ZOOLAB: The Cell Cycle

• Interphase: The longest stage of the cell cycle, comprises three phases: G1 (Growth Phase 1), S phase (Synthesis Phase), and G2 (Growth Phase 2)
• G1: Cell increases in size, undergoes metabolic pathways - accumulates biomolecules and energy and the cell duplicates organelles.
• The S-Phase: DNA material is replicated, protein synthesis of histones.
• G2: Cell produces more ATP, more organelles are produced, growth is still evident.
• The Mitotic Phase: Cell division happens
• G0: The cell is not involved in cell division. This could be temporarily or permanently.
• G2 Checkpoint: Checks for cell size, dna damage, dna replication
• G1 Checkpoint: Checks for cell size, nutrients, growth factors, and dna damage.
• Spindle Assembly Checkpoint: checks for chromosome attachment to spindle.
• Cells that are highly specialized and lack the ability to divide:

  • Nerve Cells
  • Muscle Cells
  • Erythrocytes
• Cells that do not normally divide but can be induced when given the right stimulus:

  • Liver Cells
  • Lymphocytes
• Cells that possess a high level of mitotic activity:

  • Epithelial Cells
• Prophase: Nuclear envelop disintegrates, chromatin to chromosomes, centrioles travel to opposite poles, spindle fibers form
• What phase of cell division is being shown?

  Prophase

  
• Metaphase


  Nuclear envelop disintegrated, centrioles are in the opposite poles, chromosomes lined up in the center, spindle fibers attached to sister chromatids.
• What phase of cell division is being shown?

  Metaphase

  
• Anaphase: Sister chromatids separate from the centromere, cells become elongated.
• Anaphase


  What phase of cell division is this photo showing?

  
• Telophase: Sister chromatids reach the opposite poles, chromatid to chromatin, nuclear membrane starts to form, and spindle fibers disintegrate.

  reach
• What phase of cell division is this?

  Telophase

  
• Cytokinesis: formation of two daughter cells.
• Animal Cell: separate from the cleavage furrow.
• Plant Cell: Forms a cell plate on the metaphase plate
• What type of cell is undergoing this type of cytokinesis?

  Animal Cell

  
• What type of cell is undergoing this type of cytokinesis?

  Plant Cell

  
• Meiosis: Has two rounds of divisions, daughter cells are haploid, promotes variation
• Prophase 1

  • Nuclear envelop disintegrates, chromatin to chromosomes, centrioles travel to opposite poles, spindle fibers form
  • Synapsis occurs, exchange of chromosomal segments happen (crossing over)
• Metaphase 1: Nuclear envelop disintegrated, centrioles are in the opposite poles, homologous chromosomes lined up randomly in the center, spindle fibers attached to each chromosome
• Anaphase 1: tetrads/homologous chromosomes separate from the chiasmata, cell become elongated.
• Telophase 1 & Cytokinesis: Chromosomes reached the opposite poles, chromosomes may decondensed, nuclear membrane may start to form, two haploid cells formed.
• Interkinesis: period of cell growth, no dna replication
• Telophase II & Cytokinesis: Sister chromatids reached the opposite poles, chromatid to chromatin, nuclear membrane starts to form, four unique haploid cells formed.
• Maturation Promotion Factor: Soluble factor which induces mitotic division or maturation
• Active MPF stimulates: Nuclear envelope breakdown, chromosome condensation, mitotic spindle formation, targeted protein degradation.
• Apoptosis: cell death
• Failed separation of homologous chromosomes/sister chromatids leads to genetic disorder