Eukaryotic Cell Cycle

INTRODUCTION

To divide, a cell must grow, replicate its genetic material (DNA), and split into two daughter cells. Cells perform these tasks in an organized series of steps that make up the cell cycle. In eukaryotic cells, or cells with a nucleus, the stages of the cell cycle are divided into two major phases: interphase and the mitotic (M) phase.

• During interphase, the cell grows and makes a copy of its DNA.

• The mitotic (M) phase, divides the cell DNA into two sets and its cytoplasm, forming two new cells.

INTERPHASE

A cell forms, by division of its mother cell. The preparation for division happens in three steps:

• G1 phase- During G1 also called the first gap phase, the cell grows physically larger, copies organelles, and makes the

• The chromosomes begin to decondense and return to their string formation.

• Cytokinesis, the division of the cytoplasm to form two new cells.

• When cytokinesis finishes, we get two new cells, each with a complete set of chromosomes identical to those of the mother cell. The daughter cells can now begin their own cellular lives and undergo mitosis themselves, repeating the cycle.

Meiosis, on the other hand, is used for just one purpose in the human body: the production of gametes—sex cells, or sperm and eggs. It makes daughter cells with exactly half as many chromosomes. Meiosis in humans is a division process that makes a diploid cell (one with two sets of chromosomes) to haploid cells (ones with a single set of chromosomes).

PHASES OF MEIOSIS

In meiosis, the cell needs to separate sister chromatids. But it must also separate homologous chromosomes, the similar but non-identical chromosome pairs an organism receives from its two parents.

Homologue pairs separate during meiosis I. Sister chromatids separate meiosis II.

Since cell division occurs twice during meiosis, one starting cell can produce four gametes (eggs or sperm). In each round of division, cells go through four stages: prophase, metaphase, anaphase, and