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