Biochemistry , sometimes called biological chemistry , is the study of chemical processes in and related to living organisms. By controlling the flow of information through biochemical signaling and the flow of chemical energy through metabolism, biochemical processes give rise to the complexity of life. During the last decades of the 20th century, biochemistry has become very successful in explaining the life processes that now almost all areas of life science from botany to medicine and genetics are involved in biochemical research. Currently, the main focus of pure biochemistry is on understanding how biological molecules induce processes that occur in living cells, which in turn are strongly related to the study and understanding of tissues, organs, and all organisms - that is, all from biology.
Biochemistry is closely related to molecular biology, the study of molecular mechanisms by which the genetic information encoded in DNA is capable of producing life processes. Depending on the exact definition of the term used, molecular biology may be considered a branch of biochemistry, or biochemistry as a tool for investigating and studying molecular biology.
Many biochemicals are related to the structure, function and interaction of biological macromolecules, such as proteins, nucleic acids, carbohydrates and lipids, which provide cell structure and perform many functions related to life. The cell's chemical properties also depend on the reaction of smaller molecules and ions. These can be inorganic, eg water and metal ions, or organic, eg amino acids, which are used to synthesize proteins. The mechanism by which cells utilize energy from their environment through a chemical reaction known as metabolism. Biochemical findings are applied primarily in medicine, nutrition, and agriculture. In the medical world, biochemists investigate the causes and cures of diseases. In nutrition, they learn how to maintain health and learn the effects of nutritional deficiencies. In agriculture, biochemists investigate soil and fertilizers, and try to find ways to improve crop cultivation, plant storage and pest control.
Video Biochemistry
History
In its broadest definition, biochemistry can be seen as the study of the components and composition of living things and how they unite to become alive, in this sense the biochemical history can return as far back as the ancient Greeks. However, biochemistry as a particular discipline had its beginnings in the 19th century, or slightly earlier, depending on which aspects of the biochemistry were being focused. Some argue that early biochemistry may have been the discovery of the first enzyme, diastase (today called amylase), in 1833 by Anselme Payen, while others consider the first demonstration of Eduard Buchner's biochemical process of complex alcoholic fermentation in cell-free extract in 1897 to biochemical birth. Some may also point out as the beginning for influential 1842 works by Justus von Liebig, Animal chemistry, or, Organic Chemistry in its application to physiology and pathology, presenting metabolic chemical theory, or even earlier. for the study of the 18th century on fermentation and respiration by Antoine Lavoisier. Many other pioneers in the field that help uncover layers of biochemical complexity have been declared the founders of modern biochemistry, such as Emil Fischer for his work on protein chemistry, and F. Gowland Hopkins on enzymes and dynamic biochemical properties.
The term "biochemistry" itself comes from a combination of biology and chemistry. In 1877, Felix Hoppe-Seyler used the term ( biochemie in German) as a synonym for physiological chemistry in the preface for the first edition of Zeitschrift fÃÆ'¼r Physiologische Chemie (Journal of Chemical Physiology) in which he contends for the establishment of an institution dedicated to this field of study. However, the German chemist Carl Neuberg was often quoted to create the word in 1903, while some were credited to Franz Hofmeister.
It was once believed that life and material possessed several essential properties or substances (often referred to as "vital principles") that differed from those found in inanimate matter, and were thought to be only living things that could produce life molecules. Then, in 1828, Friedrich WÃÆ'¶hler published a paper on urea synthesis, proving that organic compounds can be made artificially. Since then, biochemistry has advanced, especially since the mid-20th century, with the development of new techniques such as chromatography, X-ray diffraction, dual polarization interferometry, NMR spectroscopy, radioisotope labeling, electron microscopy, and molecular dynamics simulations. These techniques allow for the discovery and detailed analysis of many molecules and pathways of cell metabolism, such as glycolysis and the Krebs cycle (citric acid cycle), and lead to a biochemical understanding at the molecular level.
Another important historic event in biochemistry is the discovery of genes and their role in the transfer of information within cells. This biochemical part is often called molecular biology. In the 1950s, James D. Watson, Francis Crick, Rosalind Franklin, and Maurice Wilkins were instrumental in breaking the structure of DNA and suggesting its relationship to the genetic transfer of information. In 1958, George Beadle and Edward Tatum received the Nobel Prize for working in mushrooms that showed that one gene produced one enzyme. In 1988, Colin Pitchfork was the first person convicted of murder with DNA evidence, leading to the growth of forensic science. Recently, Andrew Z. Fire and Craig C. Mello received the 2006 Nobel Prize to discover the role of RNA interference (RNAi), in silencing gene expression.
Maps Biochemistry
Initial material: chemical elements of life
Only six elements - carbon, hydrogen, nitrogen, oxygen, calcium, and phosphorus - form nearly 99% of the mass of living cells, including those in the human body (see composition of the human body for a complete list). In addition to the six main elements that make up the bulk of the human body, humans require smaller numbers of possibilities of 18 more.
Biomolecules
The four major classes of molecules in biochemistry (often called biomolecules) are carbohydrates, lipids, proteins, and nucleic acids. Many biological molecules are polymers: in this terminology, monomers are relatively small micromolecules that are linked together to create large macromolecules known as polymers. When the monomers are linked together to synthesize biological polymers, they undergo a process called dehydration synthesis. Different macromolecules can converge in larger complexes, often required for biological activity.
Carbohydrates
Carbohydrate functions include energy storage and provide structure. Sugars are carbohydrates, but not all carbohydrates are sugars. There are more carbohydrates on Earth than any other known biomolecule; they are used to store energy and genetic information, and play an important role in cell interaction and cell communication.
The simplest type of carbohydrate is the monosaccharide, which among other properties contains carbon, hydrogen, and oxygen, largely in the ratio of 1: 2: 1 (general formula C n > H 2 n , where n at least 3). Glucose (C 6 H 12 6 ) is one of the most important carbohydrates; others include fructose (C 6 H 12 6 ), sugar is generally associated with sweetness of fruit, and deoxyribose (C 5 H 10 O 4 ). Monosaccharides may alternate between the acyclic (open chain) and cyclic forms. The open chain form can be converted into a ring of carbon atoms that are bridged by an oxygen atom made from one end carbonyl group and another hydroxyl group. Cyclic molecules have hemiketal or hemiketal groups, depending on whether the linear form is aldose or ketose.
In this cyclic form, the ring usually has atoms 5 or 6 . These forms are called furanoses and pyranoses, respectively - by analogy with furan and pyran, the simplest compounds with the same carbon-oxygen rings (though they do not have double bonds of these two molecules). For example, aldohexose glucose can form a hemiacetal relationship between hydroxyl in carbon 1 and oxygen in carbon 4, producing a molecule with a 5-membered ring, called glucofuranose. The same reaction can occur between carbon 1 and 5 to form a molecule with a 6-membered ring, called glucopyranose. A cyclic shape with a 7-atom ring called heptosis is rare.
Two monosaccharides can be incorporated by the glycosidic or ether bonds into disaccharides through the dehydration reaction as long as the water molecule is released. The reverse reaction in which the glycosidic bond of the disaccharide is broken down into two monosaccharides is called hydrolysis . The most famous disaccharides are sucrose or ordinary sugar, which consists of glucose molecules and fructose molecules joined together. Another important disaccharide is lactose found in milk, which consists of glucose molecules and galactose molecules. Lactose can be hydrolysed by lactase, and deficiency in this enzyme produces lactose intolerance.
When some (about three to six) monosaccharides join, it is called oligosaccharide ( oligo - meaning "little"). These molecules tend to be used as markers and signals, and have several other uses. Many monosaccharides join together making polysaccharides. They can join together in a long linear chain, or they can branch off. The two most common polysaccharides are cellulose and glycogen, both of which consist of repeating glucose monomers. An example is cellulose , which is an important structural component of plant cell walls, and glycogen , used as a form of energy storage in animals.
Sugar can be characterized by having a reduction or reduction of the tip. A carbohydrate reduction is a carbon atom that can be in equilibrium with an open chain aldehyde (aldose) or a keto (ketose) form. If the monomer incorporation occurs in such carbon atoms, the free hydroxic group of pyranose or furanose forms is exchanged with the OH side chain of another sugar, giving full acetal. This prevents chain opening to aldehyde or keto form and makes the modified residue does not reduce. Lactose contains a reducing tip in the glucose section, while the galactose part forms an acetal full of C4-OH glucose groups. Saccharose has no final reduction due to full asset formation between carbon glucose aldehyde (C1) and carbon keto fructose (C2).
