Nama : Silfia Emilda Dasmir
NIM : RRA1C109001
Nucleic Acid Structure
Nucleic Acid (English: nucleic acid) is a complex biochemical macromolecules, high molecular weight, and composed of nucleotide chains that play a role in the storage and transfer of genetic information (polinukleotida).
1. Primary Structure
Genetic information that exist on the primary structure, are :
2. Secondary Structure
Double helix
- Watson n Crick answer the 3D structure of DNA with the X-ray Diffraction pattern: HSL research Rosalind Franklin.
Able to conclude that:
- has a double helix structure
- with 10 bases eachu round
- 360 ° rotation,
- A-T, G -uNitrogen base C
- notch major and minor
- double helix twist to theu right
- selfu replication
Picture. 1. 1. Nucleic Acid Structure
Type Nucleotide :
-The name depends on basanya
-The number of phosphate-owned
Adenine = AMP, ADP, ATP, damp, dADP, dATP
Guanine = GMP, GDP, GTP, dGMP, dGDP, dGTP
Cytosine = CMP, CDP, CTP, dCTP, dCDP, dCTP
Thymine = TMP, TDP, TTP, -
Uracil = UMP, UDP, UTP, dump, dUDP, dUTP
Table. 1.1. Abbreviations Names Nucleotide
The most common nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Nucleic acid found in all living cells and the virus.
Picture. 1. 2. DNA and RNA
Nucleic acids so named because the existence of generally in the core (nucleus) of cells. In eukaryotic cells, DNA present in the nucleus, while prokaryotic cells, found in the cytoplasm or nukleoid and serves as the molecule of heredity or inheritance. Nucleic acid is a biopolymer, and the constituent monomers are nucleotides. Each nucleotide consists of three components, namely a nitrogen heterocyclic base (purine or pyrimidine), a pentose sugar and a phosphate group. Purine base has two rings (bicyclic), whereas the pyrimidine base has only one ring (monocyclic). Types of nucleic acids are distinguished by the type of sugar found in nucleic acid chain (eg, DNA or deoxyribonucleic acid contains 2-deoxyribose).
Picture. 1. 3. Authors Nucleotides Nucleic Acid Structure
In addition, the nitrogen bases found in both types of nucleic acids have different: adenine, cytosine, and guanine can be found in RNA or DNA, while thymine is found only in DNA and uracil can be found only in RNA. Thymine uracil differ only because of the methyl group at position number 5 so that thymine can also be said as a 5-metilurasil. Among the three components of nucleic acid monomers mentioned above, only the N-base that allows the occurrence of variations.
An understanding of nucleic acids are useful in understanding the underlying biochemistry, especially in terms of genetics. Nucleic acids are composed of more than one nucleotide. Nucleotides are the ester bond between nekleosida with phosphate.
While the nucleoside itself is a bond of beta-N-glycosidic, where the purine and pyrimidine have sugars with nitrogen bond. In other words nucleoside is a nucleotide that is not terphosporilasi (not bind to phosphate). In general, the nucleoside is a bond between the sugar and nitrogen base. In the ADP and ATP binds to the phosphate bond mutual Anhydride acid.
Table. 1.2. The names of nucleoside
Sugar is divided into two types namely ribonukloesida and dioksi ribonukleosida. In ribonukleosida, nitrogen bond occurs in the D-ribose, whereas in dioksiribonukleosida, N bond in 2-deoxy-D-ribose.
Nitrogenous bases in nucleic acids composed of kinds of purine bases and pyrimidine bases. Purine bases adenine and guanine have. While the pyrimidine base has cytosine, thymine (in DNA), and uracil (in RNA).
Picture.1.4. Purine and pyrimidine bases and structure implies
DNA
DNA is a polymer which consists of three main components: a phosphate group, deoxyribose sugar, and nitrogenous bases. A monomer units of DNA that consists of three components called nucleotides, so that DNA classified as polinukleotida.
DNA chain has a width of 22-24 Å, while the length of one nucleotide unit of 3.3 Å [1]. Although the monomer unit is very small, DNA can have millions of nucleotides strung like a chain. For example, the largest chromosome in humans consists of 220 million nucleotides.
Main frame consists of strands of DNA phosphate groups and sugars that criss-cross. Sugar in DNA is the sugar pentose (five-carbon), which is 2-deoxyribose. Two groups of sugar to connect with phosphate via a phosphodiester bond between the three carbon atoms on the ring carbon atoms of sugar and one fifth in the other sugar. One major difference of DNA and RNA is the sugar constituent; sugar of RNA is ribose.
