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46 Cards in this Set

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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?
Positive?
-exergonic
-endergonic
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
-Oxidative
-Photophosphorylation
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?
Anaerobic?
Fermentation?
-36 to 38
-2 to 36
-2
What are the three pathways for respiration from start to finish?
-glycolysis
-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?
-34
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
-dinitrophenol
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?
Propionibacterium
Bacillus/Lacto/strepto
Saccharomyces
Clostridium
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?
Eukaryotes?
-invagination of cytoplasmic membrane
-formed from infoldings of inner membrane of chloroplasts
What are the two types of photosystems?
-PS I
-PS II
What is used to generate ATP in photophosphorylation?
-proton motive force
What are two types of photophosphorylation?
-cyclic
-noncyclic
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.
.