How is aneuploidy different from polyploidy? What are the mechanisms by which aneuploidy and polyploidy are caused, and what are the consequences of these chromosomal alterations in terms of survival and fertility of the offspring?
What will be an ideal response?
Aneuploidy occurs when one or more chromosomes are lost or gained relative to the normal euploid number. Chromosome nondisjunction is a principal cause of aneuploidy. Nondisjunction can occur in somatic cells or in germ-line cells with similar results. If a single pair of homologous chromosomes fails to properly disjoin in a somatic cell during mitotic cell division, one of the resulting daughter cells carries an extra chromosome (2n + 1), and the other is missing a chromosome (2n – 1). Mitotic cells of animals that contain the wrong number of chromosomes may suffer reduced viability, although cells with abnormal numbers of chromosomes are common in cancer where other alterations of chromosome number play a central role in cancer cell survival and proliferation.
Polyploidy is the presence of three or more sets of chromosomes in the nucleus of an organism. Polyploidy in nature can result either from the duplication of euploid chromosome sets from a single species or from the combining of chromosome sets from different species.
Polyploids whose karyotype is comprised of chromosomes derived from a single species are designated as autopolyploids (auto = "self"), and polyploids with chromosome sets from two or more species are called allopolyploids (allo = "different"). Polyploidy is common in plant species but is extremely rare in animals; it is caused by multiple fertilization, mitotic nondisjunction, or meiotic nondisjunction.
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A. cytoplasm. B. nucleoplasm. C. ribosome. D. stroma.
Chondroblasts produce ________
Fill in the blank(s) with correct word
The head of a giraffe is 5 meters above its heart. Compared to humans, giraffes have
A) higher systolic blood pressure. B) less blood volume. C) lower systolic blood pressure. D) veins of smaller diameter.
Which of the following statements is correct about passive diffusion?
A) It requires an expenditure of energy by the cell. B) It is a process in which molecules move from a region of higher concentration to a region of lower concentration (or down a concentration gradient). C) It is a process in which molecules move from a region of lower concentration to one of higher concentration (or up a concentration gradient). D) It may require a transport protein. E) It involves movement of molecules down a concentration gradient and may require a transport protein.