mitosis

• What requires a continuous supply of new cells in multicellular eukaryotic organisms?

  Growth, development, and repair
• Why do young organisms particularly need a continuous supply of new cells?

  To grow in size
• Why do older organisms need to constantly replace lost cells?

  For repair and replacement of damaged tissues
• What is the name of the process through which cells are generated?

  The cell cycle
• What can the cell cycle be thought of as?

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

  Growth, DNA replication, mitosis and division
• During the first step of the cell cycle, what happens to the cell?

  It grows in size
• During cell growth, what happens to the number of subcellular structures?

  The number increases
• What subcellular structures increase in number during cell growth?

  Mitochondria and ribosomes
• What is the purpose of DNA duplication in the cell cycle?

  So each new cell has a full set
• What happens to DNA when a cell is not dividing?

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

  It condenses into chromosomes
• What are chromosomes described as?

  Crude packets of DNA
• What do the genes within the DNA of each chromosome control?

  Development of different characteristics
• How many copies of each chromosome do eukaryotic cells typically have?

  Two copies
• What is each pair of chromosomes called?

  A pair
• Where does each copy of a chromosome come from?

  One from mother, one from father
• How many pairs of chromosomes do humans have?

  23 pairs
• What is the total number of chromosomes in a human cell?

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

  They have different numbers of chromosomes
• What happens to each of the 46 chromosomes as the cell prepares for division?

  Each is duplicated
• What shape do the duplicated chromosomes form?

  An X shape
• Why does the video color each half of the chromosome green?

  To show the halves are duplicates
• What is each half of the X-shaped chromosome sometimes referred to as?

  An arm
• What is true of the DNA on the right arm compared to the left arm of a chromosome?

  It is the same
• Where do the 46 chromosomes line up when the cell is ready to divide?

  Along the center of the cell
• What attaches to each half of the chromosome during cell division?

  Fibers from either side of the cell
• What do the cell fibers do to the chromosomes?

  Pull the arms to opposite sides
• What happens to the X-shaped chromosomes when the cell fibers pull them apart?

  They break in half into two arms
• What is the result of the cell fibers pulling the chromosomes apart?

  Genetic material divides among the two sides
• What is the third and final stage of cell division called?

  Division or cytokinesis
• What happens to the cell membrane and cytoplasm during cytokinesis?

  They pull apart
• What is formed during cytokinesis?

  Two daughter cells
• What is the chromosome composition of the resulting daughter cells?

  Half in each cell
• How does the DNA of the daughter cells compare to each other and the parent cell?

  They are identical
• What can the resulting daughter cells contribute to?

  Growth, development, or repair
• What process do the resulting daughter cells undergo?

  The cell cycle all over again