Cell Cycle (Mitosis & Meiosis)

1. Describe cell cycle.

The cell cycle is the orderly sequence of events that occurs from the time a cell divides to form two daughter cells to the time those daughter cells divide again. The phases of the cell cycle occur in meiosis as well as mitosis.

2. What is nuclear division?

In nuclear division also known as, Karyokinesis, the nucleus divides during this process. Nuclear division includes several subphases. Prophase, Metaphase, Anaphase, and Telophase.

3. What is interphase?

During interphase the cell is growing and metabolic activity is very high. Toward the end of interphase, new DNA is synthesized and the chromosomes are replicated. Each chromosome of the homologous pair is then composed of two sister chromatids.

4. Cytokenises is the process in which the cytoplasm divides and two identical daughter cells are formed.

5. Homologous chromosomes: In diploid (2n) organisms, the genome is composed of homologous chromosomes. One chromosome of each homologous pair comes from the mother (called a maternal chromosome) and one comes from the father (paternal chromsosome).

6. Phases of mitosis:

Prophase, Interphase, Anaphase, Metaphase, and Telophase.

7. Phases of meiosis and how different from mitosis.

Prophase, Metaphase, Anaphase, and Telophase.

Meiosis follows phases similar to those in mitosis, but the outcome of the process is very different. The DNA of the parent cells is replicated in interphase preceding both mitosis and meiosis. However, in meiosis, replication is followed by two divisions.

Meiosis reduces the chromosome number of the parent cell so that four daughter cells are produced, each with one-half the chromosome number of the parent cell. Each daughter cell contains only one chromosome from each homologous pair.

8. Describe the process and purpose of crossing over.

Crossing over occurs during prophase I of meiosis. In prophase I of meiosis, the replicated homologous pair of chromosomes comes together in the process called synapsis, and sections of the chromosomes are exchanged. You can see that after crossing over, the resultant chromosomes are neither entirely maternal nor entirely paternal, but contain genes from both parents. Synapsis and crossing over occur only in meiosis