Download What are Stem Cells? - HRSBSTAFF Home Page

What are Stem Cells?
Biology 11
Stem Cells
 Basically, stem cells are cells that are not assigned a functional
job in the body. (Undifferentiated cells)
 We can use stem cells to repair or replace functional cells
that are damaged or destroyed.
 Some tissues are too complex to reproduce if the need arises,
so in some cases, these tissues have stem cells for this
purpose. (ie; Bone Marrow)
Types of Stem Cells
 There are two types of stem cells:
 adult and embryonic stem cells.
 Adult stem cells turn into many different cells of the same
basic kind.
 Embryonic stem cells can turn into almost all of the body's
cell types with a few exceptions.
Potency
 Stem Cells have three different types of potency, based on the number
and types of cells they can differentiate into. There are:
 Totipotent
 These cells are those that have not begun the process of differentiation. These cells
have the capability to differentiate into any type of cell within the body.
 Pluripotent
 Almost as potentent as the previous, , these cells have barely started the
differentiation process and are capable of developing into any other type of body
cell.
 Multipotent
 Multipotent stem cells are those cells that have begun the process of
differentiation into general cell type. They can develop into certain type of cells in
a particular group or family of cells.
 Stem cells are in all of our body and lives, but are far more
potent in a fetus than in an adult body.
 Some types of stem cells may be able to create all other cells
in the body. Others have the potential to repair or replace
damaged tissue or cells.
 Embryonic Stem Cells are developed from a female egg after
it is fertilized by sperm. The process takes 4-5 days.
Stem Cell Controversy
 The controversy surrounding stem cell research led to an
intense debate about ethics.
 Up until the recent years, the research method mainly
focused on Embryonic Stem Cells, which involves taking
tissue from an aborted embryo to get proper material to
study. This is typically done just days after conception or
between the 5th and 9th week.
Stem Cell Controversy
 Since then, researchers have moved on to more ethical study
methods, such as Induced Pluripotent Stem Cells (iPS). iPS
are artificially derived from a non-pluripotent cell, such as
adult somatic cells.
 This is probably an important advancement in stem cell
research, since it allows researchers to obtain pluripotent
stem cells, which are important in research, without the
controversial use of embryos.
Pros
Stem cell research can potentially help treat a range of medical
problems. It could lead humanity closer to better treatment and
possibly cure a number of diseases:
Parkinson’s Disease
Alzheimer’s Disease
Heart Diseases, Stroke and Diabetes (Type 1)
Birth Defects
Spinal Cord Injuries
Replace or Repair Damaged Organs
Reduced Risk of Transplantation (You could possibly get a copy of
your own heart in a heart-transplantation in the future
 Stem cells may play a major role in cancer







Better treatment of these diseases could also give significant social
benefits for individuals
Cons
 "We should not mess with human life.“
 "Humans should not be trying to play God“
 Some argue that stem cell research in the far future can lead
to knowledge on how to clone humans. It is hard to say
whether this is true, but we have seen devastating
consequences of other research-programs, even with good
intentions, such as nuclear research.
Quiz Review
Biology 11
Review Questions
 What is Abiogenesis?
 Who was the first to propose abiogenesis?
 What is Biogenesis?
 Who stated that mice could formed from a dirty shirt?
 Which scientist put an end to the belief of Abiogenesis?
 Which Organelle contains the following:


A plastid usually found in plant cells
Contain green chlorophyll where photosynthesis takes place
Review Questions
 Which Organelle is this?
 What are the differences between plant and animal cells?
 What are the three parts of the cell theory?
What is Abiogenesis?
 Abiogenesis is the belief that living organisms can be created,
or arise, from non living matter.
Who was the first to propose
abiogenesis?
 Aristotle
What is Biogenesis?
 Biogenesis is the principle that living organisms develop
from other living organisms and not from non living matter.
Who stated that mice could formed
from a dirty shirt?
 Jean van Helmont
Which scientist put an end to the belief
of Abiogenesis?
 Louis Pasteur
Which Organelle contains the
following:
•A plastid usually found in plant cells
•Contain green chlorophyll where
photosynthesis takes place
 Chloroplasts
Which organelle is this?
 Mitochondria
What are the differences between
plant and animal cells?
Plant Cells
Animal Cells
Have chloroplasts and cell
Walls
Do Not have chloroplasts and
cell walls
Have centrioles
Do not usually have
centrioles
Have a large central
vacuole
Do Not have a large central
vacuole
What are the three parts of the cell
theory?
 All living things are composed of one or more cells.
 The cell is the basic unit of structure and function of all living
things.
 All cells arise only from pre-existing cells.
Items to Know
 The Cell Theory
 Abiogenesis vs. Biogenesis
 Scientists and their contributions
 Cell Organelles
 Read Pages 10-20 in Text Book for Review
 Study notes and handouts!