Misplaced Pages

#589410

52-470: Cytosine was discovered and named by Albrecht Kossel and Albert Neumann in 1894 when it was hydrolyzed from calf thymus tissues. A structure was proposed in 1903, and was synthesized (and thus confirmed) in the laboratory in the same year. In 1998, cytosine was used in an early demonstration of quantum information processing when Oxford University researchers implemented the Deutsch–Jozsa algorithm on

104-508: A nucleotide . As cytidine triphosphate (CTP), it can act as a co-factor to enzymes, and can transfer a phosphate to convert adenosine diphosphate (ADP) to adenosine triphosphate (ATP). In DNA and RNA, cytosine is paired with guanine . However, it is inherently unstable, and can change into uracil ( spontaneous deamination ). This can lead to a point mutation if not repaired by the DNA repair enzymes such as uracil glycosylase, which cleaves

156-416: A purine or pyrimidine nucleobase (sometimes termed nitrogenous base or simply base ), a pentose sugar , and a phosphate group which makes the molecule acidic. The substructure consisting of a nucleobase plus sugar is termed a nucleoside . Nucleic acid types differ in the structure of the sugar in their nucleotides–DNA contains 2'- deoxyribose while RNA contains ribose (where the only difference

208-598: A joint Japan/NASA project, that used novel methods of detection which avoided damaging nucleotides as they were extracted from meteorites. Albrecht Kossel Ludwig Karl Martin Leonhard Albrecht Kossel ( German pronunciation: [ˈalbʁɛçt ˈkɔsl̩] ; 16 September 1853 – 5 July 1927) was a German biochemist and pioneer in the study of genetics . He was awarded the Nobel Prize for Physiology or Medicine in 1910 for his work in determining

260-526: A regular double helix, and can adopt highly complex three-dimensional structures that are based on short stretches of intramolecular base-paired sequences including both Watson-Crick and noncanonical base pairs, and a wide range of complex tertiary interactions. Nucleic acid molecules are usually unbranched and may occur as linear and circular molecules. For example, bacterial chromosomes, plasmids , mitochondrial DNA , and chloroplast DNA are usually circular double-stranded DNA molecules, while chromosomes of

312-403: A two qubit nuclear magnetic resonance quantum computer (NMRQC) . In March 2015, NASA scientists reported the formation of cytosine, along with uracil and thymine, from pyrimidine under the space-like laboratory conditions, which is of interest because pyrimidine has been found in meteorites although its origin is unknown. Cytosine can be found as part of DNA, as part of RNA, or as a part of

364-489: A uracil in DNA. Cytosine can also be methylated into 5-methylcytosine by an enzyme called DNA methyltransferase or be methylated and hydroxylated to make 5-hydroxymethylcytosine . The difference in rates of deamination of cytosine and 5-methylcytosine (to uracil and thymine ) forms the basis of bisulfite sequencing . When found third in a codon of RNA , cytosine is synonymous with uracil , as they are interchangeable as

416-528: Is a single molecule that contains 247 million base pairs ). In most cases, naturally occurring DNA molecules are double-stranded and RNA molecules are single-stranded. There are numerous exceptions, however—some viruses have genomes made of double-stranded RNA and other viruses have single-stranded DNA genomes, and, in some circumstances, nucleic acid structures with three or four strands can form. Nucleic acids are linear polymers (chains) of nucleotides. Each nucleotide consists of three components:

468-409: Is for his work in this respect that the Nobel Prize has been awarded to him this year. Albrecht Kossel is considered one of the great scientists of biochemistry and genetics. By isolating and defining nucleic acid and the nucleobases , he provided the necessary precursors that led to the double-helix model of DNA , devised by James D. Watson and Francis Crick in 1953. " … his elucidation of

520-411: Is one of four types of molecules called nucleobases (informally, bases). It is the sequence of these four nucleobases along the backbone that encodes genetic information. This information specifies the sequence of the amino acids within proteins according to the genetic code . The code is read by copying stretches of DNA into the related nucleic acid RNA in a process called transcription. Within cells, DNA

