GENETICS AND EVOLUTION
GENETIC BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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deletion and inversion
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linking and unlinking
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recombination
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formation of a Barr body
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Detailed explanation-1: -Errors can occur during meiosis producing gametes with an extra or missing chromosome. The consequences of this following fertilisation depend on which chromosomes are affected. Often the embryo is not viable, but some of these errors can lead to trisomy conditions or sex chromosome disorders.
Detailed explanation-2: -Deletions. Deletions occur when a chromosome breaks and some genetic material is lost. Deletions can be large or small, and can occur anywhere along a chromosome.
Detailed explanation-3: -In a female fetus, an extra X chromosome causes Triple X syndrome. It is associated with learning disabilities and organ abnormalities. In a male fetus, Klinefelter syndrome is the result of an extra X chromosome (XXY). Males with this condition have smaller testicles and are infertile.
Detailed explanation-4: -Chromosomes may break “spontaneously” or by the effects of chemical and physical agents (ionizing radiation). The breakage may involve only one of the chromatids or both (isochromatid breaks) (see Fig. C87).