Transcript Cell differentiation and cell speciation

Warm up
1. Are there some cells in your body that look
different?
2. Do you think your brain cells do the same job
as your stomach cells?
3. How do you think they get to be “different”?
Bio.1.1.3: Cell differentiation
and cell speciation
Objectives:
1. Students can explain what cell
differentiation is.
2. Students can explain how
instructions in DNA lead to cell
differentiation
Word
Definition
Picture
The process by
which cells change
1. Cell
in structure and
differentiation
become capable of
(difference)
carrying out
specialized
functions.
• This occurs in
multicellular
organisms.
White blood cell
Red blood cell
As the result, cells become different
from each other.
The design and shape of a cell is very
much dictated by its function and the
conditions under which it works
Nerve cell
White blood
cell
Red blood cell
muscle cells
Stomach cell
NERVE CELLS are responsible for the
rapid conduction of messages throughout
the body. Consequently, they are very
long and have branches that enable them
to connect to other nerve cells and deliver
messages quickly.
Nerve cell
WHITE BLOOD CELLS are primarily
responsible for fighting foreign organisms that
enter the body. They have the ability to change
shape to squeeze through cell membranes to
get to damaged cells. White blood cells have
different shapes, depending on their function.
White blood cells
Because cells in tissues perform specific
functions, they often contain organelles
that are different from the ones found in
a "typical" cell.
MUSCLE CELLS are responsible for producing
movement and to maintain posture. Muscle
tissues have the ability to shorten or contract.
Muscle cellshave huge mitochondria and many
microfibers.
Because a muscle cell's length is much greater
than its width, they are frequently referred to as
muscle fibers.
Muscle cells
RED BLOOD CELLS have disk-like flattened
membranes. This shape gives them a maximum
amount of surface area while still remaining smooth
enough to slide through the smallest capillaries.
Because red blood cells are manufactured for
limited-time use, they have lost nearly all of their
internal organelles, including nuclei.
Red blood cell
Why? And How?
1. The cell differentiation is coded in DNA in the
nucleus.
2. Most of our cells cannot differentiate, but our
body produce “stem cellS” which can
differentiate, depends on its specialized needs.
How?
• With few exceptions, all of the cells in a
multicellular organism contain the same DNA.
• This is not surprising, given that organisms
develop from mitotic divisions of one original
cell, called a zygote.
• However, it is clear that there are many
different cell types in the bodies of
multicellular organisms. How do these cells
‘mature’ to take on specific roles for an
organism?
How?
• Basically, organisms begin life as a cell whose only
developmental restrictions are based on the genome it
carries.
• For instance, an early embryonic animal cell does not
have the proper genes to develop into a leaf, but it can
develop into any cell type found in the mature animal.
• Cells with such unlimited developmental potential, like
cell of very early embryos, are often referred to as
totipotent.
• As an organism develops, the processes of cell
signaling, cell determination and cellular differentiation
lead to the maturation of cells and tissues that perform
specific functions for an organism
How?
• The way in which these cells become specialized
starts out with a chemical signal.
• In response to a given signal or signals, cells can
change the way they function and develop, most
often by controlling what genes are expressed at
what time.
• This process of cellular determination and
differentiation happens most commonly in
developing embryos, where the cells don’t yet
have a specific function, but can occur in certain
cells of adult organisms.