Cell Specialization

Cells, Tissues and Organs

Why Specialize?

• A single cellular organism performs all required functions in one cell.

• e.g., Amoeba.

Why Specialize?

• Multicellular organisms are much more complex.

• The body needs to supply food and nutrients, transport materials, remove wastes and fight infection.

Cellular Differentiation

• The process of creating specialized cells.

• All cells in the body originated from the zygote undergoing mitosis.

• As an embryo develops, cells change their shape, contents and function.

Cellular Differentiation

What Causes Specialization?

1. Cytoplasm Differences:

• Asymmetric distribution of organelles & other factors in zygote.

• Results in different daughter cells.

What Causes Specialization?

2. Environmental Conditions:

• Variations in temperature and nutrients.

3. Neighbouring Cells:

• Substances produced by nearby cells can diffuse to nearby cells.

What Causes Specialization?

• The three factors listed may result in the expression of different genes within a cell.

Abnormal Development

• Chemical contamination of the environment can affect cellular development.

Stem Cells

• Cells that can differentiate into many different cell types.

• The daughter cells have the same DNA, but different genes may be turned on or off.

Watch This!!!

Types of Stem Cells

1. Embryonic Stem Cells

– Differentiates into any cell type.

2. Adult Stem Cells

– Exists in some tissues but can only form specific types of cells.

– E.g., bone marrow stem cells form white blood cells, red blood cells and platelets.

Stem Cell Research

Tissue Types

• Tissues are a collection of similar cells that perform specific functions.

• Animals have 4 types of tissue:

1. Epithelial.

2. Muscular.

3. Connective.

4. Nervous.

Epithelial Tissue

• Line the internal and external surfaces of the body.

• Form a barrier by connecting adjoining cell membranes.

Muscular Tissue

• Move the body or organ by contracting and relaxing.

Connective Tissue

• Strengthens, supports and protects other tissues.

• Cells are in an extracellular matrix.

Nervous Tissue

• Made of neurons with long projections that send and receive signals.

• Coordinates body actions.

Tissues in the Arm