Cell Specialization Cells, Tissues and Organs
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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
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