DNA only infect human but RNA doesn't infect human:
- True.
- False. ***
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Ribonucleic acid or (RNA) is a type of nucleic acid, a linear polymeric molecule formed by smaller units called nucleotides. It intervenes in several important biological functions such as genetic coding and decoding during protein translation, regulation and gene expression. It is one of the essential macromolecules for life, along with DNA, proteins, lipids and carbohydrates. Like DNA, RNA is made up of a nucleotide strand, but unlike DNA, which forms a two-stranded double helix, most RNAs are single-stranded, although they can fold over themselves. Cellular organisms use messenger RNA (mRNA) to carry genetic information to the ribosome (using the sequence of bases G, A, U, and C meaning guanine, adenine, uracil and cytosine), where they will coordinate the synthesis of specific proteins. The uracil base is characteristic of RNA (DNA in turn has thymine). RNA nucleotides carry ribose sugar, hence its name (ribose> ribonucleic), unlike deoxyribose DNA. RNA is transcribed from DNA by the action of enzymes called play a role to catalyze biolontrol reactions to gene expression, or to perceive and communicate responses to cellular signals. One of these active processes is protein synthesis, a fundamental universal function in which various types of RNA intervene: mRNA provides information on how the protein sequence has to be, tRNA takes the necessary amino acids, and rRNA is a constituent part. of the organelle in which the ribosome is synthesized, and has a catalytic activity that joins the amino acids together. Ribozymes are RNAs with enzymatic function. Many viruses encode their genetic information in an RNA genome.
Features:
RNA consists of a ribose, a phosphate group and a nitrogenous base.
The composition of the RNA is very similar to that of DNA (deoxyribonucleic acid) but has some differences:
1. RNA is made up of a single strand of nucleotides, not a double stranded one like DNA. An RNA strand can bend such that part of its own bases resemble each other. Such intramolecular base pairing is an important determinant of RNA form. Thus, by forming intrachain bridges, RNA is capable of assuming a much larger variety of complex three-dimensional molecular forms than the DNA double helix.
2. RNA has ribose sugar in its nucleotides instead of deoxyribose found in DNA. As the names suggest, the two sugars differ in the presence or absence of only one oxygen atom. The RNA sugar groups contain a 2 'carbon-linked oxygen-hydrogen pair, while only one hydrogen atom is bonded to the 2' carbon in the DNA sugar groups. Complex sugars also appear to bind to some RNA molecules.
As an individual DNA strand, an RNA strand is formed from a sugar phosphate backbone with a base covalently linked at the 1 'position of each ribose. Sugar-phosphate bonds are made at the 5 'and 3' positions of sugar, as in DNA. Thus, an RNA strand will have a 5 'end and a 3' end.
4- RNA nucleotides (called ribonucleotides) contain adenine (A), guanine (G), cytosine (C) and uracil (U) bases, but the latter pyrimidine is present in place of thymine.
5. RNA, like protein but not DNA, can catalyze important biological reactions. RNA molecules that function as enzymatic proteins are called ribozymes.
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Ribonucleic acid or (RNA) is a type of nucleic acid, a linear polymeric molecule formed by smaller units called nucleotides. It intervenes in several important biological functions such as genetic coding and decoding during protein translation, regulation and gene expression. It is one of the essential macromolecules for life, along with DNA, proteins, lipids and carbohydrates. Like DNA, RNA is made up of a nucleotide strand, but unlike DNA, which forms a two-stranded double helix, most RNAs are single-stranded, although they can fold over themselves. Cellular organisms use messenger RNA (mRNA) to carry genetic information to the ribosome (using the sequence of bases G, A, U, and C meaning guanine, adenine, uracil and cytosine), where they will coordinate the synthesis of specific proteins. The uracil base is characteristic of RNA (DNA in turn has thymine). RNA nucleotides carry ribose sugar, hence its name (ribose> ribonucleic), unlike deoxyribose DNA. RNA is transcribed from DNA by the action of enzymes called play a role to catalyze biolontrol reactions to gene expression, or to perceive and communicate responses to cellular signals. One of these active processes is protein synthesis, a fundamental universal function in which various types of RNA intervene: mRNA provides information on how the protein sequence has to be, tRNA takes the necessary amino acids, and rRNA is a constituent part. of the organelle in which the ribosome is synthesized, and has a catalytic activity that joins the amino acids together. Ribozymes are RNAs with enzymatic function. Many viruses encode their genetic information in an RNA genome.
