I. MORPHOLOGY OF CHROMOSOMES On the basis of chromosome length and position of t

Question

I. MORPHOLOGY OF CHROMOSOMES On the basis of chromosome length and position of the centromere, normal human chromosomes have been arranged in seven groups of autosomes, A to G, and one pair of sex chromosomes, XX or XY. With these criteria, the 23 pairs are classified as follows: Group Chromosomes 1 to 3 4 and 5 6 to 12 13 to 15 16 to 18 19 and 20 21 and 22 XX or XY Use Figure 10.1 to answer the following questions: 1. A metacentric chromosome is one that has a centrally located centromere and chromosome arms with approximately equal length. Which of the human chromosomes are metacentric? Answer by giving individual chromosome numbers 2. Submetacentric chromosomes have centromeres located close to the center of the chromosome, but the chromosome arms are distinctly unequal in length. Which human chromosomes fall into this category? 3. Acrocentric chromosomes have centromeres located much nearer one end than the other, result ing in chromosome arms that are decidedly unequal in length Gone of the chromosome arms will be very short). Which of the human chromosomes are acrocentric? No human chromosomes have cent on the end telocentric, thus having only one arm. 4. Certain human chromosomes also have secondary constrictions that usually represent the site of ribosomal RNA genes (nucleolar organizing region; NOR). Morphologically, the secondary constriction separates a portion of the short arm from the main body of the chromosome. These

Explanation / Answer

1) five chromosomes are metacentric. Chromosomes 1, 3, 16, 19, 20

2) chromosomes 2, 4, 5, 6,7,8,9,10,11,17,18 and X are submetacentic

3) chromosomes 13, 14 , 15, 21, 22 are acrocentric.

4) chromosomes 13,14,15,21,22 have satellites.

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