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Volume 18. Methods of Cell Separation
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Permissions Icon Permissions. Article PDF first page preview. Issue Section:. You do not currently have access to this article. Download all figures. Different tactics have evolved in different animals, depending on the animals' needs. Unicellular organisms simply release the ammonia into the environment. Likewise, bony fish can release the ammonia into the water where it is quickly diluted. In general, mammals convert the ammonia into urea, via the urea cycle.
Journal of Prenatal Medicine - Vol. 11 (No. ) Abstract
In order to determine whether two proteins are related, or in other words to decide whether they are homologous or not, scientists use sequence-comparison methods. Methods like sequence alignments and structural alignments are powerful tools that help scientists identify homologies between related molecules. By finding how similar two protein sequences are, we acquire knowledge about their structure and therefore their function.
Nucleic acids , so called because of their prevalence in cellular nuclei , is the generic name of the family of biopolymers. They are complex, high-molecular-weight biochemical macromolecules that can convey genetic information in all living cells and viruses. The most common nitrogenous bases are adenine , cytosine , guanine , thymine , and uracil. The nitrogenous bases of each strand of a nucleic acid will form hydrogen bonds with certain other nitrogenous bases in a complementary strand of nucleic acid similar to a zipper.
Adenine binds with thymine and uracil; thymine binds only with adenine; and cytosine and guanine can bind only with one another. Aside from the genetic material of the cell, nucleic acids often play a role as second messengers , as well as forming the base molecule for adenosine triphosphate ATP , the primary energy-carrier molecule found in all living organisms. Glucose is an energy source in most life forms.
For instance, polysaccharides are broken down into their monomers by enzymes glycogen phosphorylase removes glucose residues from glycogen, a polysaccharide. Disaccharides like lactose or sucrose are cleaved into their two component monosaccharides. Glucose is mainly metabolized by a very important ten-step pathway called glycolysis , the net result of which is to break down one molecule of glucose into two molecules of pyruvate.
This does not require oxygen; if no oxygen is available or the cell cannot use oxygen , the NAD is restored by converting the pyruvate to lactate lactic acid e.
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Other monosaccharides like galactose and fructose can be converted into intermediates of the glycolytic pathway. In aerobic cells with sufficient oxygen, as in most human cells, the pyruvate is further metabolized. It is irreversibly converted to acetyl-CoA , giving off one carbon atom as the waste product carbon dioxide , generating another reducing equivalent as NADH. The two molecules acetyl-CoA from one molecule of glucose then enter the citric acid cycle , producing two molecules of ATP, six more NADH molecules and two reduced ubi quinones via FADH 2 as enzyme-bound cofactor , and releasing the remaining carbon atoms as carbon dioxide.
The produced NADH and quinol molecules then feed into the enzyme complexes of the respiratory chain, an electron transport system transferring the electrons ultimately to oxygen and conserving the released energy in the form of a proton gradient over a membrane inner mitochondrial membrane in eukaryotes.
This is why humans breathe in oxygen and breathe out carbon dioxide. In vertebrates , vigorously contracting skeletal muscles during weightlifting or sprinting, for example do not receive enough oxygen to meet the energy demand, and so they shift to anaerobic metabolism , converting glucose to lactate. The liver regenerates the glucose, using a process called gluconeogenesis. This process is not quite the opposite of glycolysis, and actually requires three times the amount of energy gained from glycolysis six molecules of ATP are used, compared to the two gained in glycolysis.
Analogous to the above reactions, the glucose produced can then undergo glycolysis in tissues that need energy, be stored as glycogen or starch in plants , or be converted to other monosaccharides or joined into di- or oligosaccharides. The combined pathways of glycolysis during exercise, lactate's crossing via the bloodstream to the liver, subsequent gluconeogenesis and release of glucose into the bloodstream is called the Cori cycle.
Researchers in biochemistry use specific techniques native to biochemistry, but increasingly combine these with techniques and ideas developed in the fields of genetics , molecular biology and biophysics. There is not a defined line between these disciplines. Biochemistry studies the chemistry required for biological activity of molecules, molecular biology studies their biological activity, genetics studies their heredity, which happens to be carried by their genome. This is shown in the following schematic that depicts one possible view of the relationships between the fields: .
Extremophiles are microorganisms which live in extreme conditions, some of which may provide some exceptions or variations on some of the natural laws cited above.
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For example, in July , a scientific study of Kidd Mine in Canada discovered sulfur-breathing organisms which live feet below the surface, and which breathe sulfur in order to survive. Glucose and sucrose are also found in varying quantities in various fruits, and sometimes exceed the fructose present. However, peaches contain more sucrose 6.
From Wikipedia, the free encyclopedia. For the journals, see Biochemistry journal and Biological Chemistry journal. Index Outline. Main article: History of biochemistry.
Main articles: Composition of the human body and Dietary mineral. Main article: Biomolecule. Main articles: Carbohydrate , Monosaccharide , Disaccharide , and Polysaccharide. Glucose, a monosaccharide. Amylose , a polysaccharide made up of several thousand glucose units.
Biochemical analysis - Analytical Chemistry (ACS Publications)
Main articles: Lipid , Glycerol , and Fatty acid. Main articles: Protein and Amino acid. Main article: Carbohydrate metabolism. Main article: Gluconeogenesis. Main article: Outline of biochemistry. Biochemistry portal.
Methods of Biochemical Analysis, Volume 11
Important publications in biochemistry chemistry List of biochemistry topics List of biochemists List of biomolecules. Trends in Biochemical Sciences. Molecular cell biology 4th ed. New York: Scientific American Books. Biochemistry 5th ed. W H Freeman.