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43 Cards in this Set
- Front
- Back
gene
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a DNA sequence whose final product is either a polypeptide or an RNA molecule.
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gene expression
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DNA-directed synthesis of proteins (or RNAs)
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RNA
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the link between a gene and teh protein for which it codes
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transcription
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transfer of information from DNA to messenger RNA or another type of RNA using the "laguage" of nucleic acids.
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Translation
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transfers information from mRNA to a polypeptide, changing from the language of nucleotides to that of amino acids.
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ribosomes
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sites of translation( synthesis of a polypeptide).
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messenger RNA
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a type of RNA, synthesized using a DNA template, that attaches to ribosomes n the cytoplasm and specifies hte primary structure of a protein.
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RNA processing
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the modification of pre-mRNA or of the primary transcript of any gene within the nucleus, occurs only in eukaryotes.
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triplet code
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the translation of nucleotides into amino acids uses this to specify each amino acid.
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template strand
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base triplets along this strand are transcribed into mRNA codons.
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codon
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a three-nucleotide sequence of DNA or mRNA that specifies a praticular amino acid or termination signal; the basic unit of the genetic code
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redundant code
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more than one codon can specify a single amino acid, but no codon specifies two different amino acids.
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reading frame
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starting at a start codon and reading each triplet sequentially
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promoter
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the DNA sequence where RNA polymerase attaches and initiates transcription. The binding site for RNA polymerase and determines where transcription starts and which DNA strnad is used as the template.
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RNA polymerase
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an enzyme that links ribonucleotides into a grwoing RNA chain during transcription.
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terminator
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in bacteria, the sequence that signals the end of transcription.
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transcription unit
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the sequence of DNA that is transcribed into one RNA molecule
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RNA polymerase II
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synthesizes mRNA
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TATA box
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a recognition sequence common in eukaryotes, upstream from the start point, crucial for forming the transcirption initiation complex.
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transcription factors
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in eukaryotes, must first recognize and bind to the promoter before RNA polymerase II can attach.
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transcription initiation complex
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the completed assembly of transcription factors and RNA polymerase bound to a promoter.
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RNA polymerase
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untwists the double helix, exposing DNA nucleotides for base pairing with RNA nucleotides, adn joins the nucleoptides to the 3' end of the growing polymer.
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poly-A tail
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a sequence of 50 to 250 adenine nucleotides added onto the 3' end of a pre-mRNA molecule.
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5' cap
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a modified form of guanine nucleotide added onto the nucleotide at the 5' end of a pre-mRNA molecule.
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introns
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long sections of non-coding bases, intervening sequences, occur wihtin the boundaries of eukaryotic genes.
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exons
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coding regions expressed in protein synthesis
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RNA splicing
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the removal of portions(introns) of the transcriptthat will not be included in the mRNA.
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spliceosome
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a large complex made up of proteins and RNA molecules that splices RNA by interacting wiht the ends of an RNA intron, releasing the intron adn joining two adjacent exons.
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ribozymes
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RNA molecules that act like enzymes
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alternative RNA splicing
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allows some genes to produce different polypeptides.
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domains
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functional segments of a protein, such as binding and active sites.
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transfer RNA (tRNA)
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molecules that carry specific amino acids to ribosomes, each have an anitcodon, that base-pairs with complementary mRNA, assuring that amino acids arranged in the sequence prescribed by the transcription of DNA.
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anticodon
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base triplet, a nucelotide triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule.
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aminoacyl-tRNA synthetase
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each amino acid has one, attaches to its appropriate tRNA molecules to create an aminoacyl tRNA, driven by hydolysis of ATP.
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wobble
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enables the third nucleotide of some tRNA anticodons to pair with more than one kind of base in the codon.
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ribosomal RNA
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the most abundant type fo RNA, which together with proteins makes up ribosomes.
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P site
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ribosomes binding site for RNA, that holds the tRNA carrying the growing polypeptide chain
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A site
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holds the tRNA carrying the next amino acid
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E site
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exit site from whihc discharged tRNAs leave the ribosome.
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iniation factors
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helps subunit of ribosome attach to small one and from translation intitiation complex.
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elongation factors
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proteins invovled in the elongation stage of protein synthesis.
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polyribosomes(polysomes)
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an mRNA can be translated simultaneously by several ribosomes in strings
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signal peptide
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if a protein is destined for the endomembrane system or for secretion.
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