CHROMOSOMES What is a chromosome made of DNA

CHROMOSOMES

What is a chromosome? made of DNA consists of many genes.

Human body cells have 46 chromosomes.

Condensed chromosomes supercoiled DNA composed of two exact copies. are shaped like X.

Why do cells divide? To make more cells for: asexual reproduction (produce new individuals) growth and development (from zygote to adult) repair (replace cells destroy by injury) replacement (replace cells that have died)

Interphase The cell carries out its normal functions. The cell grows.

Interphase Before a cell can divide, it must duplicate its DNA duplicates

MITOSIS There are four phases in mitosis: Remember me! 1. prophase 2. metaphase pmat 3. anaphase 4. telophase

Prophase The duplicated chromosomes condense. Each chromosome consists of two identical sister chromatids. pro = chromosomes condensed cell

Metaphase Chromosomes line up along the middle of the cell. meta = middle

Anaphase Chromosomes are pulled apart and move to opposite ends of the cell. Ana = Apart

Telophase The chromosomes gather at opposite poles of the cell forming two nuclei. telo = two nuclei

Cytokinesis The cytoplasm divides, forming two identical cells. The cells can now go about their business.

Recap…. . Mitosis is Division of the nucleus 46 46 46 one cell two identical cells

metaphase

anaphase

interphase

telophase

prophase

cytokinesis

cytokinesis