Bio-Pac 05: Objective 07-10 Flashcards
Objective 7. List and describe the phases of meiosis 1.
In meiosis 1 there is the interphase, prophase 1, metaphase 1, anaphase 1, and telophase 1. In interphase the cell replicates its chromosomes, so then there is two identical chromatids that are held together by a centromere. In prophase 1, the chromosomes coil up, spindle forms, each pair of homologous chromosomes comes together to form a four part structure called a tetrad (two homologous chromosomes). In metaphase 1 the tetrads line up on the midline or equator of the spindle. In anaphase 1 the homologous chromosomes separate and move to opposite poles. (The centromere does not split). In telophase 1 event occur in reverese order from the events on prophase 1. The spindle is broken down, the chromosomes uncoil, and cytoplasm divides to yield new cells (each cell has only half the genetic information as the original cell).
Objective 8. List and describe the phase of meiosis 2.
Meiosis 2 is basically like mitosis, except there is no replicating. In meiosis 2 there is prophase 2, metaphase 2, anaphase 2, and telophase 2. In prophase 2 the spindle forms in each of the two new cells. In metaphase 2, the chromosomes (still made up of sister chromatids) line up at the equator. In anaphase 2, the centromere of each chromosome then splits and the sister chromatids and move to opposite poles. In telophase 2 the spindle disappears, the chromosomes uncoil, and the nucleus and nuclear membrane reappear. At the end of meiosis 2 there are four haploid cells that formed from two diploid cells. Each haploid cell contains one chromosome from each homologous pair. These haploids will become gametes.
Objective 9. Differentiate between meiosis in male and female formation.
When meiosis 2 is over the haploid cells will become gametes. In sperm formation, one diploid cell produces four sperm. In ovum formation one diploid cell produces one ovum. In ovum formation there would have been four ovums formed but three die which allows only one ovum (haploid cell) to be produced. Sperm and egg formation occur in different places and separate times.
Objective 10. Explain when both the process of mitosis and meiosis are performed in a multicellular organism.
In a multicellular organism mitosis and meiosis are performed at the same time. Mitosis will be occurring in the somatic cells/body cells while meiosis will occur in the gamete cells. Because both mitosis and meiosis are occurring in different types of cells and one is not relied on the other, both processes can occur at the same time in a multicellular organism.
