4.5.1 Cell division produces cells needed for growth, maintained and reproduction

Mitosis: 有丝分裂

Amitosis: 无丝分裂

Meiosis: 减数分裂

Binary fission: 二分裂，具体过程不考

• All DNA in a cell is called the cell’s genome 基因组
• A genome can consist of a single DNA (common in P cells) or a number of DNA molecule (common in E cells)
• Somatic cells have 2 sets of chromosomes, and they are non-productive
• Gametes have a chromosome number which is half of the somatic cells, and they are productive

4.5.2 Phases

$G_1$ phase: Metabolic activity and growth

$S$ phase: Metabolic activity, growth and DNA synthesis

$G_2$ phase: Metabolic activity, growth and preparation for cell division

4.5.3 Mitotic cell division

It includes 5 steps: Prophase Pro-metaphase Metaphase Anaphase Telophase

1. Prophase: chromatin condenses into chromasomes