Term
| One gene, one enzyme hypothesis |
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Definition
| is the idea that genes act through the production of enzymes, with each gene responsible for producing a single enzyme that in turn affects a single step in a metabolic pathway. |
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Term
| One gene, one polypeptide relationship |
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Definition
| Each gene codes for the production of a specific polypeptide |
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Term
| Central dogma of molecular biology |
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Definition
| s an explanation of the flow of genetic information within a biological system. The central dogma has also been described as "DNA makes RNA and RNA makes protein," a positive statement which was originally termed the sequence hypothesis by Crick. |
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Term
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Definition
| s a large family of RNA molecules that convey genetic information from DNA to the ribosome, where they specify the amino acid sequence of the protein products of gene expression. Following transcription of primary transcript mRNA (known as pre-mRNA) by RNA polymerase, processed, mature mRNA is translated into a polymer of amino acids: a protein, as summarized in the central dogma of molecular biology. |
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Term
| Precursor mRNA (pre-mRNA) |
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Definition
| is an immature single strand of messenger ribonucleic acid (mRNA). Pre-mRNA is synthesized from a DNA template in the cell nucleus by transcription. Pre-mRNA comprises the bulk of heterogeneous nuclear RNA (hnRNA). |
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Term
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Definition
| the normal version of the genetic code in which a sequence of three nucleotides codes for the synthesis of a specific amino acid |
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Term
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Definition
| a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule. |
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Term
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Definition
| is used as a template for RNA synthesis. As transcription proceeds, RNA polymerase traverses the template strand and uses base pairing complementarity with the DNA template to create an RNA copy. |
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Term
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Definition
| s the DNA strand which has the same base sequence as the RNA transcript produced (although with thymine replaced by uracil). It is this strand which contains codons, while the non-coding strand contains anti-codons. |
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Term
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Definition
| is the set of rules by which information encoded within genetic material (DNA or mRNA sequences) is translated into proteins by living cells. Biological decoding is accomplished by the ribosome, which links amino acids in an order specified by mRNA, using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. |
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Term
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Definition
| is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. The start codon always codes for methionine in eukaryotes and a modified Met (fMet) in prokaryotes. The most common start codon is AUG. |
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Term
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Definition
| s a nucleotide triplet within messenger RNA that signals a termination of translation. Proteins are based on polypeptides, which are unique sequences of amino acids. Most codons in messenger RNA (from DNA) correspond to the addition of an amino acid to a growing polypeptide chain, which may ultimately become a protein. |
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Term
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Definition
| is an enzyme that produces primary transcript RNA. In cells, RNAP is necessary for constructing RNA chains using DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses. In chemical terms, RNAP is a nucleotidyl transferase that polymerizes ribonucleotides at the 3' end of an RNA transcript. |
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Term
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Definition
| s a region of DNA that initiates transcription of a particular gene. Promoters are located near the transcription start sites of genes, on the same strand and upstream on the DNA (towards the 5' region of the sense strand). Promoters can be about 100–1000 base pairs long. |
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Term
| Transcription termination site |
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Definition
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Term
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Definition
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Term
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Definition
| Upstream is toward the 5' end of the RNA molecule and downstream is toward the 3' end. When considering double-stranded DNA, upstream is toward the 5' end of the coding strand for the gene in question and downstream is toward the 3' end. Due to the anti-parallel nature of DNA, this means the 3' end of the template strand is upstream of the gene and the 5' end is downstream. |
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Term
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Definition
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Term
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Definition
| s the RNA component of the ribosome, and is essential for protein synthesis in all living organisms. It constitutes the predominant material within the ribosome, which is approximately 60% rRNA and 40% protein by weight. |
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Term
| Small nuclear RNA (snRNA) |
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Definition
| a class of small RNA molecules that are found within the splicing speckles and Cajal bodies of the cell nucleus in eukaryotic cells. |
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Term
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Definition
| s a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. tRNAs function at specific sites in the ribosome during translation, which is a process that synthesizes a protein from an mRNA molecule. |
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Term
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Definition
| The polymerizing unit (in this case, RNA polymerase) is directed to the site; that is, there is something on the site that both flags the polymerase to stop there, and orients it in the proper direction. |
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Term
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Definition
| This is where the polymerizing unit does it’s “job”; in this case, laying down nucleotides complementary to the template strand, and fusing the sugar-phosphate backbone to form a new RNA strand. |
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Term
| transcription termination |
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Definition
| this is where the polymerase stops (hence, the name). Like in initiation, there needs to be some sort of flag to signal the stopping point. |
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Term
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Definition
| is a specially altered nucleotide on the 5′ end of some primary transcripts such as precursor messenger RNA. This process, known as mRNA capping, is highly regulated and vital in the creation of stable and mature messenger RNA able to undergo translation during protein synthesis. |
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Term
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Definition
| consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. |
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Term
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Definition
| s the addition of a poly(A) tail to a messenger RNA. The poly(A) tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In eukaryotes, polyadenylation is part of the process that produces mature messenger RNA (mRNA) for translation. It, therefore, forms part of the larger process of gene expression. |
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Term
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Definition
| s any nucleotide sequence within a gene that is removed by RNA splicing during maturation of the final RNA product. The term intron refers to both the DNA sequence within a gene and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final mature RNA after RNA splicing are exons. |