572-453: Is organized into long sequences called chromosomes. During cell division these chromosomes are duplicated in the process of DNA replication, providing each cell its own complete set of chromosomes. Eukaryotic organisms (animals, plants, fungi, and protists) store most of their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts. In contrast, prokaryotes (bacteria and archaea) store their DNA only in

SECTION 10

#1732869142590

624-561: Is the nucleotide , each of which contains a pentose sugar ( ribose or deoxyribose ), a phosphate group, and a nucleobase . Nucleic acids are also generated within the laboratory, through the use of enzymes (DNA and RNA polymerases) and by solid-phase chemical synthesis . Nucleic acids are generally very large molecules. Indeed, DNA molecules are probably the largest individual molecules known. Well-studied biological nucleic acid molecules range in size from 21 nucleotides ( small interfering RNA ) to large chromosomes ( human chromosome 1

676-477: Is the presence of a hydroxyl group ). Also, the nucleobases found in the two nucleic acid types are different: adenine , cytosine , and guanine are found in both RNA and DNA, while thymine occurs in DNA and uracil occurs in RNA. The sugars and phosphates in nucleic acids are connected to each other in an alternating chain (sugar-phosphate backbone) through phosphodiester linkages. In conventional nomenclature ,

728-575: The Sommerfeld–Kossel displacement law , and other achievements. Albrecht Kossel was apparently not greatly interested in politics, but in 1914 he did not sign the propaganda Pronunciamento of German professors at the start of the war. He suffered under the lies which filled the world in war time. In 1917 Kossel was summoned by the government to pronounce that the allotted food provisions were sufficient. He refused this demand, would never declare untruths as truths Through his marriage to Luise, Kossel

780-454: The University of California at Berkeley , who was also his wife's cousin. He also visited and delivered lectures at several other universities, including the University of Chicago . On the occasion of his visit to New York City, Kossel was interviewed by a reporter from The New York Times . Kossel's English was reportedly very good, and his self-effacing modesty is voluminously mentioned in

832-487: The University of Strassburg to study medicine. He studied under Felix Hoppe-Seyler , who was head of the department of biochemistry, the only such institution in Germany at the time. He attended lectures by Anton de Bary , Waldeyer , August Kundt , and Baeyer . He completed his studies at University of Rostock , and passed his German medical license exam in 1877. After completing his university studies, Kossel returned to

884-426: The University of Tübingen , Germany. He discovered a new substance, which he called nuclein and which - depending on how his results are interpreted in detail - can be seen in modern terms either as a nucleid acid- histone complex or as the actual nucleid acid. Phoeber Aaron Theodor Levene, an American biochemist determined the basic structure of nucleic acids. In the early 1880s, Albrecht Kossel further purified

936-561: The cell nucleus , and for his work in isolating and describing nucleic acids . The award was presented on 10 December 1910. In the autumn of 1911, Kossel was invited to the United States to deliver the Herter Lecture at Johns Hopkins . Traveling with his wife Luise and daughter Gertrude, he took the opportunity to travel and to visit acquaintances, one of which was Eugene W. Hilgard , professor emeritus of agricultural chemistry at

988-660: The monomer components: a 5-carbon sugar , a phosphate group and a nitrogenous base . The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). If the sugar is ribose , the polymer is RNA; if the sugar is deoxyribose , a variant of ribose, the polymer is DNA. Nucleic acids are chemical compounds that are found in nature. They carry information in cells and make up genetic material. These acids are very common in all living things, where they create, encode, and store information in every living cell of every life-form on Earth. In turn, they send and express that information inside and outside

1040-574: The nucleus , and for the presence of phosphate groups (related to phosphoric acid). Although first discovered within the nucleus of eukaryotic cells, nucleic acids are now known to be found in all life forms including within bacteria , archaea , mitochondria , chloroplasts , and viruses (There is debate as to whether viruses are living or non-living ). All living cells contain both DNA and RNA (except some cells such as mature red blood cells), while viruses contain either DNA or RNA, but usually not both. The basic component of biological nucleic acids

1092-507: The polypeptide nature of the protein molecule. The processes of life are like a drama, and I am studying the actors, not the plot. There are many actors, and it is their characters which make this drama. I seek to understand their habits, their peculiarities. Kossel was awarded the Nobel Prize in Physiology or Medicine in 1910 for his research in cell biology , the chemical composition of

