cell Self renewal - maintains the stem cell pool 4 specialized cells Differentiation - replaces dead or damaged cells throughout your life Why self-renew AND differentiate? 1 stem cell

11 stem cell What is a stem cell? stem cell SELF-RENEWAL (copying) REPRODUCE specialized cell e.g. muscle cell, nerve cell DIFFERENTIATION (specializing) Repeated mitosis and cell division while remaining undifferentiated

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13 Differentiation in somatic cells All differentiated cells (except reproductive cells) derived from stem cells are called somatic cells. Somatic cells form several different types of body tissues; Epithelial cells cover the body surface and line body cavities. Connective tissue includes blood, bone and cartilage cells, Muscle cells form muscle tissue Nerve cells form nervous tissue.

14 Epithial into goblet cells, ciliated cells, skin cells – all cells lining including blood vessels.

15 Tissue stem cells: Mesenchymal stem cells (MSCs) MSC bone marrow committed progenitors Bone (osteoblasts) Cartilage (chondrocytes) Fat (adipocytes) specialized cells

16 Tissue stem cells: Haematopoietic stem cells (HSCs) HSC committed progenitors neutrophil NK cell erythrocytes dendritic cell platelets megakaryocyte macrophage eosinophil basophil B cell T cell specialized cells bone marrow

17 Tissue stem cells: Neural stem cells (NSCs) NSC brain committed progenitors specialized cells Neurons Interneurons Oligodendrocytes Type 2 Astrocytes Type 1 Astrocytes

18 Tissue stem cells: Gut stem cells (GSCs) GSC Small intestine committed progenitors Paneth cells Columnar cells Goblet cells Endocrine cells specialized cells

19 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.

20 Issues with stem cells Therapeutic uses stem cells Research of stem cells

21 Issues with stem cells Therapeutic uses stem cells e.g. Repair damaged or diseased tissue Research of stem cells Information on how cell processes work (e.g.cell growth, differentiation and gene regulation) Model cells to study how diseases occur/ develop or for drug testing Skin grafts for burns Stem cell grafts for cornea repair Bone marrow transplants Ethics of embryo – when does life start? Expensive Unknown potential risk Reduces alternative research into cures/therapies

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