DNA, Chromosomes, and Cell Division

DNA and Chromosomes

• DNA

• Chromosome: X-shaped structures found in the nucleus of dividing cells.

  • A chromosome is made of two identical sister chromatids.

  • Chromosomes are made of DNA wrapped around proteins.

  • Chromosomes location: nucleus of the cell.

  • Sister chromatids are held together by a centromere.

• Diploid: Body cells that contain the full number of chromosomes (46 in humans).

• Haploid: Sex cells that contain only half the number of chromosomes.

Cell Cycle Stages

• S phase: The cell is copying DNA and performing cell functions.

• Metaphase: Chromosomes line up along the equator.

• Anaphase: Chromatids separate and move to opposite sides.

• Prophase: DNA condenses and forms chromosomes.

• Telophase: The nuclear membrane forms in each new cell.

Mitosis Structures

• Spindle: Structure that moves individual chromosomes during mitosis.

• Centrioles: A pair of structures that anchors the spindle.

Cell Division Processes

• Mitosis: The process by which the nucleus divides into two new nuclei.

• Cytokinesis: The process by which the cell splits into two new daughter cells.