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46 Cards in this Set

  • Front
  • Back
What are key points to defining/explaining bioenergetics?
-how cells use biochemical reactions (metabolism) to obtain energy
-associated with breaking of covalent bonds which releases energy
-released energy is trapped of dissipated as heat
-available energy is free energy (G) in kJ
When delta G is negative what is it?
What is activation energy?
-the energy required to bring reactants to the reactive state
*catalyst in chemical reactions
*enzymes in cellular reactions
What is an enzyme for?
-increases speed or rate of reaction
-NOT altered in reaction
Describe an enzyme.
-usually a protein (except catalytic RNA)
-specific for a given substrate becuase of its tertiary/quaternary structure
What is the reduction potential?
-a measurement in volts of tendency to become oxidized or reduced
*the greater reduction potential between reactants, the greater the energy released!
What does NAD+ stand for?
-Nicotinamine adenine dinucleotide
What is NAD?
-an electron carrier that's freely diffusable in a cell
-When oxidized, it accepts and transports electrons and hydrogens
-when reduced, donates them
-NAD/NADH-energy generating catabolic pathways
-NADP/NADPH-anabolic pathways
How does NAD work as a coenzyme?
-it is regenerated after acting as a coenzyme in a two-part reaction
How is energy from redox reations retained?
When is it released?
-put in high-energy phosphate bonds (can be easily released for anabolic reactions)
-hydrolysis of phosphate bond
Which bond releases more energy when phosphate is hydrolized?
-anhydride bonds (unstable) release more than ester bonds
What are the three levels of phosphorylation?
-Substrate level
What happens in substrate level phosphorylation?
-ATP is synthesized in steps in catabolism of organic molecule through transfer from phosphorylated intermediates
What happens in oxidative AND photophosphorylation?
-ATP is synthesized by membrane bound ATP synthase coupled to the protonmotive force
How much ATP is produced in aerobic respiration?
-36 to 38
-2 to 36
What are the three pathways for respiration from start to finish?
-synthesis of acetyl CoA and Krebs cycle
-Aerobic electron transport chain
What do you get from gycolysis in terms of ATP and NADH?
-2 of each molecule
*look up for detailed reactions
Why is more ATP generated through respiration compared to fermentation?
-organic molecule is completely oxidized to CO2
-greater difference in reduction potentials between donor and terminal electron acceptor (O2): occurs in aerobic bacteria, eukaryotic mitochondria
Draw the sythesis of acetyl-CoA
Draw Krebs cycle
What couples ATP synthesis to redox reations in respiration?
-through a membrane-bound electron transport chain
What are 5 electron carriers?
1) NADH dehydrogenase
2) Flavoproteins
3) Iron-sulfur proteins
4) Cytochromes-heme
5) Quinones-nonprotein
*see E and B lecture for diagrams
What is chemiosmosis?
-coupling of protonmotive force to ATP synthesis which using F1/F0 ATP synthase
How does chemiosmosis work?
-H+ ions flow down electrochemical gradient (propelled by prton motive force) through ATP synthases that phosphorylate ADP to ATP
How many molecules at ATP are formed from one molecule of glucose?
What creates the proton gradient in chemiosmosis?
What's this called?
-created by oxidation of components of electron transport chain
-called oxidative phosphorylation
What do inhibitors do in chemiosmosis? Which ones?
-block electron flow
-CO, CN (inhibit cytochromes)
What do uncouplers do in chemiosmosis?
Which one?
-prevent ATP synthesis without affecting electron flow
What are three random facts about fermentation?
-regeneration of NAD+ for use in ATP production during glycolysis
-allows ATP sythesis in the absence of respiration
-byproducts are not useful to microbes (waste products) but are for humans!
What fermentation product does each one make from pyruvic acid?
E. acetobacter
-CO2 propionic acid (swiss cheese)
-lactic acid
-CO2 ethanol
-acetone, isopropanol
-acetic acid
In photosynthetic anabolism, what do organisms do first?
Then what?
-synthesize organic molecules from inorganic CO2
-many capture light energy to get carbohydrates from CO2 and water (AKA photosynthesis)
How do organisms catch light energy?
-use pigment molecules (most importantly chlorophylls)
-varying length adn structure of chlorophylls and their tails cause different wavelengths to be absorbed
What are chlorophylls composed of?
-hydrocarbon tail attached to light-absorbing active site centered around manesium ion
What are photosystems?
-light harvesting matrices that contain chlorophyll molecules and found embedded in cellular membranes called thylakoids
How are thylakoids formed in prokaryotes?
-invagination of cytoplasmic membrane
-formed from infoldings of inner membrane of chloroplasts
What are the two types of photosystems?
What is used to generate ATP in photophosphorylation?
-proton motive force
What are two types of photophosphorylation?
What are light independent reactions?
-do not require light directly but use ATP and NADPH generated by light dependent reactions
What is the key reaction for light independent reactions?
-carbon fixation by Calvin Benson cycle
Describe carbon fixation using the Calvin Benson cycle
-for every 3 CO2 that enter cycle, one molecule of glyceraldehyde 3-phosphate leaves
-for every two of these, onle molecule of glucose 6-phosphate in anabolically synthesized by glycolysis
What do anabolic reacions require and why?
-energy and source of metabolites because it is a synthesis reaction
How do anabolic reactions compare to catabolic pathways?
-often the reversal of them
What are amphibolic reactions?
-can prceed in either direction
What three pathways provide the basic precursers to which all macromolecules and structures are made? How many?
-Glycolysis, the Krebs Cycle, and the pentose phosphate pathway
-12 precursers
See simplified view of central metabolism in E and B lecture.