Lipid
Lipids are composed of various molecules and to some extent are catches for compounds that are relatively insoluble in water or nonpolar biological origin, including waxes, fatty acids, phospholipids derived from fatty acids, sphingolipids, glycolipids and terpenoids (for example, retinoids and steroids). Some lipids are linear aliphatic molecules, while others have ring structures. Some are aromatic, while others are not. Some are flexible, while others are rigid.
Lipids are usually made of one molecule of glycerol in combination with another molecule. In triglycerides, the main group of mass lipids, there is one molecule of glycerol and three fatty acids. Fatty acids are considered monomers in this case, and may be saturated (no double bonds in the carbon chain) or unsaturated (one or more double bonds in the carbon chain).
Most of the lipids have some polar characters in addition to most nonpolar. In general, most of the structure is nonpolar or hydrophobic ("fear of water"), which means that it does not interact well with polar solvents like water. The other part of their structure is polar or hydrophilic ("loving water") and will tend to associate with polar solvents like water. This makes them amphiphilic molecules (having both hydrophobic and hydrophilic parts). In the case of cholesterol, the polar group is only -OH (hydroxyl or alcohol). In the case of phospholipids, polar groups are much larger and more polar, as described below.
Lipids are an integral part of our daily diet. Most of the oils and dairy products we use for cooking and eating such as butter, cheese, ghee etc., consist of fat. Vegetable oils are rich in various polyunsaturated fatty acids (PUFAs). Foods that contain lipids undergo digestion in the body and are broken down into fatty acids and glycerol, which are the final degradation products of fat and lipids. Lipids, especially phospholipids, are also used in various pharmaceutical products, either as co-solubilisers (for example, in parenteral infusions) or else as drug carrier components (eg, in liposomes or transferometers).
Protein
Proteins are very large molecules - macro-biopolymers - made of monomers called amino acids. Amino acids consist of carbon atoms attached to amino groups, --NH 2 , a carboxylic acid group, --COOH (although these exist as --NH 3 and --COO - under physiological conditions), simple hydrogen atoms, and side chains commonly denoted as "--R". The "R" side chains are different for each of the 20 standard amino acids. It is the "R" group that makes each amino acid different, and the side chain properties greatly affect the overall three-dimensional conformation of the protein. Some amino acids have their own functions or in modified form; for example, the function of glutamate as an important neurotransmitter. Amino acids can be joined by peptide bonds. In this dehydration synthesis, water molecules are removed and peptide bonds connect nitrogen from one amino group of amino acids to carbon from another carboxylic acid group. The resulting molecule is called dipeptide , and the short stretch of the amino acid (usually, less than thirty) is called the
Proteins can have structural and/or functional roles. For example, movements of actin and myosin proteins are ultimately responsible for skeletal muscle contractions. One property that many proteins possess is that they specifically bind molecules or specific molecular classes - they may be very selective in what they bind. Antibodies are examples of proteins that are attached to one particular type of molecule. Antibodies consist of heavy and light chains. Two heavy chains will be connected with two light chains through the disulfide link between their amino acids. Antibodies are specific through variations based on differences in N-terminal domains.
In fact, enzyme-linked immunosorbent assays (ELISAs), which use antibodies, are among the most sensitive tests used by modern medicine to detect a variety of biomolecules. Perhaps the most important protein, however, is the enzyme. Almost every reaction in a living cell requires an enzyme to decrease the activation energy of the reaction. These molecules recognize certain reactant molecules called substrates ; they then catalyze the reaction between them. By lowering the activation energy, the enzyme accelerates the reaction at a rate of 10 11 or more; a reaction that usually takes more than 3,000 years to complete spontaneously may take less than a second with the enzyme. The enzyme itself is not used in the process, and is free to catalyze the same reaction with a new substrate set. By using various modifiers, enzyme activity can be regulated, enabling overall cell biochemical control.
The protein structure is traditionally described in a four level hierarchy. The main structure of a protein consists only of a linear sequence of amino acids; for example, "alanine-glycine-tryptophan-serine-glutamate-asparagine-glycine-lysine -...". Secondary structures relate to local morphology (morphology into structural studies). Some amino acid combinations will tend to be curled up in a coil called "- almost or into a sheet called" - sheet; some? - can be seen in the hemoglobin scheme above. Tertiary structures are all three-dimensional shapes of proteins. This shape is determined by the amino acid sequence. In fact, a change can change the whole structure. The alpha chains of hemoglobin contain 146 amino acid residues; substitution of glutamate residues at position 6 with valine residues alters the behavior of hemoglobin thus causing sickle cell disease. Finally, quaternary structures are related to protein structures with several peptide subunits, such as hemoglobin with its four subunits. Not all proteins have more than one subunit.
