Demonstration

U sing the oil immersion objective of a microscope, see if you can locate some human chromosomes by examining a prepared slide of human chromosomes from leukocytes. The cells on this slide were cultured in a special medium and were stimulated to undergo mitosis. The mitotic process was arrested in metaphase by exposing the cells to a chemical called colchicine, and the cells were caused to swell osmotically. As a result of this treatment, the chromosomes were spread apart. A complement of human chromosomes should be visible when they are magnified about 1,000x. Note that each chromosome is double-stranded and consists of two chromatids joined by a common centromere (fig. 6.4).

Figure 6.4 A complement of human chromosomes (2,700x). How many chromosomes does a human cell contain? A karyotype can be constructed by arranging the homologous chromosome pairs together in a chart.

Figure 6.4 A complement of human chromosomes (2,700x). How many chromosomes does a human cell contain? A karyotype can be constructed by arranging the homologous chromosome pairs together in a chart.

Girdle Wearers
Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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