Chapter 13/14 Flashcards
Describe the general idea behind biological oxidations. What is removed or gained? What are they usually catalyzed by?
Biological Oxidations remove protons, remove electrons, and are usually catalyzed by dehydrogenases
Oxidations in general add oxygen, remove hydrogen, and remove electrons
Describe the ability of bacteria to perform oxidative respiration
Bacteria can perform oxidative respiration even though they do not have mitochondria. They use a plasma membrane instead of the mitochondrial membranes.
Give the general equation behind cellular respiration
Sugar (C6H12O6) + O2 –> Oxidation -»»» CO2 + H2O
Describe the general equation for Glycolysis (i.e. the starting materials and products). Where does Glycolysis occur? What can enter and where?
Glucose + 2 ATP → 2 Pyruvate + 2 NADH + 4 ATP
Series of 10 reactions catalyzed by 10 enzymes
Occurs in cytosol
Other sugars can enter as glucose or as intermediates, amino acids enter as pyruvate and fatty acids enter as acetyl CoA
Describe NAD+. What is it classified as? What special thing is it made out of?
A coenzyme (non-protein compound required for enzymatic reaction) that serves as an electron acceptor in biological oxidations.
Reduced during aerobic respiration to NADH
B-vitamin
What are the three main stages of Glycolysis? Describe them
- ) Investment of 2 ATP for 2 phosphorylations by kinases (enzymes that - P from ATP and → substrate)
- ) Cleavage of 6-carbon sugar to 2 3-carbon sugars
3.) Energy generation through
oxidation to generate NADH and ATP (substrate level phosphorylation)
In steps 6-7 (stage 3) High-energy thioester bond becomes high-energy phosphate bond
What occurs in Glycogenesis? Where does it occur and why?
Occurs in skeletal muscles during intense exercise, due to lack of glucose (low blood sugar)
Pyruvate produced by glycolysis is fermented to lactate -> Cells in liver turn lactate back to pyruvate -> Pyruvate back to glucose using 6 ATP
Includes 3 bypass reactions to avoid irreversible steps
Feedback allows cells to switch between glucose catabolism (lysis) and synthesis (genesis)
What molecules activate glycolysis? What molecules inactivate glycolysis?
Glycolysis is activated by ADP, AMP, and P and inactivated by ATP
What molecules activate glycogenesis? What molecules inactivate glycogenesis?
Glycogenesis is activated by ATP and inactivated by ADP, AMP, and P
Describe where animals store their energy. How much energy is stored in fat relatively speaking? What are fat cells called?
Animal cells store energy in glycogen (branched polysaccharide of glucose monomers)
Also store energy in fat droplets (triacylglycerols)
(1 gram of fat has 2x the energy of glycogen) fat cells are called adipocytes
Where do plants store energy
Plant cells store starch and fat in chloroplasts
Describe the fate of pyruvate in the presence of O2 (general, short)
Converted to acetyl CoA and enters the citric acid cycle
Describe the fate of pyruvate in the absence of O2 (general, short)
Undergoes fermentation to regenerate NAD+
Describe the process of Fermentation, including where it occurs and the two possible sets of products
Process of regenerating NAD+
Occurs in cytosol, no additional ATP generated
It can produce lactate during intense exercise
Or it can produce ethanol and CO2 (yeast)
Differentiate between the inner membrane and the outer membrane of the mitochondria
The inner membrane is the site of ATP synthsis and the electron transport chain due to its high density of proteins (intermembrane space), and that it is impermeable to ions (such as H+)
The outer membrane is more permeable (due to porins/beta barrels, other proteins)
Describe the general reaction/process of the pyruvate oxidation. Where does it occur? Give the general equation.
Pyruvate is oxidized in mitochondrial matrix by pyruvate dehydrogenase complex
3-C pyruvate + NAD+ + O2 → 2-C acetyl CoA + CO2 + NADH
Describe the general reaction/process of the Citric Acid Cycle. Where does it occur? Give the general equation, and describe produced molecules.
Acetyl CoA (2C) + Oxaloacetate (4C) → Citrate (6C)
Each turn of the cycle produces CO2, FADH2, GTP (substrate level, converted to ATP), and NADH
Most of the energy is now in FADH2 and NADH (high-energy electron carriers)
Occurs in mitochondrial matrix
Oxaloacetate is regenerated in the final step
Describe the Electron Transport chain. Where does it occur? What is it used for? What are the reactants and what are they converted into?
NADH and FADH2 are generated by glycolysis, pyruvate oxidation, and citric acid cycle and enter the electron transport chain
O2 is final electron acceptor (converts to H2O)
Energy of electron transport is used to pump protons across the membrane (From matrix through inner membrane to intermembrane space)
Define Respiratory Complexes. Describe the different ones (3)
NADH Dehydrogenase Complex
NADH electrons enter here (H- → Proton and 2 Electrons)
Cytochrome C Reductase Complex
FADH2 electrons enter here
Cytochrome C Oxidase Complex
Produce H2O from ½ O2 and 2 H+
Describe the two mobile carriers. What are their functions?
Ubiquinone: Small, hydrophobic, motile electron carrier molecule that picks up electrons from the NADH dehydrogenase complex and delivers them to the cytochrome c reductase complex
Cytochrome C: A cytochrome is a membrane-bound, colored, heme-containing protein that transfers electrons during cellular respiration
What is delta E? What is the equation for the delta E naught of a reaction consisting of an electron acceptor and an electron donor? What is the relationship between delta E naught and delta G naught? Where do electrons move spontaneously? (higher Eo or lower)
Bonus: How does this relate to FADH2 and NADH?
Redox potential
ΔE0 = E0 Electron Acceptor - E0 Electron Donor’
(will go from a low E0 to a high E0)
When ΔE0 is positive, ΔG0 will be negative
Electrons will move spontaneously to molecules with greater redox potential
FADH2 cannot donate to the same respiratory complex as NADH due to different redox potentials
Describe the function of ATP synthase. Where does it move things? What does it need?
Harnesses energy from proton gradient to make ATP by oxidative phosphorylation.
Reversible→ will follow H+ flow
ATP needs to be high, or else the mitochondria will stop working and the cell will die.
Describe the structure of ATP synthase.
F0 roter
Ring of c subunits that is powered by H+
Y/Gamma-subunit is a shaft (proton channel) that connects the rotor to the head, drives changes in b subunit
F1 head
Three a and three b catalytic subunits (b is the important one)
Describe the binding change model of ATP synthase
B catalytic subunit rotates through three conformations
Open, (O) → subunit can bind to ADP + P, ATP can exit
Loose, (L) → loose binding to ADP + P
Tight (T) → tight binding to ATP + P
Conformational changes are not required for proton movement through the channel, the other way around
Recognize the effect of cyanide and rotenone
Cyanide → Prevents production of final H2O product, causes buildup of NADH
Rotenone → Prevents movement past the first step of electron transport chain
What are the three general stages of aerobic respiration?
Breakdown of large macromolecules into simple subunits, further breakdown into acetyl CoA and the production of ATP/NADH, and the complete oxidation of acetyl CoA to CO2 (paired with reduction of O2 to H2O)
Glycolysis: 2 NADH and 2 ATP -> 5 ATP
Pyruvate Oxidation: 2 NADH -> 5 ATP
Acetyl CoA Oxidation: 6 NADH, 2 FADH2 and 2 GTP -> 20 ATP
How many ATP are made by oxidative phosphorylation? How many by substrate level phosphorylation
26
2
