Animal Physio

Lacei Machelle Gallemit

BS BIO III

1. What is a chromosome?

In eukaryotes, a DNA molecule that contains genes in linear order to which numerous proteins are bound and that has a telomere at each end and a centromere; in prokaryotes, the DNA is associated with fewer proteins, lacks telomeres and a centromere, and is often circular; in viruses, the chromosome is DNA or RNA, single-stranded or double-stranded, linear or circular, and often free of bound proteins.

2. What is the significance of chromosome 2 in human evolution?

3. What is a telomere? What is a centromere? How were these used to prove human’s common ancestry with apes?

A telomere is the tip of a chromosome, containing a DNA sequence required for stability of the chromosome end. A centromere on the other hand is the region of the chromosome that is associated with spindle fibers and that participates in normal chromosome movement during mitosis and meiosis.

4. Do you find the interpretation of chromosome 2 convincing evidence that humans share a common ancestry with other great apes? Explain.

Among higher primates, chimpanzees and human beings have 22 pairs of chromosomes that are morphologically similar, but chimpanzees have two pairs of acrocentrics not found in human beings, and human beings have one pair of metacentrics not found in chimpanzees. In this case, human metacentric chromosome was formed by fusion of the telomeres between the short arms of the chromosomes that, in chimpanzees, remain acrocentrics. The fusion was accompanied by the inactivation, by an unknown mechanism, of one of the centromeres, so that the fused chromosome has only a single functional centromere. The metaphase chromosome resulting from the fusion is human chromosome 2, and it reduces the chromosome number 48, which is characteristic of the great apes, to the number 46 present in the human genome.

5. Knowing what you know now, do you think a hybrid could be produced between a chimp and a...