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The partial pressure of oxygen in mitochondria is generally assumed to be lower than the surroundings because the mitochondria consume oxygen. [4] If the oxygen level is too low, mitochondria cannot metabolize nutrients for energy via aerobic metabolism. The shift between aerobic and anaerobic metabolism has profound physiological consequences.
RNA folding problem: Is it possible to accurately predict the secondary, tertiary and quaternary structure of a polyribonucleic acid sequence based on its sequence and environment? Protein design : Is it possible to design highly active enzymes de novo for any desired reaction?
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...
Oxygen transmission rate (OTR) is the measurement of the amount of oxygen gas that passes through a substance over a given period. It is mostly carried out on non-porous materials, where the mode of transport is diffusion, but there are a growing number of applications where the transmission rate also depends on flow through apertures of some description.
One example of passive diffusion is the gas exchange that occurs between the oxygen in the blood and the carbon dioxide present in the lungs. [3] Facilitated diffusion is the movement of polar molecules down the concentration gradient with the assistance of membrane proteins .
[3] [5] [7] For example, methanogens grow at a redox potential lower than -0.3 V. [7] Sulfide is an essential component of some enzymes, and molecular oxygen oxidizes this to form disulfide, thus inactivating certain enzymes (e.g. nitrogenase). Organisms may not be able to grow with these essential enzymes deactivated.
A strict but broad definition is an absolute decrease in red blood cell mass, [63] however, a broader definition is a lowered ability of the blood to carry oxygen. [64] An operational definition is a decrease in whole-blood hemoglobin concentration of more than 2 standard deviations below the mean of an age- and sex-matched reference range. [65]
In physiology, respiration is the transport of oxygen from the outside environment to the cells within tissues, and the removal of carbon dioxide in the opposite direction to the environment by a respiratory system. [1]