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7-4 The Diversity of Cellular Life

7-4 The Diversity of Cellular Life

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Copyright Pearson Prentice Hall

7-4 The Diversity of Cellular Life

The differences among living things arise from the ways in which cells are specialized to perform certain tasks and the ways in which cells associate with one another to form multicellular organisms.

7-4 The Diversity of Cellular Life

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Multicellular Organisms

Multicellular Organisms

Organisms that are made up of many cells are called multicellular.

There is a great variety among multicellular organisms.

7-4 The Diversity of Cellular Life

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From single cell to me!

Cell Differentiation

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How did that happen?

ESSENTIAL QUESTIONS:

A pancreas cell, eye cell and nerve cell in your body:

Are these cells genetically identical to each other (same # of chromosomes)?

Does an eye cell have the gene to make insulin?

Why are they different in form and function?

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What is cell differentiation?

Differentiation means that one cell performs a different function and has a specialized form than another cell, depending on where it is in your body.

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When does cell differentiation occur?

Cell differentiation occurs as cells become specialized when an embryo grows and develops.

STEM CELLS

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What are stem cells?

Stem cells are unspecialised cells that have the ability to reproduce and differentiate into a diverse range of

specialised cells.

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Types of stem cells

Embryonic Adult

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Embryonic stem cells

Embryonic stem cells are derived from an embryo about 4–5 days old (bastocyst).

These cells have the ability to differentiate into all of the cell types that make up an organism.

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Adult (tissue) stem cells

Adult or tissue stem cells are found in small numbers in the tissues and organs of adults and children, including the brain, bone marrow, skeletal muscle and skin.

These cells give rise to a much more limited range of cell types and will tend to develop into cell types that are closely related to the tissue in which they are found.

These cells replenish differentiated cells that need replaced in the tissues in which they are found.

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Other types of stem cells

Stem cells can also be taken from the umbilical cord of new babies.

Like adult stem cells, these cells can differentiate into a limited range of specialised cells.

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Early embryogenesis of the Seastar at the 2-cell and 4-cell stages (top). The cells divide asymmetrically to form the morula (bottom left) and then differentiate into a swimming larva after gastrulation (bottom right).

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MRI technology has allowed detailed 3D images of mouse and quail development.