1. True or False – If a deletion occurs involving the centromere, segregation is
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Question
1. True or False – If a deletion occurs involving the centromere, segregation is impossible and the chromosome is lost
2. Which type of chromosome has the longest p arm?
3. A chromosome exchanges a segment of genetic material with another non-homologous chromosome. What kind of translocation is this?
4. True or False – Pericentric inversions involve the centromere
5. Which of the following is a terminal tandem duplication? Assume the original chromosome reads: ABCD EFGH a. ABCDCD EFGH b. ABCD EFFEGH c. ABABCD EFGH
6. True or False – Homozygous individuals with chromosomal mutations experience more meiotic difficulties than those that are heterozygous
Explanation / Answer
1. FALSE : A DELETION is simply the loss of a part of one chromosome arm. The process of deletion requires two chromosome breaks to cut out the intervening segment. The deleted fragment has no centromere; consequently, it cannot be pulled to a spindle pole in cell division and will be lost. The effects of deletions depend on their size. A small deletion within a gene, called an intragenic deletion, inactivates the gene and has the same effect as other null mutations of that gene. If the homozygous null phenotype is viable (as, for example, in human albinism), then the homozygous deletion also will be viable. Intragenic deletions can be distinguished from single nucleotidechanges because they are nonrevertible.
2 A centromere is a region of a chromosome that separates it into a short arm (p) and a long arm (q). The chromosome consists of two identical structures called sister chromatids, which are joined at the centromere.
p arm is called acrocentric chromosome .
3. reciprocal translocations, the most common type. A segment from one chromosome is exchanged with a segment from another nonhomologous one, so two translocation chromosomes are generated simultaneously. The exchange of chromosome parts between nonhomologs establishes new linkage relations.
4. Pericentric inversions include the centromere and there is a break point in each arm.
5. (C) ABABCDEFGH
6 FALSE hetero zygous pairing more difficulties during meiosis
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