All cells arise from other cells

• What is the cell cycle?

  the process by which a cell grows, prepares for division, and divides to form two new cells.
• Name the stages of the cell cycle

  Interphase (G1, S, G2):

  Gap 1 phase - cell grows, making proteins and organelles

  Synthesis phase - DNA replication occurs (each chromosome duplicates into two sister chromatids).

  Gap 2 phase - More growth, organelles prepare for division.
• Tip: DNA replication happens in S-phase, NOT mitosis!
• What is mitosis

  Mitosis is a type of cell division that produces two identical daughter cells (used for growth and repair).
• Name the stages of mitosis

  Prophase

  metaphase

  anaphase

  telophase
• What happens in prophase?

  
  

  During prophase, chromatin condenses into chromosomes, which are made up of two identical sister chromatids, joined together at the centromere. 

  
  

  the nuclear envelope breaks down, and the centrosomes move towards opposite ends of the cell.
• what happens in metaphase?

  Chromosomes line up at the cell equator and spindle fibres attach to each side of the centromere
• what happens in anaphase?

  Sister chromatids separate and move to opposite poles.
• what happens in telophase?

  Nuclear envelopes reform, chromosomes decondense. cytokinesis splits the cytoplasm, forming two identical daughter cells.
• tip: Meiosis creates genetic variation due to crossing over & independent assortment, while mitosis produces clones.
• What can uncontrolled mitosis lead to?

  Cancer and tumors
• What do treatments to uncontrolled cell division aim to target?

  Rate of cell division
• How does cancer occur?

  Cancer occurs when cells divide uncontrollably due to mutations in genes that control the cell cycle
• How do Prokaryotic cells divide?

  Binary fission
• Is binary fission asexual or sexual reproduction?

  Asexual
• Explain binary fission

  DNA & plasmids replicate – The circular DNA replicates once, while plasmids may replicate multiple times.

  The cytoplasm expands, and the two copies of DNA move to opposite poles.

  Cytoplasm begins to divide – A new cell wall starts forming.

  Two daughter cells form – Each has one copy of the circular DNA but can have different numbers of plasmids.
• WHats faster, binary fission or mitosis?

  Binary fission
• How do viruses replicate?

  Use host cells and replicate virus particles
• What happens in the cell cycle?

  In the first phase, the cell grows and makes copies of its DNA and organelles.

  In the second phase, the nucleus divides into 2

  And in the third phase, the cell divides in two
• During interphase, the chromatin doesn’t form chromosomes. Instead, it looks unfolded. 
• The mass of a cell doubles during interphase. Suggest why.

  During interphase, a cell grows and makes copies of each organelle in preparation for cell division. This doubles the mass of the cell during interphase.