Textbook Question
A quantitative trait ________.
a. May be one that is strongly influenced by the environment
b. Varies continuously in a population
c. May be influenced by many genes
d. Is not either off or on
e. All of the above
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13. Mendelian Genetics
Non-Mendelian Genetics
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In the context of non-Mendelian genetics, what is nondisjunction?
A
The expression of both alleles in a heterozygote.
B
The exchange of genetic material between non-homologous chromosomes.
C
The failure of homologous chromosomes or sister chromatids to separate properly during cell division.
D
The random assortment of alleles during gamete formation.
Verified step by step guidance1
Nondisjunction is a phenomenon that occurs during cell division, specifically during meiosis or mitosis, where chromosomes fail to separate properly.
In meiosis, nondisjunction can happen during either Anaphase I or Anaphase II. In Anaphase I, homologous chromosomes may fail to separate, while in Anaphase II, sister chromatids may not separate.
This failure to separate results in gametes that have an abnormal number of chromosomes, which can lead to genetic disorders in offspring, such as Down syndrome, which is caused by an extra copy of chromosome 21.
Nondisjunction is different from Mendelian genetics, which typically involves the segregation and independent assortment of alleles according to Mendel's laws.
Understanding nondisjunction helps explain certain genetic anomalies and is crucial for studying genetic diseases and their inheritance patterns.
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