The Fundamental problem for cells: most of the molecules in the cell (proteins, nucleic acids, polysaccharides, etc.) must be made by joining monomers (amino acids, nucleotides, monosaccharides) Endergonic reactions (need energy)Solution : transfer phospate group from ATP to another molecule produce energyenergy coupling.

DefinitionsMetabolism: The processes of catabolism and anabolismCatabolism: The processes by which a living organism obtains its energy and raw materials from nutrientsAnabolism: The processes by which energy and raw materials are used to build macromolecules and cellular structures (biosynthesis)

ENZIM : Suatu biokatalisator Fungsi : Menurunkan energi aktivasi ; reaksi berjalan cepat

Berdasarkan tempat kerja enzim :Endoenzim, enzim intraselulerEksoenzim, enzim ekstraseluler Faktor yang mempengaruhi kerja enzim:Konsentrasi enzim dan substratTemperaturpHKeberadaan inhibitor dan aktivatorAdanya induktor

Electron Carrier MoleculesNADPH, NADH molecule that accept electron from electron donors and donate them to electron acceptors

ENERGY PRODUCTION

Substrate level phosphorylation

2. Oxidative phosphorylation energy generated by passage of electrons through a series of e- donors and acceptors, and used to pump protons out of the cell proton motive force ATP generation by action of H+ - translocating ATPase also use of PMF for transport of substrates into cell

3. Photophosphorylation

Prokaryotes can be divided into various physiological groups based on howthey derive energy and assimilate carbon.

GroupCarbon fromEnergy byChemolithotrophs CO2oxidation of inorganiccompoundsPhotolithotrophs CO2lightChemoheterotrophs organic compoundsoxidation of organiccompoundsPhotoheterotrophs organic compoundslight

Features of glycolytic pathways :Partial oxidation of glucose to form pyruvic acid A small amount of ATP is made A small amount of NAD is reduced to NADHGlycolytic Pathways

4 major glycolytic pathways found in different bacteria:Embden-Meyerhoff-Parnas pathwayClassic glycolysisFound in almost all organismsHexose monophosphate pathwayAlso found in most organismsResponsible for synthesis of pentose sugars used in nucleotide synthesisEntner-Doudoroff pathwayFound in Pseudomonas and related generaPhosphoketolase pathwayFound in Bifidobacterium and Leuconostoc

The Embden-Meyerhoff-Parnas pathway

Hexose monophosphate pathway

The Entner-Doudoroff Pathway

The Phosphoketolase pathway

Features of fermentation pathwaysPyruvic acid is reduced to form reduced organic acids or alcohols.The final electron acceptor is a reduced derivative of pyruvic acidNADH is oxidized to form NAD: Essential for continued operation of the glycolytic pathways.O2 is not required.No additional ATP are made.Gasses (CO2 and/or H2) may be releasedFermentation

Examples of fermentation pathwaysLactic acid fermentationFound in many bacteria; e.g. Streptococcus cremoris, Lactobacillus acidophilusMixed acid fermentatione.g. Escherichia coliBasis of the methyl red test2,3-Butanediol fermentation e.g. Enterobacter aerogenesBasis of the Voges-Proskauer reactionFermentation

Model fermentation

RespirationPyruvic acid is oxidized completely to CO2.The final electron acceptor is usually an inorganic substance.NADH is oxidized to form NAD.O2 may or may not be required.Aerobic respiration: O2 is the final e- acceptor.Anaerobic respiration: An substance, usually inorganic, other than O2 is the acceptor (nitrate, nitrite, sulfate)A lot of additional ATP are made (up to 36 per glucose molecule).

Model of Aerobic respiration.

Stages of RespirationPreliminary reactions and the Krebs cycle (TCA or Citric Acid Cycle)Respiratory electron transport

Electron transport system

Anaerobic Respiration Respiration in some procaryotes is possible using electron acceptors other than oxygen (O2).

anaerobic respiration use of some compound other than O2 as a final electron acceptor in the electron transport chain.

Electron acceptors for respiration and methanogenesis in procaryotes

electron acceptorreduced end productname of processorganismO2H2Oaerobic respirationEscherichia, StreptomycesNO3NO2, NH3 or N2anaerobic respiration: denitrificationBacillus, PseudomonasSO4S or H2Sanaerobic respiration: sulfate reductionDesulfovibriofumaratesuccinateanaerobic respiration: using an organic e- acceptorEscherichiaCO2CH4methanogenesisMethanococcus

Light-dependent Reactions: Light energy is harvested by photosynthetic pigments and transferred to special reaction center (photosystem) chlorophyll molecules.

The light energy is used to strip electrons from an electron donor (the electron donor goes from a reduced to an oxidized state).Photosynthesis

The electrons are shuttled through a series of electron carriers from high energy state to a low energy state.

During this process, ATP is formed.

In the cyclic pathway of electron transport, electrons are returned to the electron transport chain In the noncyclic pathway, the electrons are used to reduce NAD (or NADP) to NADH (or NADPH)

ATP and NADH (NADPH) from the light-dependent reactions are used to reduce CO2 to form organic carbon compounds (carbon fixation).

The reduced organic carbon is usually converted into glucose or other carbohydrates.

Oxygenic photosynthesisFound in cyanobacteria (blue-green algae) and eukaryotic chloroplastsElectron donor is H2O: Oxidized to form O2Two photosystems: PSII and PSIMajor function is to produce NADPH and ATP for the carbon fixation pathways

Electron flow in plant (oxygenic) photosynthesis

Anoxygenic photosynthesisFound in:Green sulfur bacteria (Chlorobium)Green nonsulfur bacteria (Chloroflexus)Purple sulfur bacteria (Chromatium)Purple nonsulfur bacteria (Rhodobacter)

Anoxygenic photosynthesis Electron donors vary:H2S or So in the green and purple sulfur bacteriaH2 or organic compounds in the green and purple nonsulfur bacteria

Only one photosystem

In green bacteria, the photosystem is similar to PSI- In purple bacteria, the photosystem is similar to PSIIPrimary function is ATP production, chiefly via cyclic photophosphorylation

The cyclical flow of electrons during bacterial (anoxygenic) photosynthesis

Differences between plant and bacterial photosynthesis

plant photosynthesisbacterial photosynthesisorganismsplants, algae, cyanobacteriapurple and green bacteriatype of chlorophyllchlorophyll a absorbs 650-750nmbacteriochlorophyll absorbs 800-1000nmPhotosystem I (cyclic photophosphorylation)presentpresentPhotosystem I (noncyclic photophosphorylation)presentabsentProduces O2yesnoPhotosynthetic electron donorH2OH2S, other sulfur compounds or certain organic compounds

Biosynthesis