Cell division

• G1 phase - Cells grow and prepare to divide by making proteins needed for DNA replication and cell division
• What are the two phases of the cell cycle ?

  Interphase and mitotic phase.
• What happens during interphase?

  During interphase, the cell grows, replicates its DNA, and prepares for cell division. Mitochondria and chloroplasts grow and divide to increase numbers in the cytoplasm. Protein synthesis occurs in the cytoplasm
• What 3 stages happens in interphase?

  1. G1
  2. S
  3. G2
• What happens in G1 of interphase?

  First growth stage. Proteins synthesises. Organells are replicated and the cell increases in size to prepare for division
• What happens in the S phase?

  Dna is replicated in the nucleus
• What happens in the G2 stage of interphase?

  Cell continues to increase in size. Energy stores increase. Dna is replicated and checked for errors
• What are the two phases of mitosis phase in the cell cycle?

  Mitosis and Cytokinesis
• What is cytokenisis?

  The division of the cytoplasm during cell division.
• What are checkpoints in the cell cycle?

  Control mechanisms where processes at each stage are monitored to check for errors and accurate completion before cell can progress onto the next stage
• Where are the checkpoints in the cell cycle?

  1. End of G1 phase before S phase
  2. End of G2 before mitotic phase
  3. Metaphase checkpoint- spindle fibre assembly point
• What are the phases of mitosis?

  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
• What is a centromere?

  Structure on chromosomes that link sister chromatids together. Attached to spindle fibres during DNA movement
• What is a centriole?

  Organelle that makes spindle fibres in the cell
• What are homologous chromosomes?

  Homologous chromosomes are pairs of chromosomes that have the same genes in the same structure, but may have different versions of those genes eg one from mother and one from the father
• How is variation in meiosis explained?

  Crossing over of alleles in prophase 1 and independent assortment of chromosomes during meiosis lead to genetic variation.
• What happens during telophase?

  During telophase, the nuclear membrane reforms around the separated chromosomes, the spindle fibers disappear, and the cell begins to divide into two daughter cells.
• What does the G1 checkpoint in the cell cycle check for?

  1. Cell size
  2. Cell damage
  3. Differentiated cell (can’t replicate)
  4. Senescent cells (reached number of maximum division)
• What stage is the spindle fibre checkpoint in the cell cycle ?

  Metaphase
• What is a totipotent cell?

  A totipotent cell is a cell that has the ability to differentiate into any type of cell in the body, as well as extraembryonic cells.
• What is a multi potent cell?

  A multipotent cell is a type of stem cell that has the ability to differentiate into multiple, but limited, cell types in a certain type of tissue
• What are the specialised features of the squamous epithelium ?

  Very thin ( 1cm thick) to shorten diffusion pathway. Increases rate of diffusion of oxygen into the blood. Lines lungs
• What are the specialised features of the neutrphils ?

  Has many lysosomes which contain enzymes, killing pathogens. Has a multi lobed nucleus