Mitosis Flashcards
Why are chromosomes always in pairs?
Because one of them is derived from the male parent and the other from the female parent.
What do chromosomes carry?
DNA.
What does the DNA in the chromosomes carry?
Genes.
What does the genes control?
The activities of the cell, they type of cell it becomes, the species of the organism and the individual characteristics of the organism.
What are chromatids?
Before cell division the chromosomes replicate and each chromosome has made a copy of itself. The copies and the originals are now called chromatids.
What is a centromere?
The special region of a chromatids where is it held together.
How many chromosomes are in a human cell?
23
What are the 7 steps of cell division involving chromosomes?
- Each chromosome has replicated to form chromatids.
- The nuclear membrane disappears. Fibers appear in the cytoplasm and foram a spindle. The chromosomes move to the equator of the spindle.
- The spindle fibers shorten and appear to pull the chromatids apart by their centromeres.
- Chromatids are now chromosmes. The chromosomes migrate to opposite ends of the cell as the spindle fibers shorten.
- The cell begins to divide.
- The nuclear membrane forms again. The cell contracts. The chromosomes become less distinct.
- Two cells formed. Chromosomes revert back to original shape and eventually cannot be seen. Each cell has a full set of chromosomes identical to the parent cell.
What is the process of cell division that produces cells containing identical sets and numbers of chromosomes?
Mitosis.
What does mitosis ensure?
That every cell of an organism carries an identical set of genes.
If every cell carries the same set of genes, how do cells become specialized in shape and function to do different jobs?
The genes which are not relevant to the cell’s function are not activated.
