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| the basic unit of heredity in a living organism |
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| difference between rna and dna |
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RNA is usually single-stranded, while DNA is usually double-stranded; RNA nucleotides contain ribose while DNA contains deoxyribose (a type of ribose that lacks one oxygen atom); and RNA has the base uracil rather than thymine that is present in DNA. RNA is transcribed from DNA by enzymes called RNA polymerases and is generally further processed |
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| the synthesis of RNA under the direction of DNA. RNA synthesis, or transcription, is the process of transcribing DNA nucleotide sequence information into RNA sequence information |
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| where does transcription occur? |
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| a molecule of RNA encoding a chemical "blueprint" for a protein product. mRNA is transcribed from a DNA template, and carries coding information to the sites of protein synthesis: the ribosomes |
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| is a small RNA (usually about 74-95 nucleotides) that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. |
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| the central component of the ribosome, the protein manufacturing machinery of all living cells. The function of the rRNA is to provide a mechanism for decoding mRNA into amino acids and to interact with the tRNAs during translation by providing peptidyl transferase activity. |
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| Proteins are assembled from amino acids using information encoded in genes. Each protein has its own unique amino acid sequence that is specified by the nucleotide sequence of the gene encoding this protein. |
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| first stage of protein biosynthesis (part of the overall process of gene expression). Translation is the production of proteins by decoding mRNA produced in transcription. Translation occurs in the cytoplasm where the ribosomes are located |
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| set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells. Specifically, the code defines a mapping between tri-nucleotide sequences called codons, and amino acids; every triplet of nucleotides in a nucleic acid sequence specifies a single amino acid |
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| initiation codon (start codon). Unlike stop codons, the codon alone is not sufficient to begin the process. Nearby sequences and initiation factors are also required to start translation. The most common start codon is AUG, which also codes for methionine. There are sometimes other alternative start codons (depending on the organism), such as "UUG" which normally codes for leucine. However, when used as a start codon these alternative start codons are usually translated as methionine (regardless of their normal meaning).[2] |
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| UAG is amber, UGA is opal (sometimes also called umber), and UAA is ochre. "Amber" was named by discoverers Richard Epstein and Charles Steinberg after their friend Harris Bernstein, whose last name means "amber" in German. The other two stop codons were named 'ochre" and "opal" in order to keep the "color names" theme. Stop codons are also called termination codons and they signal release of the nascent polypeptide from the ribosome due to binding of release factors in the absence of cognate tRNAs with anticodons complementary to these stop signals.[3] |
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| enable cells to make proteins needed for basic functions; dubbed housekeeping genes, they are active in many types of cells. Other genes, however, are inactive most of the time. Some genes play a role in early development of the embryo and are then shut down forever. Many genes encode proteins that are unique to a particular kind of cell and that give the cell its character - making a brain cell, say, different from a bone cell. A normal cell activates just the genes it needs at the moment and actively suppresses the rest. |
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