cell cycle

• Why do multicellular eukaryotic organisms need new cells?

  For growth, development, and repair
• What is the process called through which cells are generated?

  The cell cycle
• What are the three main stages of the cell cycle?

  Growth, DNA replication, and mitosis
• What happens during the first step of the cell cycle?

  The cell grows and increases subcellular structures
• What occurs during DNA replication in the cell cycle?

  The DNA is duplicated for new cells
• How does DNA appear when a cell is not dividing?

  It is spread out in long strings
• What happens to DNA as a cell prepares for division?

  It condenses into chromosomes
• What do chromosomes contain?

  A large number of genes
• How many copies of each chromosome do eukaryotic cells have?

  Two copies, one from each parent
• How many pairs of chromosomes do humans have?

  23 pairs
• What shape do duplicated chromosomes take?

  An X shape
• Why can't animals of different species reproduce fertile offspring?

  They have different numbers of chromosomes
• What is the significance of the right and left arms of a chromosome?

  They are duplicates of each other
• What happens to chromosomes during cell division?

  They line up along the center of the cell
• What attaches to the chromosomes during division?

  Fibers from either side of the cell
• What do the fibers do during chromosome separation?

  They pull the arms to opposite sides
• What is the final stage of the cell cycle called?

  Cytokinesis
• What occurs during cytokinesis?

  The cell membrane and cytoplasm pull apart
• What do the resulting daughter cells contribute to?

  Growth, development, or repair
• What happens to the daughter cells after division?

  They undergo the cell cycle again