Features:
RNA consists of a ribose, a phosphate group and a nitrogenous base.
The composition of the RNA is very similar to that of DNA (deoxyribonucleic acid) but has some differences:
1. RNA is made up of a single strand of nucleotides, not a double stranded one like DNA. An RNA strand can bend such that part of its own bases resemble each other. Such intramolecular base pairing is an important determinant of RNA form. Thus, by forming intrachain bridges, RNA is capable of assuming a much larger variety of complex three-dimensional molecular forms than the DNA double helix.
2. RNA has ribose sugar in its nucleotides instead of deoxyribose found in DNA. As the names suggest, the two sugars differ in the presence or absence of only one oxygen atom. The RNA sugar groups contain a 2 'carbon-linked oxygen-hydrogen pair, while only one hydrogen atom is bonded to the 2' carbon in the DNA sugar groups. Complex sugars also appear to bind to some RNA molecules.
As an individual DNA strand, an RNA strand is formed from a sugar phosphate backbone with a base covalently linked at the 1 'position of each ribose. Sugar-phosphate bonds are made at the 5 'and 3' positions of sugar, as in DNA. Thus, an RNA strand will have a 5 'end and a 3' end.
4- RNA nucleotides (called ribonucleotides) contain adenine (A), guanine (G), cytosine (C) and uracil (U) bases, but the latter pyrimidine is present in place of thymine.
5. RNA, like protein but not DNA, can catalyze important biological reactions. RNA molecules that function as enzymatic proteins are called ribozymes.
Information Transfer Intermediate:
In 1957 Elliot Volkin and Lawrence Astrachan made a significant remark. They found that one of the most striking changes when E. coli is infected by T2 phage is a rapid burst of RNA synthesis. In addition, this phage-induced RNA "renews" rapidly; that is, its life span is short. Its rapid onset and disappearance suggested that RNA may play some role in the T2 genome expression needed to make more virus particles.
Volkin and Astrachan demonstrated rapid RNA renewal using a protocol called the pulse-hunting experiment. To perform a pulse-hunting experiment, the infected bacteria are first fed (pulsed with) radioactive uracil (a molecule needed for RNA synthesis but not DNA). Any RNA synthesized in the bacteria thereafter is "labeled" with readily detectable radioactive uracil. After a short incubation period, radioactive uracil is removed and replaced (hunted) with non-radioactive uracil. This procedure "hunts" for RNA label removal because, as RNA degrades, only unlabeled precursors are available to synthesize new RNA molecules. RNA recovered shortly after the pulse is marked, but RNA recovered shortly after the pulse is, indicating that RNA has a very short lifespan.
A similar experiment can be done with eukaryotic cells. The cells are first pulsed with radioactive uracil to an unlabelled uracil medium. In samples taken after the pulse, most of the marking is in the nucleus. In samples obtained after hunting, labeled RNA is found in the cytoplasm. Apparently, in eukaryotes, RNA is synthesized in the nucleus and then moves to the cytoplasm, where proteins are made. Thus, RNA is a good candidate for intermediate information transfer between DNA and protein.
Summary:
RNA synthesis is usually catalyzed by the enzyme RNA polymerase, which uses DNA as a model, in a process known as transcription.
The onset of transcription begins with the binding of an enzyme to a promoter sequence in DNA (known as an upstream gene). The DNA double helix is unrolled by the activity of the helicase enzyme. The enzyme progresses along the DNA from 3 'to 5', synthesizing complementary RNA in the molecule with elongation occurring from 5 'to 3' direction. The DNA sequence also dictates when termination of RNA synthesis occurs.
