Review Sheet B Test #2      BIOLOGY 1107            Dr. James K. Adams

Cell Structure and Function -- see previous review sheet
Prokaryotic vs. Eucaryotic cells

Cell membrane - fluid mosaic model
            I.  Lipids
                     A.  Phospholipid bilayer
                 B.   cholesterol
            II.  Proteins
   Extrinsic/intrinsic proteins
                     B.   Filaments of the cytoskeleton
            III.  Carbohydrates
                              Glycocalyx in animal cells (cell-cell recognition) -- "fuzzy coat" of
                                 glycolipids/glycoproteins; each cell type unique

Plant cells also have a cell wall (cellulose), with holes from cell to cell (plasmodesmata)

Junctions: Tight, Gap, Desmosomes, plasmodesmata

Cell membrane is semipermeable (selectively/differentially permeable)
     regulates movement of molecules into and out of cells

Transport of materials through membrane:
I.  Passive processes: No energy required
     A. Diffusion -- movement of atoms/molecules down a concentration gradient 
               Osmosis -- water (or some solvent) diffusing through a semipermeable membrane
                            water typically follows solutes if solutes are moved
     Understand the meaning of hypo-/iso-/hypertonic solutions
     B. Facilitated diffusion -- uses carrier proteins to move substances with the gradient
II.  Active processes: Energy (ATP) required
     A.  Active transport -- also uses carrier proteins, but moves materials against the gradient
                 example: Na+ - K+ pump
     B.  Bulk Transport
           1.Endocytosis - bulk transport into the cell
                 a.  Phagocytosis
                    b.  Pinocytosis
                 c.  Receptor-mediated endocytosis
           2.  Exocytosis - Bulk transport out of the cell

Cell Energetics -- Energy Transformations (includes Photosynthesis and Cellular Respiration)
     Energy - capacity to do work (move matter)
         States: kinetic (in action) or potential (stored)
         Types - radiant (light), electrical, mechanical, chemical, thermal (heat)

Laws of Thermodynamics:
     1. First: Energy Finite (can
=t be created or destroyed) but convertible
     2. Second: Every conversion increases entropy (some energy lost as heat during any conversion)

Chemical Reactions: all reactions require some initial input of energy (energy of activation -- Ea)
        1. synthesis - requires a net input of energy               (endergonic)
            2.  degradation/decomposition - liberates energy       (exergonic)
  exchange - energy balance depends on reactants (substrates) and products
    Concepts:   Endergonic/Exergonic reactions - Coupling of reactions;
                       Free energy of the reaction

Enzymes and Enzyme function: Virtually all reactions in the body require enzymes
Do not change equilibrium of reactants (substrates) and products, or the free energy
        Do speed the rate of reactions (catalysts) by reducing the Ea (energy of activation)
    Active site
    Inhibitors - competitive/non-competitive; many enzymes inhibited by negative feedback

Reduction/Oxidation reactions (Redox): generally occur together
reduction - gaining electrons/energy; oxidation - losing electrons/energy
                 protons (H+) often get passed with electrons
          Electron (energy) carriers :   NADPH + H+, NADH + H+ and FADH2
See how these electron carriers are used in electron transport chains in both Photosynthesis and
Cellular Respiration, below, to help generate

Photosynthesis - SEE OTHER HANDOUTS - anabolic set of reactions - synthesis of glucose
          Photosynthesis converts light energy to chemical energy

Leaves - main organ of photosynthesis (see also Chapter 33, page 718)
     upper/lower epidermis, with stomates for exchange of CO2 (in)/water (out)
  pallisade/spongy parenchyma - photosynthetic (mesophyll); contains chloroplasts
             Chloroplasts have stroma/thylakoids

I.    The Light Dependent Reactions - cyclic/non-cyclic photophosphorylation
        Involves electron transport across the thylakoid membranes electrons excited by light energy
     H2O is the initial electron donor (O2 released); NADP+ is the final electron acceptor
     ATP formation (phosphorylation) coupled to movement of protons (H+=s) --
             Chemiosmosis -
movement of protons through a semipermeable membrane

II.   The Light Indpendent Reactions or the Calvin Cycle (CC) -- The Carbon fixation steps
     These steps are responsible for fixing CO2 into glucose, these steps don't require light
        . . . except to activate Rubisco ; in other words this enzyme is light-activated         
               Rubisco - Ribulose bisphosphate carboxylase/oxygenase
                 This enzyme (most abundant protein in the world) fixes CO2 (and also O2)
      A.  C3 PS - Uses Calvin Cycle only; found in cool, moist adapted plants
      B.  C4/CAM PS - Uses PEPC (phospho-enol pyruvate carboxylase) also
                PEPC is not light activated B when carbon dioxide first fixed, it is attached to a
                         four-carbon molecule; then passed to a different cell (bundle sheath)
             The fixed CO2 is then released and refixed by Rubisco to make glucose in the CC
                In other words, these plants use a CO2 shuttle, but still use CC to make glucose
                Found in warm, dry adapted plants
         CAM plants use PEPC, just like C4 plants, but fix CO2 at night to avoid water loss

Cellular Respiration - SEE HANDOUTS - catabolic set of reactions; breaks down glucose  
            to get energy
; occurs in all organisms - plants, animals, etc.

I.  Glycolysis - in cytoplasm
     if anaerobic (no O2), followed by fermentation - also in cytoplasm
     if aerobic (with O2), followed by the following two sets of reactions . . .

II.  Krebs=/TCA (tricarboxylic acid)/Citric Acid Cycle
            pyruvate moves into inner matrix of mitochondria, where TCA cycle takes place
            requires decarboxylation (removal of CO2) to form 2C Acetyl CoA to enter cycle

III. Oxidative Phosphorylation -- follows TCA cycle (with O2); involves electron transport chain  
            (in cristae of mitochondria); generates ATP (similar to the light reactions of PS)
     As before, ATP formation (phosphorylation) coupled to proton (H+) movement -    
        Initial electron donor is NADH + H+; final electron acceptor is O2 (last step generates water)
  Fats and Proteins can be hydrolized and utilized, entering the cellular respiratory reactions at      
           different places: