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Prelim 2 (LEC 10-11)
| Question | Answer |
|---|---|
| Is the 4 electron reduction of O2 energetically favorable or un-favorable? | favorable |
| What makes diatomic oxygen unusual? | two free electrons in lowest energy state |
| What is the Pasteur point? | The point at which respiration switches from anaerobic to aerobic (0.2%) |
| What is a respiratory shield and why is it formed? | consumption of O2 at the surface to maintain low internal O2 levels and allow O2 sensitive enzymes to function |
| What kind of cofactors do enzymes inactivated by O2 have? | metal |
| What is the even more reactive species that comes from oxygen? What is their role? | reactive oxygen species (ROS), kills bacteria |
| Which gas is the most abundant in the atmosphere? (N2, O2, or CO2) | N2 |
| Which enzyme fixes nitrogen? | nitrogenase |
| How is nitrate (fixed nitrogen) created? | Through symbiotic partnerships with Rhizobacterium. |
| Nitrogen fixation is an energy ____ (intensive or favorable) process and nitrogenase is easily inactivated by ______. | intensive, O2 |
| Which O2 binding protein produced by legumes protects nitrogenase? | leghemoglobin |
| What is facultative bacteria? What atmospheric O2 did they evolve at? | bacteria that can grow aerobically and anaerobically, 1% PAL |
| What atmospheric O2 did multicellular animals evolve at? | 3-10% PAL |
| What does O2 inhibit? | N2 fixing, CO2 fixing, |
| What leads to oxidative stress and ROS? | Incomplete reduction of O2 during respiration |
| Which organisms have nitrogenase? | diazotrophs |
| Cyanobacteria (and diazotrophs) must separate ___ from ___. | nitrogenase, OEC |
| Photosynthesis and nitrogen-fixation must be ___ (together or separate) in diazotrophs. | Seperate |
| What are the two kinds of photosynthesis/nitrogen-fixation seperation? | spatial (anabaena) and temporal, Fe sharing mechanism (crocosphaera) |
| What element is shared in temporal separation? | Fe (iron) |
| Which highly abundant enzyme is at the base of the food chain? | RuBisCo |
| Which enzyme drives the reversible hydration of CO2? What is the other output? | carbonic anhydrase, carbonic acid |
| What is the RuBisCo substrate? | CO2 |
| What do carbon concentrating mechanisms do? | enhance efficiency of photosynthesis (carboxysomes, pyrenoids) |
| What are the 4 basic elements of life? | CHNO |
| Is the earth's atmosphere in thermodynamic equilibrium? | No |
| When did photosynthetic organisms emerge? | end of archean, start of proteozoic |
| Name 2 oxygen carrier proteins | hemoglobin, myoglobin |
| What is a branched respiratory system? | where e- can flow to either terminal acceptor |
| What is the hypothesis regarding evolution stalling during the Proterozoic? | O2 inhibition of nitrogenase |
| What is the name for the evolutionary explosion? What caused it? | Cambrian explosion, warming, higher O2 in ocean (3-10%), creation of shallow-water marine habitats |
| What is the name of the largest extinction in history? What caused it? | Permian extinction, CO2 expulsion from oceans and acidic oceans |
| What evolved during the Cambrian Explosion? | evolution of circulatory system, O2 carrier proteins |
| O2 is ___ (highest or lowest) at lung and ___ (highest or lowest) at mitochondria. | highest, lowest |
| Reduction of O2 requires __ electrons | 4 |
| Respiration maintains a "microaerobic environment" that stabilized the __ required. | Fe |
| What are diazotrophs? | organisms that feed on N2 gas |
| N2 is __ (very or not very) stable | very |
| Nitrogen fixation is energetically ___ (favorable or costly). | costly |
| Nitrogen fixation requires __ pressure and ___ temperature (high or low). | high, high |
| Which elements are required for nitrogenase activity? | Fe and Mo |
| What is the Haber-Bosch process? | high pressure synthetic nitrogen fixation using Fe |
| What do globins do? | bind O2 to allow nitrogenase function |
| What are specialized, N2 fixing cells called? | Heterocysts |
| Respiratory shields depend on: | O2 diffusion barrier and active respiration |
| Crocosphaera watsonii is an example of a ____ organism that uses ____ during the day and ____ at night. | diazotrope, photosynthesis, N2 fixation |
| Crocosphaera watsonii uses Fe in enzymes for ____, then reuses same Fe for ____. | photosynthesis, nitrogenase |
| Co2 gas is incorporated into organic matter by _____. | autotrophs |
| What kind of organisms use photosynthetic CO2 fixation? | phytoplankton (water surface) and plants |
| Is photosynthesis more efficient in the ocean or on land? | Ocean |
| Oxygenation is also known as: | photorespiration |
| RuBisCo is a ___ (slow or fast) enzyme. | slow |
| RuBisCo has a ___ (high or low) affinity for CO2. | low |
| Name 4 CCMs | carbonic anhydrase, active transport of bicarbonate, morphological, biochemical |
| CO2 accumulates in _____. | carboxysomes |
| Carboxysomes immediately capture ___ after production for ____ fixation. | CO2, carbon |
| Spatial vs. Temporal separation of cycles: | steps occur in different types of cells, steps occur in same cell at different times |
| How does C4 photosynthesis reduce photorespiration? | concentrates CO2 around RuBisCO |