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Term
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Definition
| s any part of a gene that will encode a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. |
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Term
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Definition
| are components of an organism's DNA that do not encode protein sequences. |
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Term
| nucleic acid hybridization |
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Definition
| A technique in which single-stranded nucleic acids (DNA or RNA) are allowed to interact so that complexes called hybrids are formed by molecules with similar, complementary sequences. |
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Term
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Definition
| s the editing of the nascent pre-messenger RNA (pre-mRNA) transcript in which introns are removed and exons are joined together (ligated). For nuclear-encoded genes, splicing takes place within the nucleus either co-transcriptionally or immediately after transcription. |
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Term
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Definition
| are RNA-protein complexes that combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs. The action of snRNPs is essential to the removal of introns from pre-mRNA, a critical aspect of post-transcriptional modification of RNA, occurring only in the nucleus of eukaryotic cells. |
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Term
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Definition
| is a large and complex molecular machine found primarily within the splicing speckles of the cell nucleus of eukaryotic cells. The spliceosome is assembled from snRNAs and protein complexes. The spliceosome removes introns from a transcribed pre-mRNA, a kind of primary transcript. This process is generally referred to as splicing. |
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Term
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Definition
| means it has an amino acid attached. And a charged tRNA can read the codon of mRNA during translation. the charged tRNA mean that the correct amino acid is attached. uncharged means no amino acid is attached. |
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Term
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Definition
| a sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA. |
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Term
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Definition
| a sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA. |
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Term
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Definition
| is a pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules. The four main wobble base pairs are guanine-uracil (G-U), hypoxanthine-uracil (I-U), hypoxanthine-adenine (I-A), and hypoxanthine-cytosine (I-C). |
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Term
| Aminoacyl-tRNA synthetase |
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Definition
| is an enzyme that attaches the appropriate amino acid onto its tRNA. It does so by catalyzing the esterification of a specific cognate amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA. |
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Term
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Definition
| is a complex molecular machine found within all living cells, that serves as the site of biological protein synthesis (translation). Ribosomes link amino acids together in the order specified by messenger RNA (mRNA) molecules |
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Term
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Definition
| contains the active site of the ribosome: the site that creates the new peptide bonds when proteins are synthesized. In this view, the messenger RNA would run horizontally in the groove across the middle. |
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Term
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Definition
| is in charge of information flow during protein synthesis. It initially finds a messenger RNA strand and, after combining with a large subunit, ensures that each codon in the message is paired with the anticodon in the proper transfer RNA. |
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Term
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Definition
| Site on the ribosome through which tRNAs pass after they have donated their amino acid to the growing nascent polypeptide chain. |
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Term
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Definition
| the ribosomal site most frequently occupied by aminoacyl-tRNA. The aminoacyl-tRNA in the A-site functions as the acceptor for the growing protein during peptide bond formation. |
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Term
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Definition
| the ribosomal site most frequently occupied by peptidyl-tRNA, i.e. the tRNA carrying the growing peptide chain. The P-site is also referred to as the puromycin sensitive site. Puromycin is an antibiotic which shows similarities with a part of aminoacyl-tRNA. When puromycin is present in the A-site, the peptide can be linked to puromycin via a peptide bond. Thus, peptidyl-tRNA in the P-site is located in the puromycin sensitive site. |
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Term
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Definition
| it's the addition of amino acids by the formation of peptide bonds. Elongation is just what it sounds like: a chain of amino acids grows longer and longer as more amino acids are added on. This will eventually create the polypeptide. |
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Term
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Definition
| the mRNA, the tRNA, and the first amino acid all come together within the ribosome. The mRNA strand remains continuous, but the true initiation point is the start codon, AUG. |
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Term
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Definition
| At a stop codon, a release factor reads the triplet, and polypeptide synthesis ends; the polypeptide is released from the tRNA, the tRNA is released from the ribosome, and the two ribosomal subunits separate from the mRNA. |
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Term
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Definition
| the primary enzymatic function of the ribosome, which forms peptide bonds between adjacent amino acids using tRNAs during the translation process of protein biosynthesis. |
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Term
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Definition
| a protein that allows for the termination of translation by recognizing the termination codon or stop codon in an mRNA sequence. |
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Term
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Definition
| a cluster of ribosomes held together by a strand of messenger RNA that each ribosome is translating. |
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Term
| Signal sequence (or signal peptide) |
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Definition
| is a short (5-30 amino acids long) peptide present at the N-terminus of the majority of newly synthesized proteins that are destined towards the secretory pathway.[1] These proteins include those that reside either inside certain organelles (the endoplasmic reticulum, golgi or endosomes), secreted from the cell, or inserted into most cellular membranes. |
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Term
| Nuclear localization signal |
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Definition
| s an amino acid sequence that 'tags' a protein for import into the cell nucleus by nuclear transport. Typically, this signal consists of one or more short sequences of positively charged lysines or arginines exposed on the protein surface. |
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Term
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Definition
| s the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called proteases, but may also occur by intra-molecular digestion. Low pH or high temperatures can also cause proteolysis non-enzymatically. |
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Term
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Definition
| the addition of a saccharide unit to a protein |
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Term
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Definition
| s the addition of a phosphoryl group (PO3) to a molecule. Phosphorylation and its counterpart, dephosphorylation, turn many protein enzymes on and off, thereby altering their function and activity. |
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