DNA consists of two twisted strands that form a double helix structure. In the double helix structure, orientation of chains of nucleotides on one strand opposite the orientation of the other strand of nucleotides. This is referred to as antiparallel. Each strand consists of the main frame, as the main structure, and nitrogen bases, which interact with DNA strands only in the helix. Both strands of the DNA double helix held together by hydrogen bonds between bases located on the second strand. The four bases found in DNA are adenine (dilambangkan A), cytosine (C, of cytosine), guanine (G), and thymine (T). Adenine hydrogen bond with thymine, while guanine binds to cytosine.
1. The structure of spiral staircase (double helix) DNA
Two scientists, JDWatson and FHCCrick, proposed model of the molecular structure of DNA, which until now was believed to be the truth and made the basis in a variety of techniques related to DNA manipulation. The model is known as berplilin ladder (double helix). By nature of DNA in general have a molecular structure of this spiral staircase.
Spiral staircase model describing the molecular structure of DNA as two mutually polinukleotida chain entwine to form a spiral with the spiral to the right. Phosphate and sugar in their respective chains facing outward torsion axis, whereas the N-base facing toward the axis of torsion with a very unique arrangement as a pair - base pairs between the two chains. In this case, the base A on one chain will be paired with the base T at other chains, whereas the G base pairs with base C. These base pairs are linked by weak hydrogen bonds (nonkovalen). Bases A and T are linked by double hydrogen bonds, while G and C bases are connected by triple hydrogen bonds. The existence of these hydrogen bonds makes the two chains polinukleotida bound to one another and mutually complementary. That is, once a base sequence in one chain is known, then the sequence on the other chain can be determined.
Therefore bicyclic bases are always paired with a monocyclic base, then the distance between the two chains polinukleotida along the DNA molecule will always remain. In other words, the two chains are parallel. However, if the chain is one way to read from 5 'to 3', then the partner chain is read from the direction 3 'to 5'. Thus, the two chains are parallel but opposite directions (antiparallel).
RNA
Ribonucleic acid (English: ribonucleic acid, RNA), a compound that is the genetic material and plays a major role in genetic expression. The principal dogma (central dogma) of molecular genetics, RNA mediates between the information carried DNA and phenotypic expression in the form of the protein.
RNA there are 5 kinds:
1. hnRNA : -heterogeonous nuclear RNA is a direct result of DNA transcription
2. mRNA : -posttranskripsi has undergone a process of eliminating introns
-genetic information in the form of codon (sequence of three nucleotides)
3. rRNA ribosome Komponen where translation progress.
4. tRNA : -Menerjemahkan genetic code Menghubungkan between nucleic acids with amino acid protein.
5. Small nuclear RNA snRNA : -assist the process of splicing in the post transcription process.
The basic structure of RNA similar to DNA. RNA is a polymer composed of a number of nucleotides. Each nucleotide has a phosphate group, a ribose sugar group, and one group of nitrogen bases (base N). Polymer composed of the alternating bond between a phosphate group from one nucleotide with a ribose sugar group of another nucleotide.
The difference lies in the RNA with the DNA of one additional hydroxyl group on the ribose sugar ring (so called ribose). Nitrogen bases in RNA similar to DNA, except for thymine bases in DNA is replaced by uracil in RNA. So still there are four choices: adenine, guanine, cytosine, or uracil to the nucleotide. In addition, the conformation of double helical RNA does not form as DNA, but varied according to the type and function.
RNA Type
RNA is present in nature in many kinds / types. As the genetic material, RNA tangible pair ribbon (UK double-stranded RNA, dsRNA). Classical molecular genetics teaches that there are three types of RNA are involved in the process of protein synthesis:
1. Messenger RNA (English: messenger-RNA, mRNA)
2. RNA-ribosome (English: ribosomal-RNA, rRNA)
3. RNA-transfer (English: the transfer-RNA, tRNA).
MRNA structure said to be the primary structure, whereas tRNA and rRNA structures said to be a secondary structure. Differences among the three structures of RNA molecules is related to differences in their respective functions
At the end of the 20th century and early 21st century is known that RNA is present in various forms and are involved in the process pascatranslasi. In regulating the genetic expression of people are now familiar with the micro-RNA (Mirna) involved in the "reduction of genes" or gene silencing and small-interfering RNA (siRNA) that are involved in defense against viral attack
Cutting-edge research on RNA function showed evidence supporting the theory of 'RNA world', which states that at the beginning of the process of evolution, RNA is the genetic material of living organisms using universal before DNA.
Unlike DNA, RNA molecules are generally single-stranded form so it does not have a spiral staircase structure. However, structural modifications also occur due to the formation of hydrogen bonds in a single strand itself (intramolekuler).
With the modification of the structure of RNA molecules, we recognize three kinds of RNA, the messenger RNA or messenger RNA (mRNA), transfer RNA or transfer RNA (tRNA) and ribosomal RNA (rRNA). MRNA structure said to be the primary structure, whereas tRNA and rRNA structures said to be a secondary structure. Differences among the three structures of RNA molecules is related to differences in their respective functions.
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