Stem cells
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KEY IDEAS In this topic, you will learn that:
FIGURE 1 Damaged skin cells can only regenerate in humans if the damage is no deeper than the epidermis layer; otherwise, scar tissue forms.
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Multicellular organisms consist of a large number of different types of cells that communicate and work together to ensure the survival of the whole organism. Each cell has a specific function, controlled by its genetic material and the chemical messengers that surround it. Damaged cells need to be replaced. For example, when the skin is damaged, each of the different cells that make up the layers of the skin (epidermis, dermis and hypodermis) along with the nerves, lymph vessels and sweat glands need to be replaced quickly before bacteria can cause damage. Each layer requires a different type of cell with their own specialised functions. The most efficient way for all of these cells to be produced at the same time is through the use of stem cells.
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stem cells are specialised cells that can differentiate into more than one type of cell the two main types of stem cells are embryonic and adult stem cells stem cells can be totipotent, pluripotent or multipotent the use of embryonic stem cells involves bioethical considerations.
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Types of stem cells Stem cells are undifferentiated cells, effectively blank canvases that can be anything the body needs them to be. Stem cells divide to produce daughter cells that can either continue as stem cells or differentiate into specialised cells with specialised functions. These unique cells have three main characteristics. Stem cells: • can continue to reproduce themselves for long periods • are undifferentiated • can produce differentiated cells with specialised functions. There are two main types of stem cells: embryonic and adult stem cells.
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stem cell
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a cell that is capable of forming different cell types
Embryonic stem cells Embryonic stem cells are found in an embryo, from a zygote to the inner cell mass of a blastocyst. These cells can use almost any part of their genetic material. This means they can become any type of specialised cell in the body and can endlessly reproduce themselves.
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BIOLOGY FOR VCE UNITS 1 & 2
OXFORD UNIVERSITY PRESS
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