L4 –Cell Specialization
(Types of Cells)
Grade 10 Science
Nicole Klement
Multi-cellular Organisms
• Living things can be as simple as
single-celled organisms such as a
Paramecium or an Amoeba that lives
in pond water or as complex as multicelled organisms such as humans.
• The cells in a multi-celled organism
are specialized so that they can
perform specific functions for the
organism.
• Larger organisms contain more cells
and require more complex methods to
carry out their life processes.
• Red blood cells are one type of cell
found in the human body. Mature red
blood cells no longer have a nucleus
so they do not have the ability to
divide.
Did you know?
• Did you know that about 2 million red
blood cells die in the human body every
second? Approximately the same numbers
are formed in the bone marrow each
second.
Cell Specialization
•
•
You are an independent living being, just like a cell. You perform all the
functions necessary to maintain your life, just like a cell. While there are
some people who can live completely alone, just as there are a few
single-celled organisms, the majority of people need to live in a society;
so do cells. And just as people have specific roles in a society, such as
teachers, doctors, and bus drivers, cells also have specific roles within
the organism they belong to, such as nerve cells, muscle cells, and
blood cells. The parallels in Creation are wondrous!
Just like people within a community, cells within an organism have
different roles. This is known as cell specialization. This begins to
happen very early on in an organism's development. It can be as early
as the first few divisions of an embryo. Embryonic stem cells can divide
to produce copies of themselves, or they can produce more specialized
cells. The process that causes this is still not known for sure, but
scientists think that it has to do with the presence of certain proteins
that trigger parts of the DNA in cells. The DNA determines what a cell
will become, and what it will do.
Cell Specialization
Although we begin as a single fertilized cell,
we contain many different cells:
• blood cells,
• skin cells,
• bone cells,
• muscle cells,
• and nerve cells.
The process by which cells become
specialized is called differentiation. Cells
that are specialized will possess unique
structures and functions. Cell
differentiation leads to a multi-cellular
organism with a greater efficiency for
performing different tasks.
Did you know?
• Did you know that the human brain has
more than 100 billion nerve cells? Once
brain cells are damaged they do not
readily regenerate and replace
themselves.
Specialized Cells
Specialized cells have unique features that enable
them to perform their tasks.
For example, red blood cells lose their nuclei, and
contain a substance known as haemoglobin that
allows them to transport oxygen.
On the other hand, white bloods cell keep their
nuclei as this makes it easier for them to adapt
to new threats in the body.
Cells in the stomach produce hydrochloric acid so
that you can digest your food.
Nerve cells are encased in a protein coating known
as a myelin sheath that contains the electrical
impulses they generate.
As a result, specialized cells look different from one
another.
Group Activity
•
In a group answer the following question:
1. Why is it important that our cells
differentiate?
2. List some of the different types of cells
found in the human body.
3. Describe the structure and function of
one of those types of cells.
Specialized Tissues
Specialized cells come together to form tissues.
Tissues are groups of cells with the same types of
specialization. They do the same job, so they
often can be found together.
Lung tissue is composed of cells that are
specialized to facilitate the transfer of oxygen
inside your body and carbon dioxide out of your
body.
You will only find lung tissue in the lungs.
Four Types of Tissues
1. Epithelial Tissue: These
tissues pack together tightly to
form membranes that line
different parts of the body.
• Epithelial tissues keep the
body's organs in place and
protected, for example, the
mesenteric lining contains your
intestines. Your skin is also
epithelial tissue and contains
everything!
• The skin cells are flat and
packed tightly together.
Four Types of Tissues
2. Muscle Tissue: Muscle
tissue can contract and can
slide past one another.
When they contract, they pull
on the tendons and
ligaments that connect them
to bones, which cause the
bones to move.
This allows your body to move.
• Notice how the cells are
long, thin and tapered.
Four Types of Tissues
3. Nerve Tissue: Nerve tissue contains
two types of cells, neurons and glial
cells.
Neurons generate and conduct electrical
impulses in the body and glial cells
support and nourish the neurons. The
electrical impulses are controlled by
the brain and are sent to the rest of the
body through the spinal cord.
Notice how the nerve cell of a rat is long
and branched.
Four Types of Tissues
4.Connective Tissue: Connective
tissue supports the body, and
gives it structure.
Most types of connective tissue
contain collagen, a type of protein.
Tendons, ligaments, cartilage, bone,
and fat tissue are all examples of
connective tissue.
Blood is also considered a form of
connective tissue.
Notice how closely packed the bone
cells are.
Resources
•
Cell Specialization
•
http://www.beyondbooks.com/lif71/4h.asp
•
Pictures of Cells
•
http://www.edquest.ca/component/content/article/181
Levels of Biological Organization
•
The levels of biological organization begin with the simplest
level, the cell, and end with the most complex level, the
organism.
The levels of biological organization include:
• Organism
↑
Organ System
↑
Organ
↑
Tissue
↑
Cell
The heart is an organ made up of many different types of
tissues working together to pump blood throughout the
human body.
Organs & Organ systems
• The digestive system is made up of several
organs that perform specific functions to ensure
that food is broken down, called digestion, so that
it can be used by the cells.
• Some of the organs of the digestive system
include:
• the mouth,
• the esophagus,
• the stomach,
• the small intestine,
• the colon,
• the pancreas,
• and the liver.
Did you know?
• Did you know that the skin is the largest
organ of the human body?
• In 2.5 square centimetres of skin, there
are approximately 100 sweat glands,
almost 3 metres of blood vessels, and 3
million cells.
Organ systems
Other organ systems include:
• the circulatory system,
• The respiratory system,
• the nervous system.
Each organ system has a specific job in
maintaining homeostasis (constant internal
conditions) within the organism.
Organ Systems
• When one of the organs in an organ system fails
to function properly it will affect the entire
system.
• This could lead to serious consequences on the
performance of the organism and may even be
the cause of death.
• For example, a heart attack may damage or
destroy a section of the heart and impair the
functioning of this organ, which in turn affects
the entire organism because the heart can no
longer work to pump blood around the body.
Did you know?
• Did you know that approximately 11.5
litres of digested food, liquid, and digestive
materials move through the digestive
system each day?
• Only about 100 mL of fluid is lost in the
feces each day.
Group Activity
Answer the following questions in your
groups
1. List the levels of biological organization
from simplest level to most complex.
2. Name three organ systems.
3. Will the organ system continue to
function if one of the organs is not
working properly? Explain.
Group Activity
Discuss the following with your classmates.
1. Why do you think it is necessary for cells
to be specialized?
Definitions - reviewed
• Cells: are the basic structural units of life.
• Tissues: Blood is a tissue, where different kinds
of blood cells are grouped together to transport
oxygen, nutrients, wastes, and other materials
throughout the body.
• Organs: The heart is an organ made up of many
tissues. For example, the muscle tissue in the
heart is responsible for pumping the blood
throughout the body and the nervous tissue
coordinates the muscular activity of the heart.