Chapter 3 Review Questions:
1. What is meant by the following terms:
Homologous chromosomes- A matched pair of chromosomes, one derived from each parent. Both members of the pair are similar in size, shape, and appearance, except for sex chromosomes. Autosomes- The general term for chromosomes other than the sex chromosomes. Sex chromosome- The X and Y chromosomes that determine genetic sex. Barr body- The inactivated X chromosome that appears as a small, dense mass of chromatin attached to the nuclear membrane of somatic cells. This structure can be identified in the cells of a normal female and is called a sex chromatin body or Barr body after the man who first described it. Gene- Are segments of DNA chains that determine some property of the cell and are the basic units of inheritance. Sometimes, they are described as being arranged along the chromosome like beads on a string. Gametogenesis- A specialized type of cell division that occurs during the development of the eggs (ova) and sperm. The development of mature eggs and sperm from precursor cells. Centrosome- A small region of cytoplasm adjacent to the nucleus that contains the centrioles and serves to organize microtubules. 2. How does the process of mitosis compare with meiosis?
In mitosis, each of the two new cells (called the daughter cells) resulting from the cell division receives the same number of chromosomes that were present in the precursor cell (called the parent cell). In meiosis, the number of chromosomes is reduced so that the daughter cells receive only half of the chromosomes possessed by the parent cell. This process is not completed until fertilized by the sperm. 3. What are the differences between spermatogenesis and oogenesis? First, four spermatozoa are produced from each precursor cell in spermatogenesis, but only one ovum is formed from each precursor cell in oogenesis. The other three “daughter cells” derived from the meiotic divisions are discarded as polar bodies....
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