1. Cell Division and Growth:
We are constantly changing; cells in our bodies grow, divide, and die constantly.
They do this a different rates and times. Some cells mature quickly and die quickly,
while others mature slowly and die slowly.
Cell division there is two types of cell division. Mitosis and Meiosis
Mitosis is the type of division that your body cells go through.
Meiosis only occurs with the sex cells.
The cell cycle: Most of the life cycle of a eukaryotic cell is spent in a period of growth
and development called interphase.
Interphase: during this phase the cell grows, makes a copy of its hereditary
material (DNA) and prepares for cell division. The cell matures in this phase until mitosis
begins.
This phase of the cells life is the growing up stage, the cell matures and then reproduces.
All cells come from existing cells and when a cell reproduces, it makes two exact copies
of itself to replace it. Cells do this through a process called mitosis.
Mitosis
Cells divide in steps, the nucleus of the cell divides, and then the cytoplasm
divides. Each new nucleus is identical to the original nucleus.
The steps are called prophase, metaphase, anaphase, and telophase
Interphase: the cell’s chromosomes duplicate. The nucleolus is visible in the nucleus.
Prophase: The chromatid pairs are now visible and the spindle fibers begin to
form.
Metaphase: the chromatid pairs line up in the center of the cell.
Anaphase: the chromosomes pairs separate
Telophase: the chromosomes move to opposite ends of the dividing cell and the
cytoplasm divides.
The two new cells then move back into interphase and begin the cycle over.
Mitosis is how our bodies repair damage to organs and tissues. When tissue is damaged
the surrounding cells begin going through mitosis to replace the damaged cells. This is
why brain, spinal, and nerve damage is permanent because these cells don’t go through
mitosis to replace damaged cells. This is why a broken bone will heal, but a severed
spinal cord won’t.
Mistakes in mitosis also can result in mutations, causing different things such as disease
(cancer) and abnormal growth; this can include moles and non-cancerous tumors.