Photosynthesis and Respiration

I.         Energy for Life

            A.        Photosynthesis

                        1.         Store solar energy in bonds of carbohydrates

                        2.         Light-dependent reactions (thykaloid space)

                        3.         Light-independent reactions (in stroma)

                        4.         Autotrophs

            B.        Respiration

                        1.         Releases energy from bonds

                        2.         Produces ATP

                        3.         Autotrophs and heterotrophs

            C.        Adenosine TriPhosphate (ATP)

                        1.         Vector for energy transfer

                        2.         Produced in mitochondria

            D.        Biochemical Pathway

                        1.         Sequence of reactions

                        2.         See page 95

II.        Photosynthesis

III.       Chloroplast Structure

            A.        Inner membrane: made of grana

            B.        Grana: stacks of thykaloid disks

            C.        Stroma: protein rich solution around thykaloid disks

            D.        Thykaloid: membrane has ATP synthase and cholorphyll

IV.      Pigments

            A.        Chemicals that absorb light

            B.        Color is unabsorbed light

V.        Chloroplast Pigments

            A.        Cholorphylls

                        1.         a: absorbs red, directly involved in light reactions

                        2.         b: absorbs blues, aids chlorophyll a

                        3.         Produces green color

            B.        Carotenoids

                        1.         Absorb blue and green

                        2.         Produces fall colors

VI.      Light Reactions (LR)

            A.        5 step process

            B.        Produces reactants for dark reactions

VII.     Photosystem II

            A.        Light excites electron in chlorophyll

            B.        Electron is passed to primary acceptor molecule (NAD)

            C.        Electron is transported to photosystem I, p+ transported to thykaloid

VIII.    Photosystem I

            A.        Light excites electron in chlorophyll and e- is passed to acceptor

            B.        Electron is tranported to thykaloid to produce NADP

            C.        NADP used in Calvin Cycle

IX.      Restoration fo System II

            A.        H₂O split in thykaloid membrane

            B.        H⁺ used in system I to produce NADP

            C.        O₂ excreted as waste product

            D.        e^- replaces electrons in system II

X.        Phosphorylation (Chemiosmosis)

            A.        Produces ATP to power dark reactions (Calvin Cycle)

            B.        Electron transport chain creates H⁺ gradient across memrane

            C.        ATP synthase uses energy of gradient to convert ADP to ATP

XI.      Light Independent (Dark) Reactions

            A.        Use energy from light reactions (ATP, NADPH)

            B.        Produce Carbohydrates

            C.        Calvin Cycle

            D.        C₄ Pathway

            E.        CAM

XII.     Calvin Cycle

            A.        3 step process

            B.        Reactants: ATP, NADPH, CO₂, H⁺, H₂O

            C.        Products: carbohydrates, P, ADP, NADP

            D.        Intermediates PGAL and RuBp recycled

XIII.    Calvin Cycle (step 1)

            A.        CO₂ enters stroma and binds to RuBp (C₅ sugar)

            B.        Divides to form 2 PGA (C₃)

XIV.   Calvin Cycle (step 2)

            A.        PGA form PGAL

                        1.         P from ATP joins PGA

                        2.         H⁺ from NADPH joins PGA

            B.        Consumes PGA, ATP, and NADPH

            C.        Produces PGAL, ADP, NADP, P

XV.     Calvin Cycle (step 3)

            A.        2 PGAL molecules join to form carbohydrates

            B.        Remaining PGAL reform as RuBP

            C.        Uses energy from ATP

XVI.   C4 Pathway

            A.        Occurs with high temperature, dry conditions, abundant light

            B.        CO₂ forms 4 carbon compound

            C.        Input to Calvin cycle vice CO₂

            D.        More efficient but higher energy cost

XVII.  CAM

            A.        Hot/dry climates

            B.        CO₂ taken in at night, less water loss

            C.        Stored as organic acid CAM

            D.        Released to Calvin Cycle during day

XVIII. Respiration

XIX.   Cellular Respiration

            A.        Production of ATP from organic compounds

            B.        Sequence of chemical reactions

            C.        Produce energy from glucose

            D.        NAD and FAD electron receptors in transport chain

            E.        H⁺ sets up gradient

XX.     Definitions

            A.        Anaerobic: reactions that occur without O₂

            B.        Aerobic: reactions that require O₂

XXI.   Glycolysis

            A.        Occurs in cytosol

            B.        Beginning of both pathways

            C.        Breakdown of glucose to pyruvic acid

XXII.  Reactancts:

            A.        1 glucose molecule

            B.        2 ATP molecules

XXIII. Products:

            A.        2 pyruvic acid molecules

            B.        4 ATP molecules

XXIV. Step 1

            A.        2 ATP molecules phosphorylate glucose

            B.        Glucose forms 2 molecules of PGAL

XXV.  Step 2

            A.        NAD and P from Calvin cycle remove H⁺ and add P to PGAL

XXVI. Step 3

            A.        PGAL changes to pyruvic acid

            B.        4 ATP molecules formed

XXVII.           Fermentation (Anaerobic)

            A.        Occurs in cytoplasm

            B.        Regenerates NAD for Glycolysis

            C.        Produces lactic acid or ethanol

XXVIII.          Lactic Acid

            A.        In animal cells when O₂ not present

            B.        NADH gives up H⁺ to pyruvic acid producing lactic acid and NAD

            C.        NAD passed to glycolysis

            D.        Lactic acid stored in liver and muscle tissue until O₂ available

            E.        Build up of lactic acid causes muscle soreness

XXIX. Ethanol

            A.        Occurs in plants when O₂ not present

            B.        NADH gives up H⁺ to pyruvic acid

            C.        Ethanol, CO₂, and NAD produced

XXX.  Aerobic Respiration

            A.        O₂ is present

            B.        Occurs in mitochondria

            C.        Steps 1 and 2 in matrix

            D.        Step 3 on inner membrane

XXXI. Step 1

            A.        Pyruvic acid loses CO₂ and H⁺ forming acetyl group

            B.        Acetyl group bond with Coenzyme A to form acetyl-CoA

            C.        H⁺ binds with NAD to form NADH

XXXII.           Step 2: Krebs Cycle

            A.        Releases 4 molecules CO₂ and H⁺

            B.        Produces 2 molecules ATP

XXXIII.          Krebs Cycle step a

            A.        Acetyl-CoA combines with 4-carbon acid

            B.        Citric acid (C₆) produced

            C.        CoA released

XXXIV.          Krebs Cycle step b

            A.        NAD takes H⁺ and forms NADH

            B.        CO₂ released

            C.        5-carbon acid produced

XXXV.           Krebs Cycle step c

            A.        NAD takes H⁺ and forms NADH

            B.        CO₂ released

            C.        ATP produced

            D.        4-carbon acid produced

XXXVI.          Krebs Cycle step d

            A.        FAD takes 2H⁺ to form FADH₂

            B.        4-carbon acid formed

XXXVII.        Krebs Cylcle step e

            A.        NAD takes H⁺ to form NADH

            B.        New 4-carbon acid forms

            C.        Cycle repeats

XXXVIII.       Step 3: Electron Transport Chain

            A.        Occurs in membrane of mitochondria

            B.        NADH and FADH₂ provide electrons to transport chain

            C.        Creates H⁺ gradient

            D.        Chemiosmosis

                        1.         Movement of H⁺ powers ATP synthase

                        2.         ATP synthase makes ATP

            E.        Products: ATP and water

XXXIX.          Total yield

            A.        Glycolysis                    2 ATP

            B.        Krebs Cycle                 2 ATP

            C.        Electron Transport      38 ATP