Stem CellsGoal 3.01
-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 ApplicationsCells can be used to replace damaged cells:
a. Cardiac = heart attacksb. Liver = Hepititisc. Nerve = paralysis, brain damage or diseasesd. Insulin cells in pancreas = diabetese. 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 researchMany 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 leadsto 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
increasesPancreas
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
