Biological Function Of Dna And Rna Pdf
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Nucleic acid , naturally occurring chemical compound that is capable of being broken down to yield phosphoric acid , sugars, and a mixture of organic bases purines and pyrimidines. Nucleic acids are the main information-carrying molecules of the cell , and, by directing the process of protein synthesis , they determine the inherited characteristics of every living thing. DNA is the master blueprint for life and constitutes the genetic material in all free-living organisms and most viruses.
- Role of RNA in Biology
- DNA structure and function
- The Differences Between DNA and RNA
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Genes are composed of DNA and are linearly arranged on chromosomes.
RNA, in one form or another, touches nearly everything in a cell. RNA carries out a broad range of functions, from translating genetic information into the molecular machines and structures of the cell to regulating the activity of genes during development, cellular differentiation, and changing environments. RNA is a unique polymer.
Role of RNA in Biology
RNA, in one form or another, touches nearly everything in a cell. RNA carries out a broad range of functions, from translating genetic information into the molecular machines and structures of the cell to regulating the activity of genes during development, cellular differentiation, and changing environments. RNA is a unique polymer. It can also bind specific proteins or small molecules, and, remarkably, RNA can catalyze chemical reactions, including joining amino acids to make proteins.
Genes that are copied—"transcribed"—into the instructions for making individual proteins are often referred to as "coding genes.
Several key classes of RNA molecules help convert the information contained in the cell's DNA into functional gene products like proteins. Messenger RNAs mRNAs are copies of individual protein-coding genes, and serve as an amplified read-out of each gene's nucleic acid sequence.
Ribosomal RNA rRNA constitutes the core structural and enzymatic framework of the ribosome, the machine that synthesizes proteins according to the instructions contained in the sequence of an mRNA. Transfer RNAs tRNAs use complementary base pairing to decode the three-letter "words" in the mRNA, each corresponding to an amino acid to be sequentially incorporated into a growing protein chain. Most RNA molecules, once transcribed from the chromosomal DNA, require structural or chemical modifications before they can function.
Spliceosomal RNAs help discard intervening sequences introns from pre-mRNA transcripts and splice together the mRNA segments exons to create what can be a complex assortment of distinct protein-coding mRNAs from a single gene. Many noncoding RNAs also require post-transcriptional modifications. For instance, ribosomal RNAs receive numerous chemical modifications that are required for proper ribosome assembly and function. Regulation of the production of proteins from coding genes is the basis for much of cellular and organismal structure, differentiation, and physiology.
Diverse classes of noncoding RNAs participate in gene regulation at many levels, affecting the production, stability, or translation of specific mRNA gene products. In prokaryotes for example, bacteria , small antisense RNAs exert a variety of gene regulatory activities by base pairing specifically to their target mRNAs.
Also common in prokaryotes are riboswitches, noncoding RNA sequences that usually function as regulatory domains contained within longer mRNAs. Riboswitches regulate the activity of their host mRNAs by binding to small molecules such as nucleotides or amino acids, sensing the abundance of those small molecules and regulating the genes that make or use them accordingly.
For example, microRNAs miRNAs are regulatory RNAs approximately 22 nt long that are produced from longer transcripts that contain a certain kind of double-stranded "hairpin" structure.
There are hundreds of miRNA genes in plants and animals, and each miRNA can regulate the activity of hundreds of protein-coding genes. Therefore, miRNAs individually and collectively have a profound impact on the development and physiology of multicellular eukaryotes. Unlike miRNAs, which are produced from specific genetic loci that have evolved to regulate mRNAs, siRNAs can derive from essentially any transcribed region of the genome.
A major role for certain classes of small noncoding RNAs is defense of the cell against viruses, transposons, and other nucleic acid sequences that pose a potential threat to cellular homeostasis or genome stability. The response of some cells against viral infection includes the production of siRNAs complementary to the virus.
Many endogenous siRNAs in eukaryotic cells specify the silencing of transposons and repeat sequences that are already resident in the genome. Another class of regulatory RNA consists of diverse kinds of longer noncoding transcripts that generally function to regulate the expression of distant genetic loci, often by suppressing or promoting their transcription.
For example, the rox RNAs of the fruit fly seems to facilitate the remodeling of chromosome structure to allow the male X chromosome to be transcribed at twice the rate as a single X chromosome in females, which have two X's. Similarly, the Xist RNA in mammals helps inactivate one of the two X chromosomes in females, allowing males and females to have equivalent levels of gene expression from the X chromosome.
RNA molecules regulate gene expression Regulation of the production of proteins from coding genes is the basis for much of cellular and organismal structure, differentiation, and physiology.
DNA structure and function
Metrics details. Of all the molecules in nature, DNA is the most exalted. The blueprint of life, DNA bears the genetic code inscribed in the famous double helix. The structure of DNA is elegant, magisterial, even sublime. First, DNA is an informational macromolecule. In the past decades, this conceptualization has undergone a paradigm shift that has left many investigators positively shaking. While CpG motifs an unmethylated cytosine guanosine dinucleotide are particularly active, a requirement for a CpG motif can be overcome by the binding of DNA to proteins that effectively transfect DNA into cells to interact with both toll-like TLR and non-toll-like internal nucleic acid receptors.
DNA deoxyribonucleic acid is the genomic material in cells that contains the genetic information used in the development and functioning of all known living organisms. DNA, along with RNA and proteins, is one of the three major macromolecules that are essential for life. Within the nucleus of eukaryotic cells, DNA is organized into structures called chromosomes. The complete set of chromosomes in a cell makes up its genome; the human genome has approximately 3 billion base pairs of DNA arranged into 46 chromosomes. DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds.
The Differences Between DNA and RNA
Deoxyribonucleic acid, or DNA, is a molecule that contains the instructions an organism needs to develop, live and reproduce. These instructions are found inside every cell, and are passed down from parents to their children. DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine A , thymine T , guanine G and cytosine C.
DNA is the genetic material found in all living organisms, ranging from single-celled bacteria to multicellular mammals. It is found in the nucleus of eukaryotes and in the chloroplasts and mitochondria. In prokaryotes, the DNA is not enclosed in a membranous envelope, but rather free-floating within the cytoplasm. The entire genetic content of a cell is known as its genome and the study of genomes is genomics. In eukaryotic cells, but not in prokaryotes, DNA forms a complex with histone proteins to form chromatin, the substance of eukaryotic chromosomes.
Nucleic acids are the biopolymers , or large biomolecules , essential to all known forms of life. They are composed of nucleotides , which are the monomers made of three components: a 5-carbon sugar , a phosphate group and a nitrogenous base.
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This is a comparison of the differences between DNA versus RNA, including a quick summary and a detailed table of the differences. This table summarizes the key points:. Also, RNA is found in prokaryotes , which are believed to precede eukaryotes. RNA on its own can act as a catalyst for certain chemical reactions.
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But why is DNA, and not RNA, now the dominant biological information store? We argue that, in addition to its coding function, the ability of.