Stem Cells Goal Differentiation of cells in multicellular organisms - Cells respond to their environment by producing proteins -Advantages and disadvantages of production of proteins at the incorrect times

What are Stem Cells? Stem cells are undifferentiated cells that have the ability to produce more stem cells or produce specialized cells Every cell “STEMS” from stem cells! Cells that do not have a purpose.. yet…

Where are they found? Embryonic stem cells are found in the mass of cells that form an embryo (fertilized egg) – Umbilical cord blood has blood stem cells Adults have stem cells in various tissues – Bone marrow contains stem cells that make bone, cartilage, fat, and blood cells – The extent of adult stem cells is still being investigated Embryonic stem cells have more capabilities than adult stem cells

Stem cells in lab Embryonic stem cells can be “made” in a lab These cells can be altered by scientists to determine what type of cell it will become – Ex: cell can be “told” to become a muscle cell

Somatic Nuclear Transfer A process called Somatic Nuclear Transfer can create embryonic stem cells Process: – Nucleus is removed from an egg cell – The de-nucleated egg cell and a somatic cell are fused – It divides to form an embryo = stem cells – Can also be implanted in a uterus to make a cloned animal. Ex: Dolly the Sheep

 For Stem Cell Research For Cloning

Stem Cell Applications Cells can be used to replace damaged cells: a.Cardiac = heart attacks b.Liver = Hepititis c.Nerve = paralysis, brain damage or diseases d.Insulin cells in pancreas = diabetes e.Skin = burn victims

Bone Marrow Transplants

Cells from eye

stem cell research Embryos are formed in labs that help couples get pregnant. An egg is placed in a dish with sperm to be fertilized. The fertilized zygote is then implanted into a woman’s uterus. (In Vitro Fertilization) Sperm Eggs Fertilized – become a ball of cells

Stem cell research Many eggs are fertilized at a time and are not used to form a baby – if not used, they are discarded… Misconception: embryos are not aborted for stem cell research – they are donated So, the embryo used in research is 4-5 days old and contains about 150 cells

Cell Specialization Goal 2.02

Cell Specialization Cells are specialized – Shapes help determine function All cells begin as stem cells and then become a specialized cell

Examples of Specialized Cells Red Blood Cell Oval in shape, Flexible, Contains Hemoglobin in the center Function is to carry oxygen throughout body

Examples of Specialized Cells Neuron (Nerve Cell) – in brain and spinal cord Long and branchy shape allow for nerve impulses to be transmitted quickly between cells Function is to carry nerve impulses throughout body

Examples of Specialized Cells Muscle Cells Long and slender, contains many mitochondria Can contract and expand to allow for movement

Examples of Specialized Cells Sperm Cells Small head that contains enzymes (breaks through egg to fertilize it), contains many mitochondria, and has tail for swimming Carries male genetic information and “swims” to egg to allow fertilization to occur

Cell Communication Goal 2.02

Cell communication Organisms are organized: – Cells  Tissues  Organs  Organ Systems Similar cells MUST be able to work together and send signals to each other

Direct Contact Cell membranes are linked Pass signals through membranes Ex: Cardiac (Heart) cells are connected and signals are passed from one cell to another

Direct Contact Plant cells have holes in their cell walls (called plasmodesmata) Pass signals and nutrients from cell to cell

Indirect contact Cell membrane has receptor proteins Receptor proteins receive signals from other cells When the signals bind to the protein, reactions occur Signals Receptor Protein Reaction

Indirect contact Hormones – Chemicals released from one part of the body that affects another – Hormones are usually released from glands – Hormones travel through bloodstream – Examples: Testosterone and Estrogen Hormones released by neurons (nerve cells) are called neurotransmitters – Examples: Serotonin and Dopomine (affects mood)

Sending Neuron Receiving Neuron Vesicle Mitochondria Synapse Cell membrane Neurotransmitter

Hormone control Negative Feedback Systems – An action that leads to the reduction of the action – SAY WHAT?! Ex: Air conditioning in your home Action: A/C leads to reduction of A/C Home is hot Air Conditioning turns on Home cools down Air conditioning turns off

Pancreas detects lowered glucose – releases glucagon Glucagon binds to liver and muscles and tells them to release glucose Glucose in Blood stream increases Pancreas detects high glucose – releases insulin Insulin tells liver and muscles to absorb glucose Glucose levels decrease Example - Eating

Brain releases hormones FSH and LH to testis Sperm are produced Testosterone is released by sperm Testosterone tells brain to stop FSH and LH Sperm stop being produced MALES

Brain releases hormones FSH and LH to ovaries Eggs are produced Estrogen is released by eggs Estrogen tells brain to stop FSH and LH Eggs stop being produced FEMALES

Water in blood decreases Hypothalmus detects and releases hormone ADH ADH travels to kidneys and other body parts Kidneys STOP removing water from blood Water in blood increases Hypothalmus detects and stops releasing ADH