SECTION 20

#1732869142590

1144-599: The sequence of nucleotides . Nucleotide sequences are of great importance in biology since they carry the ultimate instructions that encode all biological molecules, molecular assemblies, subcellular and cellular structures, organs, and organisms, and directly enable cognition, memory, and behavior. Enormous efforts have gone into the development of experimental methods to determine the nucleotide sequence of biological DNA and RNA molecules, and today hundreds of millions of nucleotides are sequenced daily at genome centers and smaller laboratories worldwide. In addition to maintaining

1196-687: The Eleventh Physiological Congress in Edinburgh , Scotland. When he appeared before the assembled scientists, they gave him an ovation that lasted several minutes. At the congress, he was conferred an honorary degree by the University of Edinburgh . In 1924, Kossel became professor emeritus , but continued to lecture at Heidelberg University . In April 1927, he attended the Lister Centenary Celebration held in England. During

1248-563: The GenBank nucleic acid sequence database, the National Center for Biotechnology Information (NCBI) provides analysis and retrieval resources for the data in GenBank and other biological data made available through the NCBI web site. Deoxyribonucleic acid (DNA) is a nucleic acid containing the genetic instructions used in the development and functioning of all known living organisms. The chemical DNA

1300-529: The University of Strassburg as research assistant to Felix Hoppe-Seyler. At the time, Hoppe-Seyler was intensely interested in research concerning an acidic substance that had first been chemically isolated from pus cells by one of his former students, Friedrich Miescher , in 1869. Unlike protein, the substance contained considerable amounts of phosphorus , but with its high acidity, it was unlike any cellular substance that had yet been observed. Kossel showed that

1352-520: The carbons to which the phosphate groups attach are the 3'-end and the 5'-end carbons of the sugar. This gives nucleic acids directionality , and the ends of nucleic acid molecules are referred to as 5'-end and 3'-end. The nucleobases are joined to the sugars via an N -glycosidic linkage involving a nucleobase ring nitrogen ( N -1 for pyrimidines and N -9 for purines) and the 1' carbon of the pentose sugar ring. Non-standard nucleosides are also found in both RNA and DNA and usually arise from modification of

1404-446: The cell nucleus. From the inner workings of the cell to the young of a living thing, they contain and provide information via the nucleic acid sequence . This gives the RNA and DNA their unmistakable 'ladder-step' order of nucleotides within their molecules. Both play a crucial role in directing protein synthesis . Strings of nucleotides are bonded to form spiraling backbones and assembled into chains of bases or base-pairs selected from

1456-405: The chemical composition of nucleic acids , the genetic substance of biological cells . Kossel isolated and described the five organic compounds that are present in nucleic acid : adenine , cytosine , guanine , thymine , and uracil . These compounds were later shown to be nucleobases , and are key in the formation of DNA and RNA , the genetic material found in all living cells. Kossel

1508-423: The chemical nature of some building blocks that make up nucleic acids and chromatine has secured immortality for this exeedingly modest and almost shy man." The Albrecht Kossel Institute for Neuroregeneration at the University of Rostock is named in his honor. Nucleic acid Nucleic acids are large biomolecules that are crucial in all cells and viruses. They are composed of nucleotides , which are

1560-621: The cytoplasm. Within the chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed. Ribonucleic acid (RNA) functions in converting genetic information from genes into the amino acid sequences of proteins. The three universal types of RNA include transfer RNA (tRNA), messenger RNA (mRNA), and ribosomal RNA (rRNA). Messenger RNA acts to carry genetic sequence information between DNA and ribosomes, directing protein synthesis and carries instructions from DNA in

1612-584: The discovery of the polypeptide nature of the protein molecule. The Albrecht Kossel Institute for Neuroregeneration at the University of Rostock is named in his honor. Kossel was born in Rostock , Germany as the son of the merchant and Prussian consul Albrecht Karl Ludwig Enoch Kossel and his wife Clara Jeppe Kossel. As a youth, Kossel attended the Gymnasium at Rostock, where he evidenced substantial interest in chemistry and botany. In 1872, Kossel attended

