Tuesday, December 8, 2009

Chapter 12: The Cell Cycle


3 Main Questions
- What is cell division?
The reproduction of cells.

- How many stage are there in the Mitotic division of an animal cell?
There are 5 stages in Mitosis.

- What is genome?
The genetic information of a cell.

5 Main Facts:
- The continuity of cell is based on the reproduction o
f cells.
- The reproduction of an ensemble as complex as a cell can not occur by a mere pinching in half; a cell is not like a soap bubble that simply enlarges and splits into two.
- The cell division process is an integral part of the cell cycle, the life of a cell from the time it is first formed from a dividing parent cell until its own division into two cells.
- A particular human cell might undergo one division in 24 hours.
- Mitosis is conventionally broken down into five stages: prophase, prometaphase, metaphase, anaphase, and telophase.

Diagram

This is the interphase stage of mitotic division. A nuclear envelop bounds the nucleus which contains one or more nucleoli. Two centrosomes formed by replication of a single centrosome. In an animal cells, each centrosome features two centrioles. Chromosomes duplicated during S phase and can not be seen individually because they have not yet condensed.

Summary
The ability of organisms to reproduce their own kind is the one characteristic that best distinguishes living things from nonliving matter. This unique capacity to procreate, like all biological functions, has a cellular basis. Every cell from a cell. The continuity of life is based on the reproduction of cells, or cell division.
The replication and distribution of so much DNA is manageable because the DNA molecules are packaged into chromosomes, so named because they take up certain dyes used in microscopy.

Video:

10 Key Terms:
- Somatic cell: any cell in a multi cellular organism except a sperm or egg.
- Gamates: a haploid reproductive cell, such as an egg or sperm.
- Sister chromatid : either of two copies of a duplicated chromosome attached to each other by proteins at the centromere and , sometimes, along the arms.
- Centromere: the specialized region of the chromosome where two sister chromatids are most closely attached.
- Centrosome: structure present in the cytoplasm of animal cells, important during cell division; functions as a microtubule.
- Cytokenesis: the division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I or II.
- Interphase: the period in the cell cycle when the cell is not dividing.
- Metaphase: The third of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate.
- Anaphase: the fourth stage mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell.
- Prophase: the first stage of mitosis, in which the chromatin condenses, the mitotic spindle begins to form, and the nucleolus disappears, but the nucleus remains intact.

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