Cell Cycle

• Cell division and its control mechanism are important aspects of cell biology.
• Crossing over between strands of DNA ensures genetic diversity
• Mitosis is a type of cell division that is involved in all cell proliferation and during asexual reproduction.
• Meiosis is a type of cell division that involves the division of cell nuclei into two, each containing a complete set of chromosomes, and is involved in asexual reproduction.
• The cell cycle is the process of growth and division of cells, and is carefully controlled to prevent the development of cancer cells.
• Mammalian cells take approximately 24 hours to go through the cell cycle.
• The phases of the cell cycle include G1, S, G2, M, and G0.
• The cell cycle is controlled by molecules named cyclin dependent kinases (CDKs), which enable the cells to pass through checkpoints.
• Injection studies in frog oocytes showed that “maturation promoting factor” (MPF) can induce M phase in G2 nuclei.
• Cyclin-CDK complexes, such as the one discovered in frogs eggs, play a role in triggering the cells' passage past the G2 checkpoint into the M phase.
• DNA replication, DNA mass per nucleus (Au), occurs in all multicellular organisms, including the root tip of a plant.
• Cytokinesis is the process where the cell membrane divides, separating the cytoplasm into two daughter cells.
• Mitosis is the process where cell nuclei divide into two, each containing a complete set of chromosomes, producing new cells that are genetically identical to the parent cell.
• Meiosis is the process where cell nuclei divide into two, each containing a complete set of chromosomes, and is involved in asexual reproduction.
• The cell cycle is carefully controlled to prevent the development of cancer cells.
• Mammalian cells take approximately 24 hours to go through the cell cycle.
• The phases of the cell cycle include G1, S, G2, M, and G0.
• The cell cycle is controlled by molecules named cyclin dependent kinases (CDKs), which enable the cells to pass through checkpoints.
• Injection studies in frog oocytes showed that “maturation promoting factor” (MPF) can induce M phase in G2 nuclei.
• Cyclin-CDK complexes, such as the one discovered in frogs eggs, play a role in triggering the cells' passage past the G2 checkpoint into the M phase.
• DNA replication, DNA mass per nucleus (Au), occurs in all multicellular organisms, including the root tip of a plant.
• Cytokinesis is the process where the cell membrane divides, separating the cytoplasm into two daughter cells.
• Anaphase is the phase where the paired chromosomes separate and move to opposite sides of the cell.
• Chromosomes dragged apart at 1 µm min−1 during anaphase.
• Telophase is the phase where chromatids arrive at opposite poles of the cell, and new membranes form around the daughter nuclei.
• The chromosomes disperse and are no longer visible under the light microscope during telophase.
• Cytokinesis is the division of the rest of the cytoplasm, which can start after telophase.
• Nuclear envelope reforms around DNA during telophase.
• Chromosomes decondense during telophase.
• In animal cells, cytokinesis results when a fiber ring composed of a protein called actin around the center of the cell contracts, pinching the cell into two daughter cells, each with one nucleus.
• In plant cells, the rigid wall requires that a cell plate is synthesized between the two daughter cells.
• Mitosis generates two diploid (2n) daughter cells, each genetically identical to the parent cell.
• Meiosis is the process undergone by sex cells to form sperm and eggs, these are haploid.
• When cells fuse they return to the diploid state, bringing characteristics together of the mother and father.
• Fusion occurs after pollination in plants or after sex.
• Meiosis has two cell divisions but only one section of DNA replication, these are meiosis i and meiosis ii.
• Meiosis reduces the chromosome number from diploid (2n) to haploid (n).
• In meiosis, prophase i is important as it allows for the exchange of genetic material through crossing over.
• Prophase i in meiosis is different from prophase of mitosis as the two chromosomes combine or synapse to form tetrads.
• Tetrads are also known as bivalents because they contain two pairs of chromosomes.