Term
| basal transcription factors |
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Definition
| proteins that initiate eukaryotic transcription by matching the enzyme with the appropriate promoter region in DNA; • analogous to the function of sigma proteins in bacteria, except that basal transcription factors interact with DNA independent of RNA polymerase |
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| located 30 base pairs upstream of the transcription start site; some of the promoters recognized by pol II don’t contain a TATA box |
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| regions of eukaryotic genes that are part of the final mRNA; they are expressed |
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| untranslated stretches of eukaryotic genes; they are intervening; cause eukaryotic genes to be much longer than their corresponding mature RNA transcripts |
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| generated by transcription of eukaryotic genes by RNA polymerase; contains introns and exons |
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| process by which introns are removed from growing RNA strand; occurs while transcription is still under way; results in an RNA that contains an uninterrupted genetic message; catalyzed by snRNPs/RNA molecules in the spliceosome (catalytic RNA molecules are called ribozymes) |
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Term
| small nuclear ribonucleoproteins (snRNPs) |
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Definition
| catalyze splicing; small complex of proteins and small RNAs |
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| multipart complex formed by many snRNPs and other proteins |
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Definition
| made of 7-methylguanylate and three phosphate groups; serves as recognition signal for translation machinery |
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| long tract of 100-250 adenine nucleotides; added at 3' end of RNA; not encoded on template strand; extends life span of mRNA by protecting message from degradation by ribonucleases in cytosol |
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| begins when initial snRNP binds to 5' exon-intron boundary; spliceosome forms; intron forms a loop with an adenine ribonucleotide at its base, which then cuts the loop; phosphodiester bond links exons on either side, completing splicing; introns usually degraded to ribonucleotide monophosphates |
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Definition
| enzymes add 5’ cap to 5’ end of RNA emerges from RNA polymerase; after addition of cap and tail, processing of the primary RNA transcript is complete – product is mature mRNA; 5’ and 3’ untranslated regions help stabilize mature RNA and regulate its translation |
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Term
| transcription in bacteria vs. eukaryotes |
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Definition
| similar in that RNA polymerase doesn't bind directly to promoter sequences by itself (basal transcription factors); bacteria: single sigma protein binds to promoter and initiates transcription & eukaryotes: many basal transcription factors required to initiate transcription (complex machinery to start transcription); eukaryotes: three distinct types of RNA polymerase instead of one; eukaryotes: promoters in eukaryotic DNA much more diverse and complex than bacterial promoters - many of the eukaryotic promoters recognized by pol III include TATA box (pol I and pol III interact with entirely different promoters); eukaryotes: transcription is followed by several important RNA processing steps that result in production of an mRNA that leaves the nucleus; eukaryotes: genes don’t consist of one continuous DNA sequence that codes for a product, as do bacterial genes (• regions of eukaryotic genes that code for proteins come in pieces that are separated by hundreds or thousands of intervening DNA bases) |
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Term
| three distinct types of RNA polymerase in eukaryotes |
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Definition
| RNA pol I, pol II, and pol III – each transcribe a discrete class of RNA; only RNA pol II transcribes genes that code for proteins (produces mRNA); pol I makes large RNA molecules found in ribosomes; pol III manufactures one of the small RNAs found in ribosomes and tRNAs |
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Term
| major differences between bacterial and eukaryotic transcription |
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Definition
| slicing and addition of caps and tails |
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Term
| protein-coding regions of eukaryotic genes are interrupted by ____ |
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Definition
| stretches of noncoding DNA |
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| translation occurs in the _____ |
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| primary function of RNA polymerase II is _______ |
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Definition
| transcription of protein-coding genes |
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Term
| TATA box of the eukaryotic promoter is analogous to the _____ of the prokaryotic promoter |
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| transcription in eukaryotes vs prokaryotes |
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| Sharp - tried to figure out how DNA templates are transcribed |
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Definition
| heated DNA molecules enough separate two strands; single-stranded DNA incubated with mRNA encoded by the sequence; idea was to promote base pairing between mRNA and single-stranded DNA; expected mRNA to form base pairs with the DNA that was the template for its synthesis; instead, parts of DNA formed loops; interpreted these loops as stretches of nucleotides that are present in DNA template strand but not in corresponding mRNA |
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Term
| Britten tested hypothesis that ribosomes were site of protein synthesis |
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Definition
| pulse-chase experiment to label a population of molecules as they are produced; fed radioactive sulfate (35SO4-2) to E. coli; expected cells to incorporate radioactive sulfur into amino acids that contain sulfur (methionine and cysteine) and then into newly made proteins; followed by large excess of nonradioactive sulfate; radioactive signal was associated with ribosomes for a short period of time, then found in proteins not in ribosomes; proteins are synthesized at ribosomes and then released |
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Term
| in bacteria, ribosomes attach to mRNAs and begin synthesizing proteins even before _______ |
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Definition
| transcription is complete |
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Term
| attachment of an amino acid to a tRNA requires ________ |
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Definition
| an input of energy in form of ATP |
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Term
| discovery of basal transcription factors |
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Definition
| purified RNA polymerase from human cells, added template DNA and analyze RNAs produced; RNA polymerase was found copying at random locations on template DNA instead of at promoter regions; when RNA polymerase was alone, both strands of DNA transcribed instead of one; made them think there was a sigma-like protein required for normal transcription; to test this, added proteins one or a few at a time and recorded which ones enabled RNA polymerase to bind to promoters and correctly transcribe the template strand |
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