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 multi-celled 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 CellsSpecialized 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 Tissues2. 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.