topic 2- Cells and Control

• Why do multicellular eukaryotic organisms need new cells?

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

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

  They have different numbers of chromosomes
• What shape do duplicated chromosomes form?

  An X shape
• 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 cell division?

  They pull the arms of the chromosomes apart
• What is the final stage of the cell cycle called?

  Cytokinesis
• What happens during cytokinesis?

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

  Growth, development, or repair
• What can daughter cells do after division?

  Undergo the cell cycle again
• What are specialized cells?

  Cells that perform specific functions
• What is the process by which cells become specialized?

  Differentiation
• What types of organisms have specialized cells?

  • Animals (e.g., humans)
  • Plants (e.g., P plants)
• How many types of specialized cells are there approximately in humans?

  Around 200 types
• What is the role of a sperm cell?

  To deliver genetic material to an egg cell
• Why does a sperm cell have half the genetic material of a normal adult cell?

  To combine with the egg's genetic material
• What adaptation helps a sperm cell swim?

  The flagellum acts like a tail
• Why is the shape of a sperm cell streamlined?

  To aid in swimming through fluids
• What is the function of mitochondria in sperm cells?

  To provide energy for swimming
• What do sperm cells have at their front to aid fertilization?

  Digestive enzymes to penetrate the egg
• What are the general characteristics of specialized cells?

  • Specific roles in the body
  • Unique shapes and structures
  • Different organelle compositions
• What is differentiation in the context of cells?

  The process by which cells become specialized
• What is a zygote?

  A fertilized egg cell
• What happens to a zygote during development?

  It divides by mitosis into multiple cells
• What occurs after the initial cell divisions of a zygote?

  The cells are identical and not specialized
• What is the significance of differentiation?

  It allows cells to perform specific functions
• What are stem cells?

  Cells that can divide and differentiate
• What is the role of stem cells in development?

  • Ability to divide by mitosis
  • Can differentiate into specialized cells
• How do specialized cells differ from each other?

  They have different shapes and structures
• What is the relationship between structure and function in specialized cells?

  Structure is adapted to fulfill specific functions