| Solubility is determined by these 4 factors: | salinity, pressure, temperature, and the gas |
| At higher temperatures, solubility is ___ (high or low) | low |
| At higher pressures, solubility is ___ (high or low) | high |
| At higher salinity, solubility is ___ (high or low) | low |
| What is kind of protein is hemocyanin? | O2 binding protein |
| What does hemocyanin do? | Bind O2 between two copper atoms |
| Which animals have hemocyanin? | mollusks and some insects |
| What color is hemocyanin? | blue |
| What are the tracheal tubes? and in which animals? | the tracheal tubes supply O2 directly to body cells |
| In insects, the respiratory and circulatory systems are ___ (integrated or seperate) | seperate |
| Tracheoles direct connect directly to cells (T or F) | true |
| ____ (small or large) animals obtain O2 by diffusion | small |
| Evolution of larger animals required ____ (higher or lower) levels of atmospheric oxygen | higher |
| Where in the lungs are gases exchanged by diffusion? | Alveoli |
| What are the two steps (pressure changes) in alveoli O2 uptake? | 1) PO2 drops, PCO2 rises 2) PO2 goes up, PCO2 goes down |
| What is dead space? | the fraction of air not efficiently exchanged? |
| What is the Bohr equation? | Vd/Vt = PaCO2-PeCO2/PaCO2 |
| What is CO2 converted to for transport to the lungs? | bicarbonate |
| what transforms CO2 and water to HCO3- (bicarbonate) + H+ | carbonic anyhydrase |
| Where does bicarbonate accumulate before moving to blood plasma? | RBC |
| Ins and outs of the chloride/bicarbonate anion exchanger are: | in: 1 HCO3- (into RBC) out: 1 Cl- |
| the chloride/bicarbonate exchanger ____ (raises/lowers) the pH of the circulating plasma | lowers |
| What is the principal signal to increase respiration? | low blood pH |
| When [CO2] rises in blood, blood pH ____ (raises/lowers) and respiration _____ (increases/decreases) | lowers, increases |
| What part of the brain detects decrease in pH? | medulla |
| What are the two sensors of blood pH? | medulla and blood vessels |
| What does the medulla signal when blood pH is low? | rib muscles and diaphragm (for higher respiration rate) |
| O2 levels in alveoli are diluted because of: | mixing with "used" air |
| What is the efficiency of O2 removal from air? | 25% |
| What is the efficiency of CO2 release? (alveoli) | 10% |
| CO2 is transported as ___ into plasma and bound to ____ | bicarbonate, hemoglobin |
| What kind of protein is myoglobin? | carrier protein |
| What does myoglobin do? | binds O2 released from hemoglobin |
| As the circulatory system approaches the tissue, O2 saturation ____ (decrease/increases). | decreases |
| Which has a higher O2 affinity? (hemoglobin or myoglobin) | Myoglobin |
| What is positive cooperativity? How is it relevant? | When the bonding gets stronger per bond, hemoglobin is a tetramer with cooperative binding. |
| What is hemoglobin's protein structure? | Tetramer |
| What happens to hemoglobin when it bonds O2? | allosteric transition from T state (deoxyhemoglobin) to R state (hemoglobin) |
| What is the benefit of positive cooperativity? | enhances O2 delivery to tissue |
| What does the Bohr effect explain? | lower pH , O2 binding is weakened |
| Bohr effect: ____ pH, stronger O2 binding (___affinity) | higher |
| What generates carbonic acid? | carbonic anhydrase |
| Name 2 things that trigger O2 release | protonation of Hb, CO2 modification of Hb |
| How many CO2s can each Hb tetramer carry? | 4 |
| What stabilizes deoxyhemoglobin at low pH? | a salt bridge (protonated) |
| What kind of regulation is rxn of CO2? | Allosteric |
| What binds at the center of hemoglobin to allosterically regulate O2 binding? | 1,3 BPG |
| 2,3 binding ___ (increases/decreases) O2 affinity | higher |
| What is the function of fetal hemoglobin? | facilitates O2 transfer to embryo |
| What is a heme cofactor? | porphyrin ring with central Fe atom |
| How does the heme cofactor in Hb bind O2? | reversibly |
| Which 3 things allosterically regulate binding of Hb to O2? | pH (Bohr), CO2 (protein modification), 2,3 BPG |
| Gills allow fish to have ____ (efficient/inefficient) gas exchange of __% | efficient, 80 |
| What makes gills able to exchange gas so efficiently? | large surface area |
| Air flow is _____directional (uni or bi) in birds | uni |
| What benefits does unidirectional airflow have | eliminates mixing |
| In birds, where does air go before the lungs? | posterior air sac |
| In birds, what is the path of air? | posterior air sacs, lungs, anterior air sacs |
| While mammals use alveoli for gas exchange, birds use ____. | Parabronchi |
| While mammals use ____ for gas exchange, birds use parabronchi. | Alveoli |
| Air flow is _____directional (uni or bi) in mammals | bi |
| Animals that exist at higher altitudes, reach higher O2 saturation of Hb at _____ (higher/lower) pressures. | lower |
| What kind of exchange is used in fish for respiration? | counter-current exchange |
| Why do people at high altitudes require more Hb? | bc O2 saturation of hemoglobin happens much faster at high altitudes |
Created by:
shohumfin
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