Cytosine - Misplaced Pages Continue

1664-465: The double-helix structure of DNA . Experimental studies of nucleic acids constitute a major part of modern biological and medical research , and form a foundation for genome and forensic science , and the biotechnology and pharmaceutical industries . The term nucleic acid is the overall name for DNA and RNA, members of a family of biopolymers , and is a type of polynucleotide . Nucleic acids were named for their initial discovery within

1716-425: The eukaryotic nucleus are usually linear double-stranded DNA molecules. Most RNA molecules are linear, single-stranded molecules, but both circular and branched molecules can result from RNA splicing reactions. The total amount of pyrimidines in a double-stranded DNA molecule is equal to the total amount of purines. The diameter of the helix is about 20 Å . One DNA or RNA molecule differs from another primarily in

1768-632: The five primary, or canonical, nucleobases . RNA usually forms a chain of single bases, whereas DNA forms a chain of base pairs. The bases found in RNA and DNA are: adenine , cytosine , guanine , thymine , and uracil . Thymine occurs only in DNA and uracil only in RNA. Using amino acids and protein synthesis , the specific sequence in DNA of these nucleobase-pairs helps to keep and send coded instructions as genes . In RNA, base-pair sequencing helps to make new proteins that determine most chemical processes of all life forms. Nucleic acid was, partially, first discovered by Friedrich Miescher in 1869 at

1820-515: The last years of Kossel's life, he conducted important research into the composition of the protein types protamines and histones , and introduced flavianic acid for the quantitative separation of arginine, histidine and lysine in proteins. A monograph describing this work was published shortly after his death. Kossel contributed to early issues of the Zeitschrift für Physiologische Chemie (Journal of Physiological Chemistry). This publication

1872-515: The nucleid acid substance and discovered its highly acidic properties. He later also identified the nucleobases . In 1889 Richard Altmann created the term nucleic acid – at that time DNA and RNA were not differentiated. In 1938 Astbury and Bell published the first X-ray diffraction pattern of DNA. In 1944 the Avery–MacLeod–McCarty experiment showed that DNA is the carrier of genetic information and in 1953 Watson and Crick proposed

1924-515: The nucleus to ribosome . Ribosomal RNA reads the DNA sequence, and catalyzes peptide bond formation. Transfer RNA serves as the carrier molecule for amino acids to be used in protein synthesis, and is responsible for decoding the mRNA. In addition, many other classes of RNA are now known. Artificial nucleic acid analogues have been designed and synthesized. They include peptide nucleic acid , morpholino - and locked nucleic acid , glycol nucleic acid , and threose nucleic acid . Each of these

1976-464: The other hand, remains less understood. Until October 2021, Cytosine had not been found in meteorites, which suggested the first strands of RNA and DNA had to look elsewhere to obtain this building block. Cytosine likely formed within some meteorite parent bodies, however did not persist within these bodies due to an effective deamination reaction into uracil . In October 2021, Cytosine was announced as having been found in meteorites by researchers in

2028-530: The quantitative separation of the "hexone bases" (the alpha-amino acids arginine , histidine , and lysine ). He was also the first to isolate theophylline , a therapeutic drug found naturally in tea and cocoa beans. In 1901, Kossel was named to a similar post at Heidelberg University , and became director of the Heidelberg Institute for Protein Investigation. His research predicted the discovery of

2080-437: The reporter's account. His Herter lecture at Johns Hopkins was titled, "The Proteins". This was the only time Kossel ever visited the United States. With his distinguished English pupil Henry Drysdale Dakin , Kossel investigated arginase , the ferment which hydrolyses arginine into urea and ornithine . Later, he discovered agmatine in herring roe and devised a method for preparing it. Another of Kossel's students

2132-483: The standard nucleosides within the DNA molecule or the primary (initial) RNA transcript. Transfer RNA (tRNA) molecules contain a particularly large number of modified nucleosides. Double-stranded nucleic acids are made up of complementary sequences, in which extensive Watson-Crick base pairing results in a highly repeated and quite uniform nucleic acid double-helical three-dimensional structure. In contrast, single-stranded RNA and DNA molecules are not constrained to

