This document provides information about cell differentiation from a lecture presented by Dr. SHWETA SINGH. It defines cell differentiation as the process by which a cell undergoes changes in gene expression to become a more specialized cell type. This allows multicellular organisms to develop uniquely functional cell types and body plans. The document discusses how all organisms begin as a single cell and must undergo cell division and differentiation to form the complex tissues and organ systems of the adult body. It provides examples of cell differentiation in animal development and plant growth from a single cell.

1. Dr. SHWETA SINGH
Assistant Professor
Applied Sciences
Suresh Gyan Vihar University
Jaipur

2. Cell Differentiation
Cellular differentiation, or simply cell
differentiation, is the process through which a
cell undergoes changes in gene expression to
become a more specific type of cell.
The process of cell differentiation allows multi-
cellular organisms to create uniquely functional
cell types and body plans. The process of cell
differentiation is driven by genetics, and their
interaction with the environment.
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3. • All organisms begin from a single cell.
• This single cell carries the DNA coding for all
the proteins the adult organism will use.
However, if this cell expressed all of these
proteins at once it would not be functional.
• This cell must divide repeatedly, and the cells
must begin the process of cell differentiation
as they divide.
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4. • The original mass of cells, which have not undergone
differentiation, are known as stem cells.
• Unlike normal cell division, which creates two
identical daughter cells, the division of stem cells is
asymmetric cell division.
• In this case, one of the cells remains identical to the
parent stem cell.
• In the other cell, chemical triggers activate the
process of cell differentiation, and the cell will start
to express the DNA of a specific cell type. Stem cells
which can differentiate into entire organisms are
known as embryonic stem cells and are said to be
totipotent.
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5. Cell Differentiation Examples
• After the process of fertilization in animals, a single-
celled organism called the zygote is formed.
• The zygote is totipotent, and will eventually become
an entire organism. Even the largest animal on Earth,
the blue whale, starts as a single cell. The complex
tissues and organ systems, which are completely
different in their form and function, all come from
the zygote. The process of cell differentiation starts
early within the organism. By the time the gastrula
has formed, the cells have already started expressing
various portions of the DNA
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6. • While the plant lifecycle sometimes seems alien and
complex, the process of cell differentiation is very
similar.
• While there are different hormones involved, all
plants also develop from a single cell. A seed is
simply a protective housing for the zygote, which
also provides a food supply. It is very similar to an
egg in the animal world.
• The zygote inside undergoes cell division, and
becomes a small embryo. Development is halted, as
the seed is distributed into the world.
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7. Cell Differentiation Process
• One of the keys to the cell differentiation process is
transcription factors.
• This complex process is still being studied. Scientist
have made considerable advances in understanding
cell differentiation, starting with the complete
understanding of the nematode C. elegans. This tiny,
worm-like creature has a total of 959 cells as an adult
female.
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8. • With such a small number, they are relatively
easy to track from the zygote to the adult.
Tracing their cell lineage, scientists have
started to determine some of the complex and
epigenetic forces working on cell
differentiation. In other words, it matters not
only what DNA a cell has, but where and how
that DNA is expressed.
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9. • 1. Why is cell differentiation an important process?
A. It allows for multi-cellular life forms
B. It creates new species
C. We could do without it
A is correct. Without the process of cell differentiation,
multicellular organisms would not be possible. Some
algae live in colonies, but this is nowhere near the level
of complexity developed by insects or vertebrates. Cell
differentiation allows the creation of tissues and
organs, which can serve specific and useful functions
for an organism.
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10. • 2. What is the difference between cell
differentiation and development?
A. Development does not include differentiation
B. Cell differentiation is part of development
C. There is no difference
• B is correct. Development is the entire process of
creating a new organism from a single cell. It includes
everything from forming the correct tissues to
creating the neural connections to support a new
body. Cell differentiation is simply the process
through which cells begin to express only certain
portions of DNA, thereby becoming specialized cell
types.
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What are stem cells?
Stem cells: The body's master cells
Stem cells are the body's raw materials — cells from which
all other cells with specialized functions are generated.
Under the right conditions in the body or a laboratory, stem
cells divide to form more cells called daughter cells.
These daughter cells become either new stem cells or
specialized cells (differentiation) with a more specific
function, such as blood cells, brain cells, heart muscle cells
or bone cells. No other cell in the body has the natural
ability to generate new cell types.

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Why is there such an interest in stem cells?
Researchers hope stem cell studies can help to:
•Increase understanding of how diseases occur. By
watching stem cells mature into cells in bones, heart
muscle, nerves, and other organs and tissue,
researchers may better understand how diseases and
conditions develop.
•Generate healthy cells to replace cells affected by
disease (regenerative medicine). Stem cells can be
guided into becoming specific cells that can be used in
people to regenerate and repair tissues that have been
damaged or affected by disease.
•People who might benefit from stem cell therapies
include those with spinal cord injuries, type 1 diabetes,
Parkinson's disease, amyotrophic lateral sclerosis,
Alzheimer's disease, heart disease, stroke, burns,
cancer and osteoarthritis

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Where do stem cells come from?
There are several sources of stem cells:
•Embryonic stem cells. These stem cells come from embryos that
are 3 to 5 days old. At this stage, an embryo is called a blastocyst and
has about 150 cells.
•These are pluripotent (ploo-RIP-uh-tunt) stem cells, meaning they can
divide into more stem cells or can become any type of cell in the body.
This versatility allows embryonic stem cells to be used to regenerate or
repair diseased tissue and organs.
•Adult stem cells. These stem cells are found in small numbers in
most adult tissues, such as bone marrow or fat. Compared with
embryonic stem cells, adult stem cells have a more limited ability to
give rise to various cells of the body.
•Until recently, researchers thought adult stem cells could create only
similar types of cells. For instance, researchers thought that stem cells
residing in the bone marrow could give rise only to blood cells.

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25. • Mayo Clinic on Stem Cells therapy
• California Institute for regenerative medicine
• Stem Cell research paper (PubMed)
• Stem cell Research and Therapy (Biomed
Central)
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THANKS