From aerobic respiration

To make bread, fresh yeast is mixed with warm sugar solution and the mixture added to the flour. This dough mixture is then put into a warm place to rise. The dough rises due to the production of carbon dioxide from aerobic respiration (respiration with oxygen) by the yeast. The products of this style of respiration are different to those of anaerobic respiration. 

High yield of ATP from aerobic respiration made possible the development of typically eukaryotic features (Vellai et al. 1998). It is suggested that the last common ancestor of all eukaryotes was an aerobically respiring organism capable of complete oxidation of carbohydrates to carbon dioxide and water. Some unicellular eukaryotes have either retained or secondarily acquired the ability for anaerobic respiration and hydrogen-evolving fermentation, which has allowed their adaptation to life under microaerophilic or anaerobic conditions. 

Example 4.7. Decrease in pH from Aerobic Respiration What is the pH change resulting from the aerobic decomposition of organic matter—6 c r-... 

The amount of oxygen presently in the surface environment gives us an estimation of the amount of phototrophic biomass that has ever been produced and has been locked away from aerobic respiration by burial in sedimentary rocks. It is a minimum value because of the removal of oxygen into other sinks. Molecular oxygen (02) is not particularly soluble in water, so most of it resides in the atmosphere (1.2 X 1018 kg) rather than in the oceans (7.8 X 1015 kg). From Eqn 1.23 we can estimate the corresponding amount of phototrophic material that must have been produced as c. 1.1 X 1018... 

Energy Yields from Aerobic Respiration Some Alternatives... 

Aerobic respiration. Many organisms carry out aerobic respiration in which enzymes remove electrons from organic compounds and pass them through a chain of carriers including flavoproteins and cytochromes located in intracellular membranes (Fig. 3-4) until finally they are used to reduce oxygen to produce water. ATP is produced by an enzyme called ATPase, that is located in the cell membrane, and the process is driven by a proton gradient across the membrane. 

SRB, a diverse group of anaerobic bacteria isolated from a variety of environments, use sulfate in the absence of oxygen as the terminal electron acceptor in respiration. During biofilm formation, if the aerobic respiration rate within a biofilm is greater than the oxygen diffusion rate, the metal/biofilm interface can become anaerobic and provide a niche for sulfide production by SRB. The critical thickness of the biofilm required to produce anaerobie conditions depends on the availability of oxygen and the rate of respiration. The corrosion rate of iron and copper alloys in the presence of hydrogen sulfide is accelerated by the formation of iron sulfide minerals that stimulate the cathodic reaction. 

Figure 18.2 Summary of respiratory energy flows. Foods ate converted into the reduced form of nicotinamide adenine dinucleotide (NADH), a strong reductant, which is the most reducing of the respiratory electron carriers (donors). Respiration can he based on a variety of terminal oxidants, such as O2, nitrate, or fumarate. Of those, O2 is the strongest, so that aerobic respiration extracts the largest amount of free energy from a given amount of food. In aerobic respiration, NADH is not oxidized directly by O2 rather, the reaction proceeds through intermediate electron carriers, such as the quinone/quinol couple and cytochrome c. The most efficient respiratory pathway is based on oxidation of ferrocytochrome c (Fe ) with O2 catalyzed by cytochrome c oxidase (CcO). Of the 550 mV difference between the standard potentials of c)Tochrome c and O2, CcO converts 450 mV into proton-motive force (see the text for further details).

At least from the time of van Helmont on, the chemists when separating and describing gases usually examined the effect of the gases on animals and plants. Lavoisier (1777) understood that aerobic respiration is the process in which oxygen is consumed and carbon dioxide is produced, shortly after the discovery of oxygen (1771). However, it took about half a century to make aerobic respiration more comprehensible from a physical point of view (Joule 1843 Mayer 1845 and many others). 

Depth profiles of (a) salinity (%o), (b) dissolved oxygen (ml /L), and (c) percent saturation of dissolved oxygen in the Southeastern Atlantic Ocean (9°30 W 11°20 S). Samples were collected in March 1994. Dotted lines represent the curves generated by the one-dimensional advection-diffusion model (see text for details). The values of Dz, Vz, and J are the ones that best fit the data. Data are from Java Ocean Atlas (http /odf.ucsd.edu/joa). Values of percent saturation of oxygen less than 100 reflect the effects of aerobic respiration. Values greater than 100 indicate a net input, such as from photosynthesis. (See companion website for color version.)... 

The balance between relative rates of aerobic respiration and water movement were considered in Section 4.3.4. We saw that a subsurfece concentration minimum, the oxygen minimum zone (OMZ), is a common characteristic of vertical profiles of dissolved oxygen and is produced by in situ respiration. Waters with O2 concentrations less than 2.0 ppm are termed hypoxic The term anoxic is applied to conditions when O2 is absent. (Some oceanographers use the term suboxic to refer to conditions where O2 concentrations fall below 0.2 ppm but are still detectable.) As illustrated by Figure 4.21b, this water column is hypoxic in the OMZ. The dissolved oxygen concentrations are presented as % saturations in Figure 4.21c. With the exception of the mixed layer, the water column is undersaturated with respect to dissolved oxygen with the most intense undersaturations present in mid-depths. Surface supersaturations are the result of O2 input from photosynthesis and bubble injection. 

Equation 8.4 predicts that aerobic respiration should release dissolved inorganic nitrogen and phosphorus into seawater in the same ratio that is present in plankton, i.e., 16 1. As shown in Figure 8.3, a plot of nitrate versus phosphate for seawater taken from all depths through all the ocean basins has a slope close to 16 1. Why do both plankton and seawater have an N-to-P ratio of 16 1 Does the ratio in seawater determine the ratio in the plankton or vice versa Current thinking is that the N-to-P ratio of seawater reflects a quasi steady state that has been established and stabilized by the collective impacts of several biological processes controlled by marine plankton. 

The dissolved oxygen data follow depth trends that are nearly a mirror image of the nutrients. The OMZ lies at depths slightly above the core of the AAIW. Why is the OMZ located at these depths To answer this question, oceanographers use the vertical concentration profiles of O2, nutrients, and TDIC to assess the relative rates of aerobic respiration and photosynthesis as a function of depth. (The TDIC concentration is used as a measure of how much CO2 has been taken up from or released into the water.)... 

Deviations from the Redfield-Richards ratio can also be caused by remineralization that proceeds by processes other than aerobic respiration. As shown in Figure 10.6, water samples obtained from depths where denitrification has occurred have lower dissolved inorganic nitrogen concentrations ([NOj ] + [NOH) than would be predicted from their AOU. During denitrification, nitrate is first reduced to nitrite and then to N2,... 

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