B2.2 Mitosis

• What do we commonly call the cells produced by mitosis? 

  Daughter cells 
• When a cell divides by mitosis, how many cells are produced? 

  2
• Are the cells created by mitosis genetically identical to each other, or genetically different? 

  Genetically identical 
• How many pairs of chromosomes do most human cells have?

  Human cells have 23 pairs of chromosomes, so 46 chromosomes in total. 
• Steps of the cell cycle:

  • Cellular growth - the cell gets larger and produces more sub-cellular structures, such as mitochondria and ribosomes. 
  • DNA replication - chromosomes duplicate, so that each consists of two arms (copies).
  • More cell growth.
  • Mitosis - the DNA divides into two.
  • Cytokinesis - the cell divides into two
• What is the cell cycle?

  The series of steps that take place as a cell grows and then divides 
• What is the main focus of the video?

  How cells divide and the role of chromosomes
• 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 is the result of the fibers pulling the chromosomes?

  Chromosomes are separated into two arms
• 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
• What should viewers do if they enjoyed the video?

  Like and subscribe
• What is the role of chromosomes in cell division?

  They ensure DNA is accurately distributed
• Why is the cell cycle important for multicellular organisms?

  It allows for growth and tissue repair
• What are subcellular structures?

  Components within a cell
• What is the significance of genes in chromosomes?

  They control the development of traits
• What are homologous chromosomes?

  Chromosome pairs from each parent
• What is the process of chromosome duplication?

  Each chromosome makes a copy of itself
• What is the function of spindle fibers during mitosis?

  They pull chromosomes to opposite sides
• What are daughter cells?

  Cells produced from cell division
• How does the cell cycle relate to organism growth?

  It provides new cells for growth and repair
• Steps of mitosis & cytokinesis:

  • DNA condenses to form chromosomes.
  • Chromosomes line up along the centre of the cells.
  • Cell fibres pull the two arms of each chromosome to opposite sides (poles) of the cell.
  • Cytokinesis - the entire cell divides to form two identical daughter cells.
• Multicellular organisms, like ourselves, require a continuous supply of new cells. 

  What are the three reasons why new cells are required?

  • Growth (we need more cells as we grow)
  • Development (we need new cell types as we develop new tissues)
  • Repair (we need to replace the cells that we lose each day)