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Lesson 7ALesson 7A Specialized Cells, Stem Specialized Cells, Stem
Cells & Cellular Cells & Cellular DifferentiationDifferentiation
Learning GoalsLearning 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.
Specialized CellsSpecialized Cells•
Specialized cells have special shapes and structures that allow them to do specific functions (jobs)
How do cells become specialized?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
Cell DifferentiationCell Differentiation
What is cell specialization?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.
What is a specialized cell?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)
A Specialized Cell: A Specialized Cell: A cell that 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
A Specialized Cell:A Specialized Cell:•
carry out a ______________________o bone cells store calcium and build
new boneo skeletal muscle cells contract to
allow movemento fat cells store energy in the form of
fato nerve cells
conduct electrical
signals or coordinate activitieso hair cells in the inner ear detect
sound vibrationso red blood cells deliver oxygen and
remove carbon dioxideo skin cells cover the body and
reduce water loss
specific job
Where do the specialized cells come from??
Stem cell
What are Stem Cells?What are Stem Cells?
•
Stem Cells: _______________________________ that can produce various specialized cells
Non-specialized cells
Human Embryonic Stem Cells Human Embryonic Stem Cells
Coloured scanning electron micrograph of human embryonic stem cells (Image: Miodrag
Stojkovic/Science Photo Library)
What are Stem Cells?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
What are Stem Cells?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
3 Types of Human Stem Cells3 Types of Human Stem Cells
1. Totipotent Stem Cells 2. Pluripotent Stem Cells
3. Adult Stem Cells
Embryonic Stem
Cells
Within 24 hrs
Within 4‐5
days
Form any type of
tissue
Form many types of
tissue
Form specific types
of tissue
After that
…
3 Types of Stem Cells: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)
•Can become _______________ of cell
2) Pluripotent stem cells (embryo –
4 to 5 days)•Can become __________________of cells, but not all types of cells
any kind
many kinds
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
3 Types of Stem Cells:3 Types of Stem Cells:
Adult Stem Cells Adult Stem Cells (Tissue 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.
Why are Stem Cells Useful?Why are Stem Cells Useful?
•
To ______________ and ______________ damaged human tissue
•
To ______________ and ______________ disease and injuries
repair replace
treat cure
How might Stem Cells be used to develop How might Stem Cells be used to develop treatments for diseases?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.
Potential Uses Potential Uses of Stem Cellsof Stem Cells
Spinal Cord Injuries
Disorders in
Brain
Limb Amputations
Heart Disease
Burns
Diabetes
The Medical Potential of Stem Cells:The Medical Potential of Stem Cells: Adult Stem Cell TransplantationAdult 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).
stem cells stem cells treat treat
diseases diseases like like
cancercancer
The Medical Potential of Stem Cells:The Medical Potential of Stem Cells: Adult Stem Cell TransplantationAdult Stem Cell Transplantation
Umbilical cord blood has a high concentration of the adult stem cells → treat childhood leukemia
(cancer in bone marrow)
Issue with Embryonic Stem Cells:Issue with Embryonic Stem Cells: Where do the Where do the embryonic stem cells embryonic stem cells come from?come from?
1.
From
human embryo left over from fertility treatments
2.
From
cloned human embryos developed in the lab
Human Embryos from In Vitro Human Embryos from In Vitro Fertilization (outside the body)Fertilization (outside the body)
Issue with Embryonic Stem CellsIssue 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.
Ethical Issues in Stem Cell Research________________ issues:
Consider the potential moral
outcomes of stem cell technologiesThe 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?
Ethical
Legal Issues in Stem Cell Research____________ 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?
Legal
Social Issues in Stem Cell Research
__________ 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?
Social