The swallowed protein is usually broken down into a single amino acid or dipeptide in the small intestine, and then absorbed. They can then join to create a new protein. The glycolytic intermediate product, the citric acid cycle, and the pentose phosphate line can be used to make all twenty amino acids, and most bacteria and plants have all the enzymes necessary to synthesize them. Humans and other mammals, however, can synthesize only half of them. They can not synthesize isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. It is an essential amino acid, because it is very important to swallow it. Mammals do have enzymes to synthesize alanine, asparagin, aspartate, cysteine, glutamate, glutamine, glycine, proline, serine, and tyrosine, a nonessential amino acid. Although they can synthesize arginine and histidine, they can not produce it in sufficient quantities for growing young animals, and as such it is often regarded as an essential amino acid.
If the amino group is removed from the amino acid, it leaves behind a carbon skeleton called acid-net. An enzyme called transaminase can easily transfer amino groups from one amino acid (making it 'acid-net') to another? -keto acid (make it an amino acid). This is important in the biosynthesis of amino acids, since many pathways, intermediates of other biochemical pathways are converted to a net-acid template, and then amino groups are added, often via transamination. Amino acids can then be linked together to make proteins.
A similar process is used to break down proteins. It is first hydrolyzed into amino acid components. Free ammonia (NH 3 ), which exists as an ammonium ion (NH 4 ) in blood, is toxic to life forms. Appropriate methods for excretion should be present. Different tactics have evolved in different animals, depending on the needs of the animals. Unicellular organisms only release ammonia to the environment. Likewise, bony fish can release ammonia into water that is rapidly diluted. In general, mammals convert ammonia into urea, through the urea cycle.
To determine whether two proteins are related, or in other words to decide whether they are homologous or not, scientists use a sequence-comparison method. Methods such as sequential alignments and structural alignments are powerful tools that help scientists identify homology between related molecules. The relevance of finding homology among proteins extends beyond the evolutionary formation of protein families. By discovering how these two sequences of proteins are similar, we gain knowledge of their structure and therefore their function.
Nucleic acid
Nucleic acid, so called because of their prevalence in the cell nucleus, is the generic name of the biopolymer family. They are high molecular weight and complex biochemical macromolecules that can convey genetic information in all living cells and viruses. Monomers are called nucleotides, and each consists of three components: a heterocyclic base of nitrogen (either purine or pyrimidine), pentose sugar, and a phosphate group.
The most common nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Groups of phosphates and sugars from nucleotide bonds to each other to form the backbone of nucleic acids, while the sequence of nitrogen bases stores information. The most common nitrogen bases are adenine, cytosine, guanine, thymine, and uracil. The nitrogen base of each strand of nucleic acid will form a hydrogen bond with a certain other nitrogen base in a complementary strand of nucleic acid (similar to a zipper). Adenine binds to thymine and uracil; thymine binds only with adenine; and cytosine and guanine can only bind to each other.
Apart from cell genetic material, nucleic acid often acts as the second messenger, and forms the basic molecule for adenosine triphosphate (ATP), the major energy-carrying molecule found in all living organisms. Also, possible nitrogenous bases in two different nucleic acids: adenine, cytosine, and guanine occur in RNA and DNA, whereas thymine occurs only in DNA and uracil occurs in RNA.
Metabolism
Carbohydrates as an energy source
Glucose is the source of energy in most life forms. For example, the polysaccharide is broken down into its monomers (glycogen phosphorylase removes glucose residues from glycogen). Disaccharides such as lactose or sucrose are split into two monosaccharide components.
Glycolysis (anaerobic)
Glucose is primarily metabolized by a very important ten-step path called glycolysis, the net result is to break one molecule of glucose into two pyruvate molecules. It also produces two clean ATP molecules, the energy currency of the cell, together with two equivalents of NAD conversion (adenine nicotinamide nucleotide: oxidized form) to NADH (nicotinamide adenine dinucleotide: reduced form). It does not require oxygen; if no oxygen is available (or cells can not use oxygen), NAD is recovered by converting pyruvate to lactate (lactic acid) (eg, in humans) or ethanol plus carbon dioxide (eg, in yeast). Other monosaccharides such as galactose and fructose can be converted into intermediates of the glycolytic pathway.
