Lecture 95 September 13

E.  Cladistics

      	1.  End result of process is the production of a cladogram.

	2.  Branches represent lineages that show either ancestral or
		derived attributes
      	3.  Whether a characteristic is ancestral or derived is determined
		by many of the same process as with the other two methods.
		In addition, one can assume that if a characteristic is found
		in a wide variety of organisms of an earlier time period, that
		it is the ancestral characteristic.  Also if it is present in
		older fossils but lacking in newer it is ancestral and vice
		versa, present in newer and lacker in older, it is derived.

     	4.  A cladistic approach represent the main thrust of modern
		systematics

I.  The Origin of Life

     A.  Characteristics of living organisms
	1.  Chemical composition-formed of CHON
	2.  Elements are bonded together to produce organic molecules
 		such as amino acids, carbohydrates, lipids and nucleic acids.
	3. In addition to the above, all organisms show:
		a.  consumption of energy
                b.  replication
                c.  response to stimuli
                d.  growth
    	4.  Life is a membrane bound phenomenon, where movement
		of materials into and out the organism is regulated
     B.  Some observations that indicate possible processes important
		in the orgin of life.
        1.  As shown by a variety of experiments, organic molecules can be
		produced without involving living things.
        2.  Water because it is a dipole has some unique attributes
	3.  One hypothesis concerning the origin of life is the capture and
		retention of organic materisls by membrane bound spherules.