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38 Cards in this Set
- Front
- Back
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7-methylguanosine cap
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modification added to the 5' end of pre-mRNAs to protect mRNA from degradation and assist translation |
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aminoacyl
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tRNA synthetase enzyme that “charges” tRNA molecules by catalyzing a bond between the tRNA and a corresponding amino acid |
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anticodon
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three-nucleotide sequence in a tRNA molecule that corresponds to an mRNA codon CAAT box (GGCCAATCT) essential eukaryotic promoter sequence involved in binding transcription factors |
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Central Dogma
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states that genes specify the sequence of mRNAs, which in turn specify the sequence of proteins |
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codon
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three consecutive nucleotides in mRNA that specify the insertion of an amino acid or the release of a polypeptide chain during translation |
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colinear
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in terms of RNA and protein, three “units” of RNA (nucleotides) specify one “unit” of protein (amino acid) in a consecutive fashion |
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consensus
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DNA sequence that is used by many species to perform the same or similar functions core enzyme prokaryotic RNA polymerase consisting of α, α, β, and β' but missing σ; this complex performs elongation |
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degeneracy (of the genetic code)
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describes that a given amino acid can be encoded by more than one nucleotide triplet; the code is degenerate, but not ambiguous |
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downstream
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nucleotides following the initiation site in the direction of mRNA transcription; in general, sequences that are toward the 3' end relative to a site on the mRNA |
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exon
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sequence present in protein-coding mRNA after completion of pre-mRNA splicing |
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FACT
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complex that “facilitates chromatin transcription” by disassembling nucleosomes ahead of a transcribing RNA polymerase II and reassembling them after the polymerase passes by |
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GC-rich box
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nonessential eukaryotic promoter sequence (GGCG) that binds cellular factors to increase the efficiency of transcription; may be present several times in a promoter |
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hairpin
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structure of RNA when it folds back on itself and forms intramolecular hydrogen bonds between complementary nucleotides |
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holoenzyme
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prokaryotic RNA polymerase consisting of α, α, β, β', and σ; this complex is responsible for transcription initiation |
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initiation site
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nucleotide from which mRNA synthesis proceeds in the 5' to 3' direction; denoted with a “+1” |
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initiator tRNA
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in prokaryotes, called tRNAMf et ; in eukaryotes, called tRNAi; a tRNA that interacts with a start codon, binds directly to the ribosome P site, and links to a special methionine to begin a polypeptide chain
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intron
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non–protein-coding intervening sequences that are spliced from mRNA during processing |
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Kozak’s rules
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determine the correct initiation AUG in a eukaryotic mRNA; the following consensus sequence must appear around the AUG: 5’-GCC(purine)CCAUGG-3’; the bolded bases are most important |
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nonsense codon
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one of the three mRNA codons that specifies termination of translation |
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nontemplate strand
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strand of DNA that is not used to transcribe mRNA; this strand is identical to the mRNA except that T nucleotides in the DNA are replaced by U nucleotides in the mRNA |
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Octamer box
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nonessential eukaryotic promoter sequence (ATTTGCAT) that binds cellular factors to increase the efficiency of transcription; may be present several times in a promoter |
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peptidyl transferase
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RNA-based enzyme that is integrated into the 50S ribosomal subunit and catalyzes the formation of peptide bonds |
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plasmid
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extrachromosomal, covalently closed, circular DNA molecule that may only contain one or a few genes; common in prokaryotes |
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poly-A tail
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modification added to the 3' end of pre-mRNAs to protect mRNA from degradation and assist mRNA export from the nucleus |
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polysome
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mRNA molecule simultaneously being translated by many ribosomes all going in the same direction |
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preinitiation complex
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cluster of transcription factors and other proteins that recruit RNA polymerase II for transcription of a DNA template |
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promoter
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DNA sequence to which RNA polymerase and associated factors bind and initiate transcription |
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reading frame
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sequence of triplet codons in mRNA that specify a particular protein; a ribosome shift of one or two nucleotides in either direction completely abolishes synthesis of that protein |
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Rho-dependent termination
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in prokaryotes, termination of transcription by an interaction between RNA polymerase and the rho protein at a run of G nucleotides on the DNA template |
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Rho-independent termination
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sequence-dependent termination of prokaryotic mRNA synthesis; caused by hairpin formation in the mRNA that stalls the polymerase |
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RNA editing
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direct alteration of one or more nucleotides in an mRNA that has already been synthesized |
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Shine-Dalgarno sequence
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sequence (AGGAGG) that initiates prokaryotic translation by interacting with rRNA molecules comprising the 30S ribosome |
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signal sequence
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short tail of amino acids that directs a protein to a specific cellular compartment small nuclear RNA molecules synthesized by RNA polymerase III that have a variety of functions, including splicing pre-mRNAs and regulating transcription factors |
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splicing
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process of removing introns and reconnecting exons in a pre-mRNA start codon AUG (or rarely, GUG) on an mRNA from which translation begins; always specifies methionine |
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TATA box
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conserved promoter sequence in eukaryotes and prokaryotes that helps to establish the initiation site for transcription |
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template strand
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strand of DNA that specifies the complementary mRNA molecule |
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transcription bubble
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region of locally unwound DNA that allows for transcription of mRNA |
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upstream
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nucleotides preceding the initiationsite; in general, sequences toward the 5' end relative to a site on the mRNA |
