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4 Cell replication. ‘Spray-on skin’. ODD FACT It has been estimated that each person replaces, on average, 18 kg of skin cells during a lifetime. Dandruff, skin cells from our scalps, represents just a fraction of the skin cells we must replace.
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‘Spray-on skin’ ODD FACT It has been estimated that each person replaces, on average, 18 kg of skin cells during a lifetime. Dandruff, skin cells from our scalps, represents just a fraction of the skin cells we must replace. Figure 4.4 ‘Spray-on skin’ or CellSpray, developed by Dr Fiona Wood. Skin cells taken from a patient are cultured and allowed to replicate. A suspension of these cells is sprayed onto burnt areas where they continue to grow and form a new skin.
Nuclear division leads toreproduction of cells • Cells reproduce during the cell cycle. • Cells can reproduce only if the genetic material is replicated. • The duplication of cells involves mitosis and cytokinesis. • The two newly formed cells each have the same kind and amount of genetic material as the parent cell. • Each species has a characteristic chromosome number.
How long is a cell cycle? Figure 4.9 The total time taken for one mitotic cell cycle can vary greatly from organism to organism. Note the checkpoints at which there appears to be self-checking to ensure that mistakes have not occurred during the synthesis of DNA or replication of the cell.
Mitosis occurs in a range of different tissues in different plants and animals. • Some eukaryotes reproduce asexually from a single cell. • Uncontrolled cell replication can lead to cancers.