Aerobics
In aerobic cells with sufficient oxygen, as in most human cells, pyruvate is further metabolized. It is converted to acetyl-CoA, producing one carbon atom as a carbon dioxide waste product, resulting in a reduction equivalent to NADH. Two molecules of acetyl-CoA (from one glucose molecule) then enter the citric acid cycle, yielding two more ATP molecules, six NADH molecules and two quinones derived (via FADH 2 as cofactors bound to the enzyme ), and releases the remaining carbon atoms as carbon dioxide. The resulting NADH and quinol molecules are then fed into the enzyme complexes of the respiratory chain, the electron transport system transfers the electrons to oxygen and conserves the energy released in the form of a proton gradient over the membrane (mitochondrial membrane in eukaryotes). Thus, the oxygen is reduced to water and the original electron acceptor NAD and the quinone is regenerated. This is why humans inhale oxygen and inhale carbon dioxide. The energy released from transferring electrons from high-energy states in NADH and quinol is first preserved as a proton gradient and converted to ATP through ATP synthase. This results in an additional 28 ATP molecules (24 of 8 NADH 4 of 2 quinols), 32 conserved ATP molecules per degraded glucose (two of the two glycolysis of the citrate cycle). It is clear that using oxygen to fully oxidize glucose provides an organism with much greater energy than the oxygen-free metabolism features, and this is considered the reason why complex life emerges only after Earth's atmosphere accumulates a large amount of oxygen.
Gluconeogenesis
In vertebrates, fully squeezed skeletal muscles (during lifting weights or running fast, for example) do not receive enough oxygen to meet energy demand, so they switch to anaerobic metabolism, converting glucose into lactate. The liver regenerates glucose, using a process called gluconeogenesis. This process is not opposed to glycolysis, and actually requires three times the amount of energy obtained from glycolysis (six ATP molecules are used, compared to two obtained in glycolysis). Similar to the above reaction, the resulting glucose can then undergo glycolysis in energy-consuming tissues, stored as glycogen (or starch in plants), or converted to other monosaccharides or into inner or oligosaccharides. The combined pathway of glycolysis during exercise, lactate crossing through the bloodstream to the liver, subsequent gluconeogenesis and the release of glucose into the bloodstream is called the Cori cycle.
Links to other "molecular-scale" biological sciences
Researchers in biochemistry use special techniques that are original to biochemistry, but increasingly combine these with techniques and ideas developed in the fields of genetics, molecular biology and biophysics. There has never been a hard line between these disciplines in terms of content and techniques. Today, the terms molecular biology and biochemistry are almost interchangeable. The following figure is a scheme that illustrates a possible display of relationships between fields:
- Biochemistry is the study of chemicals and vital processes that occur in living organisms. Biochemists focus heavily on the role, function, and structure of biomolecules. The study of the chemistry behind biological processes and the synthesis of biologically active molecules is a biochemical example.
- Genetics is the study of the effect of genetic differences on organisms. Often this can be inferred by the absence of a normal component (eg, a gene), in a study of "mutants" - organisms with altered genes that lead to different organisms in connection with so-called "wild type" or normal phenotypes. Genetic interactions (epistasis) can often obscure simple interpretations of "knock-out" or "knock-in" studies.
- molecular biology is the study of the molecular foundations of the process of replication, transcription and translation of the genetic material. The central dogma of molecular biology in which genetic material is transcribed into RNA and then translated into proteins, although the simplified molecular biology picture, still provides a good starting point for understanding the field. This image, however, is undergoing a revision in connection with the emergence of a new role for RNA.
- Chemical biology is trying to develop new tools based on small molecules that allow minimal disturbance of biological systems while providing detailed information about their function. Furthermore, chemical biology uses biological systems to create non-natural hybrids between biomolecules and synthetic devices (eg, empty viral capsules that can provide gene therapy or drug molecules).
See also
List
See also
Note
References
Literature quoted
Further reading
External links
- "Biochemical Society".
- Virtual Library of Biochemistry, Molecular Biology, and Cell Biology
- Biochemistry, 5th ed. The full text of Berg, Tymoczko, and Stryer, belongs to NCBI.
- SystemsX.ch - The Swiss Initiative in Biological Systems
- The full text of Biochemistry by Kevin and Indira, an introductory biochemical book.
Source of the article : Wikipedia
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