STUDY  of   LIFE   (Biology 150 - University of Miami)      

                                                                                                  
 Course is divided into (3) parts:                                                     

    1)     Cellular & Molecular Biology                    

    2)     Cell Reproduction & Genetics                    

    3)     Homeostasis & Physiology                       

                FIRST PART of our study will be...

                             " a Journey thru the COSMOS of the CELL "  

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 Modern Biology is often described as...                             the BIOCHEMISTRY of the CELL

       modern Biology commonly uses a different approach

                                                  than you may used before for studying Biology -

      

       more common approach has been to look at DIVERSITY...

                                          the kinds of plants & animals known to exist -
   
              whole of biology is a counterpoint of two themes:
                      astonishing variety in individual particulars (species);
                      astonishing consistency  in fundamental mechanisms.

   
       Bil 150's current approach to modern biology is to stress...

   

                                              the UNIFYING CONCEPTS of Biology.

   

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In my opinion,

               there are 3 UNIFYING CONCEPTS,                

                which stress the UNITY of LIFE...  
                                                                  [ Campbell describes 10  themes ]

               1.  CELL THEORY

                  2.   EVOLUTION

                       3.    BIOENERGETICS (energy transformation)

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1.    CELL THEORY          (cell doctrine)
1st cells described by R. Hooke in 1663 ( ^ cork cells)  &  Leeuwenhoek 1673                                                            [an essay on Hooke's life work]                     bacteria & spirogyra    in 1670 Marcello Malphigi suggests that plant leaves & stems are composed of cells    by 1805 Lorenz Oken, a German natur-philosopher, claims all organisms consist of cells           but, Cell Theory formally espoused in 1839.....                                 by  Matthais Schleiden (lawyer turned botanist) &                 *                      Theodor Schwann    (animal embryologist)          [met at dinner party in 1837]       in 1858 Rudolph Virchow forcefully states a major paradigm of this new cell theory...        "All cells arise from pre-existing cells"        Thus:  all individuals derived from a single celled organism are related &                          all cells in a multi-celled organism are descended from one fertilized egg.
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     Tenets of the Cell theory  -   Universal Features of Cells on Earth

• all known living things (systems) are composed of cells
• cells arise only from other pre-existing cells (not by Spontaneous Generation)
                         (see experiments of Redi  and  Pasteur* experiments*)
• all energy flow (metabolism & biochemistry) of life occurs within cells
• all living cells on Earth store their hereditary information in DNA molecules - (for use by subsequent generations) - copied by templated polymerization. 

  
    Some important facts about cells (virtual cells  -  Kyrk's Cell Animations^{more later}):
        - their diversity : - many sizes, shapes, & types [165+ in humans]  no two alike ^NAS-6
        - their similarity: - have same basic structural plan
                                   - surrounded by cell membrane
                                   - contain nuclei     (bacteria = genophore = area of DNA)
                                   - similar sub-cell parts (ORGANELLES)
                                   - all contain
     universal properties of all cells*

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 2.  EVOLUTION..."Descent with modification"  
                                      "Nothing in biology makes sense except in the light of evolution"
                                           Theodor Dobzhansky (1973) in Amer. Bio Teacher 35:125-129
     
   Evolution is simply a change in natural/physical characteristics of a population over time
  
    In 1858 Charles Darwin & Alfred Russell Wallace present papers to Linnaean Society
   with 2 important new hypotheses about biological PATTERNS in the natural world.
        ... all species (past & present) are related by descent from common ancestor
        ... hypothesized all species come from preexisting species & they change through time
                -  individuals in a population vary in hereditable traits...(look around class) 
                -  this accounts for the diversity we see in biology... 
                -  living things change gradually over time to become new forms...

                        from one form      ------------------>     to another form

                      (oneSPECIES)     -------->        (New SPECIES)

    Darwin proposed a PROCESS (mechanism) for this (PATTERN) descent & change...

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 MECHANISM - is via NATURAL SELECTION (SURVIVAL of FITTEST)
   
     -  individuals in a population vary in hereditable traits...
 
    -  some traits help individuals survive better or reproduce more.
  
    -  Natural Selection picks those individuals better fit to specific environment...
            only those with superior traits   (physical, behavioral, biochemical) 
            are more likely to SURVIVE and REPRODUCE... 
                                   passing their traits onto their progeny more efficiently
  
    - over time... a whole population's characteristics can change
                                       see an example of natural selection with a predation model*
  
    

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 Examples of SELECTION:  
  Artificial Selection.... examples
       in Cabbage Plants*... 
                   broccoli, cauliflower, Brussels sprouts, cabbage, kale, and
                   collard greens are all derived from Wild Mustard plants
                   horticulturalists SELECT* wild mustards with large buds = Brussels sprouts
  
  Natural Selection.... examples
       case study 1* - Peter & Rosemary Grant & medium ground finch

       case study2   - feeding preferences of different predators does cause changes in guppy
                             populations favoring long-term evolutionary changes by natural selection
                                 David Reznick (UCR) & John Endler (UCSB) - Trinidadian guppies
                                                                                  experimental design and results*    
                                   Student Media - Process of Science: Selection or How environment affects populations*

     UNITY...   Comes from fact that all living things changed,           § a theory
                                           evolved by same rules, the Laws of Evolution          Evolution of Humankind
    

     
3.  BIOENERGETICS - (science of EQUILIBRIUM THERMODYNAMICS)...
             science of energy flow and transformation 
                                                                    within, through, and between organisms... 
           "cells do not produce energy - they consume energy"

UNITY comes from the fact that the mechanisms of

                         energy change and flow are NOT different

                                            among different life forms, but are the SAME

METABOLIC PATHWAYS - chemical reactions that produce useable cell energy

            ... pathways used by cells are all the same in bacteria, plants and animals.

              

glycolysis,   Krebs's cycle,   oxidative phosphorylation,  &     photosynthesis   ARE UNIVERSAL

   Unity...chemical reactions of life are the same in bacteria, plants, animals 

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the CELL is FUNCTIONAL UNIT of LIFE & of all known LIVING SYSTEMS

CELL THEORY is to BIOLOGY as ATOMIC THEORY is to PHYSICS

Definitions of a Cell :            A particular organization of        matter, bounded by a selectively        permeable membrane, that is        capable of self-reproduction,        without the presence of other        living organism. (eliminates viruses).		"Living organisms are composed of   inanimate molecules... and nothing is   alive in a cell except the whole of it?"          Matrin Olomucki (1993)             The chemistry of life.  NY, McGraw Hill
*
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