Lesson 7A Specialized Cells, Stem Cells & Cellular Differentiation

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1 Lesson 7A Specialized Cells, Stem Cells & Cellular Differentiation

2 Learning Goals I can explain the concept of cell differentiation and cell specialization. I can explain how the cell structure relates to the functions of the specialized cells. I can explain the different types of stem cells. I can explain the importance of stem cell research and the ethical issues related to stem cell applications.

3 Specialized Cells Specialized cells have special shapes and structures that allow them to do specific functions (jobs)

4 How do cells become specialized? Cell differentiation: A cell becomes specialized to perform a specific job Is directed by the genetic information (in DNA) inside the cell Occurs in during early development of living organisms

5 Cell Differentiation

6 What is cell specialization? Cell specialization: Cells change from similar cells into cells that have specific functions within a multi-cellular organism E.g. A stem cell becomes a red blood cell that carries oxygen. What is the difference between cell specialization and cell differentiation? Cell specialization refers to the functions that certain cells have, such as red blood cells are specialized to carry oxygen. Cell differentiation is the process that a cell undergoes to get that specialization. We would say stem cells undergo cell differentiation to become red blood cells.

7 What is a specialized cell? A specialized cell: A cell that comes from a non-specialized cell (stem cell) look different from each other: smooth surface (red blood cells); long and thin with many branches (nerve cells)

8 A Specialized Cell: A cell that is different internally (inside cell) o muscle cells that use a lot of energy have more mitochondria o cells in intestine that produce mucus have more Golgi bodies o fat cells that store fat molecules have a large vacuole

9 A Specialized Cell: specific job carry out a o bone cells store calcium and build new bone o skeletal muscle cells contract to allow movement o fat cells store energy in the form of fat o nerve cells conduct electrical signals or coordinate activities o hair cells in the inner ear detect sound vibrations o red blood cells deliver oxygen and remove carbon dioxide o skin cells cover the body and reduce water loss

10 Where do the specialized cells come from?? Stem cell

11 What are Stem Cells? Stem Cells: Non-specialized cells that can produce various specialized cells

12 Human Embryonic Stem Cells Coloured scanning electron micrograph of human embryonic stem cells (Image: Miodrag Stojkovic/Science Photo Library)

13 What are Stem Cells? Can divide to produce copies of themselves through mitosis and cytokinesis Daughter cells can develop into different types of cells based on which genes are switched on

14 What are Stem Cells? Occurred in groups that differentiate into different tissues layers (epithelial, muscle, and nerve tissues) Can be found in various parts of the human body at every stage of development from embryo to adult Stomach stem cells labelled with green fluorescent protein

15 3 Types of Human Stem Cells Within 24 hrs Embryonic Stem Cells Within 4 5 days 1. Totipotent Stem Cells 2. Pluripotent Stem Cells Form any type of tissue Form many types of tissue After that 3. Adult Stem Cells Form specific types of tissue

16 3 Types of Stem Cells: Embryonic Stem Cells Found in very young embryos (< 1 week old) 2 Types of Embryonic Stem Cells: 1) Totipotent stem cells (early embryo within 24 hours) any kind Can become of cell 2) Pluripotent stem cells (embryo 4 to 5 days) many kinds Can become of cells, but not all types of cells

17 3 Types of Stem Cells: 2. Adult Stem Cells (Tissue stem cells) Found in the late development of the fetus or after birth Exist within specialized tissue or organ Only able to differentiate into certain type of cells Purpose: to maintain and repair the tissue in which they are found Adult stem cells in bone marrow

18 Adult Stem Cells (Tissue stem cells) can produce all of the cell types associated with the tissues from which they originate E.g. In heart produce cardiac muscle cells maintain and repair the body s tissues in which they are found.

19 Why are Stem Cells Useful? repair To and damaged human tissue treat replace cure To and disease and injuries

20 How might Stem Cells be used to develop treatments for diseases? Natural processes cannot replace most body s specialized cells if they are seriously damaged or diseased. Transplantation of healthy organs from donors has posed high risks Treat patients by transplanting specialized cells that are grown from stem cells in the lab.

21 Limb Amputations Disorders in Brain Potential Uses of Stem Cells Spinal Cord Injuries Heart Disease Burns Diabetes

22 The Medical Potential of Stem Cells: Adult Stem Cell Transplantation Bone marrow has adult stem cells that can differentiate into blood cells bone marrow transplants are often use to treat cancers that affect blood cells Bone marrow transplant: A procedure to replace damaged or destroyed bone marrow with healthy bone marrow stem cells; to replace replenish bone marrow that has been destroyed by drug or radiation therapy for cancer (leukemia).

23 stem cells treat diseases like cancer

24 The Medical Potential of Stem Cells: Adult Stem Cell Transplantation Umbilical cord blood has a high concentration of the adult stem cells treat childhood leukemia (cancer in bone marrow)

25 Issue with Embryonic Stem Cells: Where do the embryonic stem cells come from? 1. From human embryo left over from fertility treatments 2. From cloned human embryos developed in the lab

26 Human Embryos from In Vitro Fertilization (outside the body)

27 Issue with Embryonic Stem Cells The use of stem cells from human embryos may not be acceptable, so adult stem cells offer an alternative that has less ethical and moral complications.

28 Ethical Issues in Stem Cell Research Ethical issues: Consider the potential moral outcomes of stem cell technologies The controversy centered on the moral implications of destroying human embryos. Do embryonic stem cells represent a human life? When does life begin at fertilization, in the womb, or at birth? Is a human embryo the same as a human child? Does a human embryo have any rights? Might the killing of a single embryo be justified if it provides a cure for a countless number of patients? Should frozen embryos created through in vitro fertilization be used to create stem cells? Why or why not?

29 Legal Issues in Stem Cell Research Legal issues: Require researchers and the public to help policymakers decide whether and how stem cell technologies should be regulated by the government Should there be laws to regulate stem cell research? If so, what would they look like? For example, how would you regulate research using different types of stem cells, such as embryonic, fetal or adult stem cells? What about embryonic stem cells created using cloning technologies?

30 Social Issues in Stem Cell Research Social issues: The impact of stem cell technologies on society as a whole Will the medical benefits of stem cell research be available to all people? With the high costs of treatment and research will there be equality of access?