Chapter 9 Section 2

Main Idea Eukaryotic cells reproduce by mitosis, the process of nuclear division, and cytokinesis, the process of cytoplasm division.

Mitosis The key activity of mitosis is the accurate separation of the cell’s replicated DNA In multi-cellular organisms, this process of mitosis increases the number of cells as a young organism grows to its adult size

Stages of Mitosis Prophase The longest phase Chromosomes are shaped like an X Sister chromatids are structures that contain identical copies of DNA The structure at the center of the chromosome where the sister chromatids attached is called the centromere

Metaphase Chromosomes are moved to the middle of the cell Chromosomes align Movement of chromosomes is due to the action of spindle which is made of microtubules. Centrosomes are now at the opposite poles

Anaphase This is usually the shortest phase of mitosis 2 sister chromatids split The chromatids, now chromosomes move towards opposite poles Each pole of the cell has a complete, identical set of chromosomes

Telophase Nuclear membrane begins to re-form Chromosomes start to elongate to form chromatin Nucleoli reappear Cell is elongated and ready for cytokinesis

Cytokinesis Cytokinesis in animal cells involves an inward pinching of the fluid plasma membrane to form cleavage furrows Plant cells have a firm cell wall, therefore they form a cell plate

Growth of organisms, development of embryos, tissue repair, and asexual reproduction all involves mitosis Mitosis does not happen by itself. It is a part of the cell cycle