Disruption to the cell cycle
3.4
KEY IDEAS In this topic, you will learn that: ✚ ✚
the action of mutagens or genetic predispositions can disrupt the cell cycle disruptions of the cell cycle can result in uncontrollable cell division such as cancer malfunctions in apoptosis can produce deviant cell behaviour.
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The cell cycle generally functions very efficiently, but sometimes it malfunctions, which can cause many issues for an organism. For example, every time a cell replicates its DNA, approximately three errors occur. Most of these errors are detected and repaired, but some remain and become permanent (mutations). DNA can also become damaged through normal metabolic activities or by environmental factors such as radiation or chemicals. Cells themselves can become damaged through complications with apoptosis.
Mutagens
Mutagens are agents that cause a permanent change in the DNA sequence. Mutagens include radiation, chemicals and biological agents. Many mutagens can cause deviant cells that eventually lead to cancer or characteristics of cancer cells.
mutagen
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Radiation
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something that causes a mutation, either chemical, physical or biological
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Radiation is a form of energy that consists of electromagnetic waves or high-energy particles. Some forms of radiation (such as radio waves) are very low energy and harmless, whereas others (such as UV light or X-rays (Figure 1)) can cause changes in the DNA sequence.
FIGURE 2 Cigarette smoke contains chemicals that cause DNA mutations.
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BIOLOGY FOR VCE UNITS 1 & 2
FIGURE 1 X-rays can cause DNA mutations.
Chemicals Chemical agents include some of the chemicals in cigarette smoke (Figure 2), mustard gas (which has been used in chemical warfare) and nitrogen oxides. These chemicals react with the genetic material in cells, resulting in a permanent change in the DNA sequence.
OXFORD UNIVERSITY PRESS
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