1. Explain how polyploidy is different from aneuploidy. 2. Contrast autopolyploi
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Question
1. Explain how polyploidy is different from aneuploidy.2. Contrast autopolyploidy with allopolyploidy
3. List potential factors that contribute to increased aneuploidy risk with advanced maternal age.
4. Explain the inheritance pattern of familial Down syndrome
5. Describe the genetics of Down syndrome, and contrast primary Down syndrome with familial Down syndrome.
6. Describe the role of chromosome rearrangements (duplications, deletions, inversions, and translocations) and polyploidy in the process of evolution. 1. Explain how polyploidy is different from aneuploidy.
2. Contrast autopolyploidy with allopolyploidy
3. List potential factors that contribute to increased aneuploidy risk with advanced maternal age.
4. Explain the inheritance pattern of familial Down syndrome
5. Describe the genetics of Down syndrome, and contrast primary Down syndrome with familial Down syndrome.
6. Describe the role of chromosome rearrangements (duplications, deletions, inversions, and translocations) and polyploidy in the process of evolution.
2. Contrast autopolyploidy with allopolyploidy
3. List potential factors that contribute to increased aneuploidy risk with advanced maternal age.
4. Explain the inheritance pattern of familial Down syndrome
5. Describe the genetics of Down syndrome, and contrast primary Down syndrome with familial Down syndrome.
6. Describe the role of chromosome rearrangements (duplications, deletions, inversions, and translocations) and polyploidy in the process of evolution.
Explanation / Answer
1) Organisms having two sets of homologous chromosomes are called Diploid. Polyploidy is a condition of having more than two sets of homologous chromosomes in a cell. Occurs due to abnormalities during cell division ( mitosis and meisis). polyploidy is rare in humans more common in plants. Triploid (occurs in watermelon, apple, banana e.t.c) , tetraploid (peanut, tobacco, kinnow e.t.c) are the different types of polyploidy.
Aneuploidy is a condition of having extra number or absence of chromosome in a cell. More common in humans. Anueploidy leads to genetic disorders. improper seggregation of chromatids during the gamete formation leads to anueploidy. Monosomy 2n-1 (Turner's syndrome, 45+X), Trisomy 2n+1 ( Down syndrome) are the example of anueploidy.
2) Autopolyploidy is a type of polyploidy where the cell has more than two sets of homologous chromosomes derived from the same species. Chromosomes are homologous in nature. Mainly caused by non-disjunction of chromosomes.
Allopolyploidy is a type of polyploidy where the cell has more than two sets of homologous chromosomes derived from the same species. Chromosomes are non-homologous in nature. Mainly caused by mating of different species.
3)
4) Down syndrome is a chromosomal disorder characterised by the presence of an extra copy of a whole or part of the 21st chromosome in a cell. Due to non disjunction during cell division, gamete is formed with an extra copy of 21chromosome. When this gamete combined with a gamete from the other parent, the child has now 47 chromosomes, with three copies of 21chromosome.
people with translocation down syndrome will inherit the condition from unaffected parent. The parent carries a rearrangement of genetic material known as balanced translocation between chromosome 21 and another chromosome. Neither gain or loss of genetic material occured in a balanced translocation, so these chromosomal changes usually do not cause down syndrome in the first generation. However, as this translocation is passed to the next generation, it can become unbalanced. Peoples inherited with an unbalanced translocation involving chromosome 21 may have extra genetic material from chromosome 21, which leads to Down syndrome.
5) Down syndrome result from trisomy of chromosome 21, which means that each cell of the body has three copies of chromosome 21 instead of the usual two copies.
Familial down syndrome is similar to the primary down syndrome in that it causes due te trisomy of 21 chromosome. In contrast to the primary one famililial down syndrome occured due to translocation of whole or part of a chromosome 21 onto the chromosome 14. one of the parent of the affected child is the carrier of the translocated chromosome ( translocated parent is not affected because he or she has total of two copies chromosome 21.
6) In polyploidy, the increased number of alleles of a given gene allows the masking effect of deleterious recessive mutations which insures against the loss of fitness (Gu et al., 2003). In polyploids sduplicated gene copies can evolve to assume new or slightly varied functions which allows for ecological niche expansion or increased flexibility in the organism's response to the environmental change.
Chromosomal rearrangements ( deletion or addition) ensures the adaptation of cell to the changing enviroment. retroposons are a means of evolutionary adaptation to environmental changes.
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