CELL QUESTION 1987:				L. PETERSON/AP BIOLOGY 
	Discuss the process of cell division in animals. Include a description of
	mitosis and cytokinesis, and of the other phases of the cell cyle.
	Do not include meiosis.


  STANDARDS:
  PART I.  DESCRIPTION OF MITOSIS IN ANIMAL CELLS:          Max. = 7 points
  General
  __  division of nucleus
  __  daughter cells acquire the same number and kinds of chromosomes as 
         in the mother cell
  __  process for growth or repair or asexual reproduction
  __  list phases in correct order (P,M,A.T)
  Prophase (one point each / max. 2)
  __  centrioles move apart
  __  chromosomes condense
  __  nucleolus is no longer visible
  __  nuclear envelope disappears
  __  asters and spindle form
  Metaphase
  __  sister chromatids (chromosomes) are in a line at the midpoint of the spindle
  Anaphase (one point each / max. 2)
  __  centromeres uncouple (split)
  __  chromosomes move to opposite poles
  __  microtubules involved in the push/pull movement
  Telophase (one point each / max. 2)
  __  reverse of prophase
  __  nuclear envelope reforms
  __  nucleolus reappears
  __  chromosomes become diffuse
  __  spindle and aster disappear
  __  centrioles are replicated
  Points less frequently mentioned:
  __  function of centrioles
  __  definition of kinetochores
  __  description of polar microtubules and kinetochore microtubules
  __  definition of chromatids
  *In order to obtain a score of 10, there must be points in all three sections.
    If only two sections are written the maximum is 9. 
  PART II.  CYTOKINESIS:
  __  division of cytoplasm
  __  formation of a cleavage furrow
  __  occurrence of cytokinesis in the cell cycle
  Points less frequently mentioned:
  __  function of cytokinesis
  __  dense belt of actin and myosin microfilaments
  __  purse-string mechanism
  __  furrow occurs at location of equatorial plane
  __  cytochalasin blocks activity of microfilaments (stops cytokinesis)
  
  
  PART III.  OTHER PHASES OF THE CELL CYCLE (INTERPHASE):
  General
  __  list G1, S, and G2 in correct order
  __  G1, S, and G2 are part of interphase
  __  chromosomes appear as a mass of chromatin material
  G1
  __  synthesis of cell organelles or cell doubles in size
  __  restriction (decision) point or point of no return
  S
  __  synthesis or replication of DNA or DNA replication occurs during interphase
  G2
  __  synthesis of microtubular assembly, or prepare for mitosis
  Points less frequently mentioned:
  __  description of nucleosomes
  __  times in each phase
  __  growth factors
  __  some cells do not go beyond G1
  __  after cell passes "S", mitosis will usually continue
  __  colchicine prevents the formation of microtubules