Cytosine - Misplaced Pages Continue

2184-607: The substance, called "nuclein", consisted of a protein component and a non-protein component. Kossel further isolated and described the non-protein component. This substance has become known as nucleic acid , which contains the genetic information found in all living cells. In 1883, Kossel left Strassburg to become Director of the Chemistry Division of the Physiological Institute at the University of Berlin . In this post, he succeeded Eugen Baumann and worked under

2236-452: The supervision of Emil du Bois-Reymond . Kossel continued his previous work on the nucleic acids. During the period 1885 to 1901, he was able to isolate and name its five constituent organic compounds : adenine , cytosine , guanine , thymine , and uracil . These compounds are now known collectively as nucleobases , and they provide the molecular structure necessary in the formation of stable DNA and RNA molecules. In 1895, Kossel

2288-519: The third base. When found as the second base in a codon, the third is always interchangeable. For example, UCU, UCC, UCA and UCG are all serine , regardless of the third base. Active enzymatic deamination of cytosine or 5-methylcytosine by the APOBEC family of cytosine deaminases could have both beneficial and detrimental implications on various cellular processes as well as on organismal evolution. The implications of deamination on 5-hydroxymethylcytosine, on

2340-433: The view that its smallest independent units morphologically speaking – the cells – also to a certain degree lead an independent life and are the real seats of the vital processes. The cells therefore attract special attention in biological research, and studies which widen our knowledge of the cells to any important extent deserve to be given prominence. Prof. Kossel has chosen to devote himself to this field of research, and it

2392-401: Was American biochemist Edwin B. Hart , who would later return to the United States to participate in the " Single-grain experiment " (1907–1911) and be part of research teams that would determine the nutritive causes of anemia and goiter . Another was Otto Folin , an American chemist who discovered Phosphocreatine . In 1923, Kossel was honored by being named Germany's representative to

2444-487: Was also a noted philologist of his day. The couple had three children, two of whom survived to maturity: Walther, born in 1888, and daughter Gertrude, born in 1889. Son Walther Kossel (1888–1956) became a prominent physicist and was professor of theoretical physics and director of the Physics Institute at the University of Tübingen . He is known for his theory of the chemical bond ( ionic bond / octet rule ),

2496-454: Was an important influence on and collaborator with other important researchers in biochemistry, including Henry Drysdale Dakin , Friedrich Miescher , Edwin B. Hart , and his professor and mentor, Felix Hoppe-Seyler . Kossel was editor of the Zeitschrift für Physiologische Chemie (Journal of Physiological Chemistry) from 1895 until his death. Kossel also conducted important research into the composition of protein , and his research predicted

2548-672: Was discovered in 1869, but its role in genetic inheritance was not demonstrated until 1943. The DNA segments that carry this genetic information are called genes. Other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information. Along with RNA and proteins, DNA is one of the three major macromolecules that are essential for all known forms of life. DNA consists of two long polymers of monomer units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds. These two strands are oriented in opposite directions to each other and are, therefore, antiparallel . Attached to each sugar

2600-570: Was founded by his professor and mentor, Felix Hoppe-Seyler , in 1877, the same year that Kossel started work as his research assistant. After Hoppe-Seyler's death in 1895, Kossel took over editorship of the Zeitschrift and continued in that role until his own death in 1927. In 1886, Kossel married Luise Holtzman, daughter of Adolf Holtzmann . Holtzmann was Professor at the University of Heidelberg , lecturing in German literature as well as Sanskrit . He

2652-408: Was professor of physiology as well as director of the Physiological Institute at the University of Marburg . Around this time, he began investigations into the chemical composition of proteins , the alterations in proteins during transformation into peptone , the peptide components of cells, and other investigations. In 1896, Kossel discovered histidine , then worked out the classical method for

SECTION 50

#1732869142590

2704-472: Was related to several prominent Americans, including soil science pioneer Eugene W. Hilgard , journalist and financier Henry Villard , and abolitionist William Lloyd Garrison . Luise Kossel died in 1913 of acute pancreatitis . Kossel died quietly on 5 July 1927, after a recurring attack of angina pectoris . He is buried in Heidelberg , Germany. The study of the living organism has more and more led to

#589410