RNA is often modified by enzymes after transcription. For example, the Poly-A tail and 5'-cap are added to pre-mRNA and eukaryote introns and removed by spliceosome.
There are a number of PNA polymerase-dependent RNAs that use RNA as a synthesis model for a new RNA strand. Examples are viral RNAs (such as polioviruses) that use this type of enzyme to replicate their genetic material. Some RNA polymerase-dependent RNAs are part of an interference RNA pathway in many organisms.
Transcription:
It consists of RNA synthesis. The DNA molecule opens at a certain point and free nucleotides in the cell pair with this open segment. After pairing with this open segment, the RNA molecule is ready, the DNA that served as the template reconstructs the original molecule.
Location:
In eukaryotic cells, RNA is located in the cytoplasm (most) and in the nucleus, where it is synthesized. The amount of RNA varies from cell to cell and to cell activity.
Function:
Varies with RNA class. For example, messenger RNA guides which amino acids and in what order they will be used to synthesize proteins. Generally, RNAs of the various classes discovered to date act in the processing and degradation of messenger RNAs and protein synthesis.
Structure:
Each RNA nucleotide contains a ribose, with carbons numbered from 1 'to 5'. The bases are bound to carbon 1 '. Adenine and Guanine are purines and Uracila and Cytosine are pyrimidines. The phosphate group is bonded to carbon 3 'and carbon 5' when carbon is joined.
Phosphate groups cause the charge of the molecule to be negative.
Another important structural feature that distinguishes DNA from RNA is the presence of hydroxyl on the 2 'carbon of ribose. The presence of this functional group causes the folding of the molecule to rotate towards the A-form, that is, there is an increase in the number of bases per rotation, which increases the larger groove and narrows the smaller groove, while the DNA obeys. B-DNA conformation, that described by Watson and Crick. The consequence of hydroxyl on carbon 2 'is a flexible conformation that can chemically attack the adjacent phosphodiester.
The functional form of the simple RNA strand, as well as protepines, often need a specific tertiary structure. What provides this conformational change is the secondary structure and hydrogen bonds. This leads to several domains of secondary structure, such as hairpin loops. Because RNA structures are charged, metal ions such as Mg2 + are needed to stabilize secondary and tertiary RNA structures.
Classes:
Messenger RNA:
Genes, DNA segments that serve as a template for mRNA molecules, are located on the cell's various chromosomes, usually separated by long segments of noncoding DNA. Messenger RNA (mRNA) molecules synthesized from genes have the information for protein synthesis, encoded in the form of broken nitrogen bases. Each crack is called a codon and defines each constituent amino acid of the protein.
Correspondence between the codon and its respective amino acid is made by tRNA through the anticode. For example, the UAC anti-codon tRNA fits into the mRNA only if there is the AUG codon. Since this tRNA carries the amino acid methionine, it will fit into the polypeptide chain sites corresponding to the mRNA AUG codons. Thus, tRNAs act on protein synthesis as "adapters", fitting amino acids according to mRNA codons. The ribosome, in turn, supports the coupling of mRNA and tRNAs.
RNA carrier:
Carrier RNA (tRNA) molecules are also synthesized from DNA segments present in certain specific regions of chromosomes. This type of RNA is called a carrier because it is responsible for transporting amino acid molecules to ribosomes, where they come together to form proteins. A tRNA is a relatively small molecule. At one end a specific amino acid is attached; in its middle region there is a crack of bases, the anticodon. By means of the anticodon, tRNA is temporarily paired with a complementary base crack of messenger RNA (mRNA), the codon.
Ribosomal RNA:
They are the major components of ribosomes, which are large macromolecular machinery that guide the assembly of the amino acid chain by mRNA and tRNA.
Another class of functional RNAs participate in RNA processing and is specific for eukaryotes.
This is an RNA composition with special proteins.
Small nuclear RNAs:
They are parts of a system that processes RNA transcribed in eukaryotic cells. Some snRNAs guide the modification of rRNA. Others join various protein subunits to form the ribonocleoprotein processing complex (called spliceosomes) that removes introns from eukaryotic mRNAs.
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