UNIT
3
The transmission of traits
MUTAGENIC AGENTS
Biology and Geology 4. Secondary Education.
UNIT
3
Mutagenic agents
Many mutations are not spontaneous; instead they are due to
the action of mutagenic agents or physical and chemical
mutagens.
PHYSICAL
MUTAGENS
CHEMICAL
MUTAGENS
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Biology and Geology 4. Secondary Education
UNIT
3
Mutagenic agents
Physical mutagens
Ultraviolet radiation. This is
electromagnetic radiation which is low
in wavelength. It provokes a reaction
between two contiguous bases, which
form cytosine or thymine dimers. This
stops these bases being able to
combine with the complementary base
and, furthermore, paralyses
replication. They provoke skin
wounds.
Ionising radiations. X-rays, γ rays,
etc., can lead to the breaking up of the
DNA structure. They affect all types of
tissues.
Biology and Geology 4. Secondary Education
It is important to protect oneself from ultraviolet
radiation from the sun; the effect of this radiation on
DNA is associated with the appearance of skin
cancer.
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UNIT
3
Mutagenic agents
Chemical mutagens
There are many chemical agents which produce mutations, and they have
diverse effects too.
Some of these compounds transfer chemical groups to the nitrogen bases,
leading to alterations in replication.
Biology and Geology 4. Secondary Education
UNIT
3
Mutagenic agents
Chemical mutagens
There are many chemical agents which produce mutations, and they have
diverse effects too.
Others interleave themselves among the pairs of DNA bases and deform the
double helix structure.
Biology and Geology 4. Secondary Education
UNIT
3
Mutagenic agents
Chemical mutations
There are many chemical agents which produce mutations, and they have
diverse effects, too.
And there are others which, given their analogy with a base, substitute the base
and provoke errors in the translation of the proteins.
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Biology and Geology 4. Secondary Education