cells and control

• Mitosis


  1. Cell division

  2. Growth and repair
• Interphase


  1. Cell replicates DNA

  2. Cell makes more organelles like mitochondria and ribosomes
• Mitosis


  1. Prophase: Nucleus breaks down, spindle fibers appear

  2. Metaphase: Spindle fibers pull chromosomes to middle

  3. Anaphase: Spindle fibers pull chromatids to each end

  4. Telophase: Nucleus reforms

  5. Cytokinesis: Cytoplasm splits, creating two daughter cells
• Mitosis always produces identical cells
• Mistakes in DNA copying during mitosis

  Can cause uncontrolled cell division and tumors
• Growth


  Increase in size or number
• Plant cell growth

  Cells elongate and divide at roots
• Animal cell growth


  Cells typically just divide
• Percentile charts


  Measure growth by comparing to other organisms
• Stem cells


  Unspecialized cells that can differentiate into specialized cells
• Types of stem cells

  • Embryonic stem cells
  • Adult stem cells
  • Plant meristem stem cells
• Embryonic stem cells


  • Can turn into any type of specialized cell
• Adult stem cells


  • Can only turn into certain types of specialized cells
• Plant meristem stem cells


  • Can turn into any type of plant cell
• Stem cells can be used in medicine to produce needed cell types, but there are risks of tumor growth or immune rejection
• Nervous system

  System that sends and receives information
• Parts of the nervous system

  • Central nervous system (brain and spinal cord)
  • Peripheral nervous system (all other neurons)
• Types of nerve cells

  • Sensory neurons
  • Motor neurons
  • Relay neurons
• Sensory neurons

  • Connected to receptors, detect stimuli
• Motor neurons

  • Carry impulses to muscles and glands
• Relay neurons

  • Short neurons found in brain and spinal cord
• Myelin sheath


  Insulates neurons and speeds up impulses
• Nerve impulse pathway


  1. Stimulus detected by receptor

  2. Impulse travels through sensory, relay, and motor neurons

  3. Impulse reaches effector (muscle or gland)

  4. Effector responds
• Synapse


  Small gap between neurons where neurotransmitters are released
• Reflex arc


  1. Receptor detects stimulus

  2. Impulse travels directly to effector without going through brain

  3. Effector (muscle) responds quickly