Chromosomes and Mitosis

• What do the cells in our bodies contain?

  The cells in our bodies contain a nucleus which holds genetic material in the form of chromosomes.
• What are chromosomes?

  Chromosomes are coiled-up lengths of DNA molecules.
• What do chromosomes carry?

  Chromosomes carry a large number of genes. These genes are what control the development of different characteristics.
• Body cells have two copies of each chromosomes, one from each parent. There are 23 pairs of chromosomes in a human cell.
• How do chromosomes contribute to cell division?


  They play a crucial role in ensuring accurate distribution of genetic material during cell division.
• What is the diploid number of chromosomes in human cells?

  The diploid number is 46 chromosomes, arranged in 23 pairs.
• What are the two types of chromosomes in humans?

  Autosomes and sex chromosomes.
• How many pairs of autosomes do humans have?

  22 pairs of autosomes.
• What type of cells typically contain 46 chromosomes?

  Somatic cells (body cells).
• What are gametes?

  Reproductive cells that contain 23 single chromosomes (haploid).
• Why do gametes have only 23 chromosomes?


  To ensure that when they combine during fertilization, the resulting zygote has 46 chromosomes.
• Why do red blood cells lack chromosomes?

  They lose their nucleus during development to maximize space for hemoglobin.
• What is aneuploidy?


  A condition where cells have abnormal numbers of chromosomes, often seen in cancer cells.
• What is the cell cycle?

  The cell cycle is where body cells in multi-cellular organisms divide to produce new cells.
• What part of the cell cycle is mitosis?

  Mitosis is where the cell divides.
• What do multicellular organisms use mitosis to do?

  They use mitosis to grow or replace cells that have been damaged.
• Growth and DNA Replication:

  • In a cell that's not dividing, the DNA is spread out in long strings.
  • Before division, the cell has to grow and increase the amount of its sub-cellular structures - mitochondria, ribosomes...
  • After increasing the number of sub-cellular structures, the cell then duplicates its DNA - so there's one copy for each new cell.
  • The DNA copied forms x-shaped chromosomes.
• What are the primary functions of the cell cycle?


  Cell growth, DNA replication, and cell division.
• Why is the cell cycle important for multicellular organisms?


  It is essential for growth, development, and the replacement of worn-out cells.
• What percentage of the cell cycle does interphase occupy?


  Interphase occupies about 90% of the cell cycle.
• During which stage of interphase does DNA replication occur?


  DNA replication occurs during the S phase.
• What does the cell cycle do?

  The cell cycle makes new cells for growth, development, and repair
• If you burn your skin, in order to replace the damaged cells, the surrounding cells undergo mitosis.
• Mitosis is the the stage of the cell cycle where the cell divides
• What happens before mitosis?

  Growth and DNA Replication
• What happens during growth and DNA replication?

  1. When a cell isn't dividing, it's DNA is stored in long strips.
  2. Before division, a cell must increase its amount of sub-cellular structures.
  3. Then, DNA is duplicated, creating one copy for each new cell. The copied DNA forms x-shaped chromosomes.
• What's formed after growth and DNA replication?

  Two exact copies of duplicated x-shaped chromosomes
• When does mitosis occurr?

  After the cells DNA has been duplicated
• What are the steps of mitosis?

  1. Chromosomes line up at centre of the cell and cell fibres pull them apart. The two arms of each x-shaped chromosome is pulled to opposite ends of the cell.
  2. Membranes form around each of the sets of chromosomes, becoming the nuclei of the two new cells.
  3. Cytoplasm and cell membrane divide, forming two, genetically identical daughter cells
• Name the steps of growth + DNA repication and mitosis

  1. In a cell that's not dividing, DNA is stored in long strings
  2. Cell increases amount of sub-cellular structures
  3. DNA is duplicated, one copy for each new cell as x-shaped chromosomes
  4. Chromosomes line up along cell equator, then eahc arm of chromosome pulled to opposite ends of cell
  5. Membranes form around each set of chromosomes - creating nuclei of new cells
  6. Cell membrane and cytoplasm divide
• How can you tell wether a cell is undergoing mitosis?

  You can see the x-shaped chromosomes in the middle of the cells / you can see the arms of the chromosomes being pulled apart