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Chapter 26
RNA Metabolism
26
Biochemistry
Undergraduate 3
04/08/2016

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Term
DNA-dependent RNA polymerase
Definition
requires (in addition to a DNA template) all four ribonucleoside 5'-triphosphates as precursors of the nucleotide units as well as Mg2+
Term
template strand
Definition
the strand that serves as template for RNA synthesis
Term
nontemplate strand (coding strand)
Definition
the DNA strand complementary to the template; is identical in base sequence to the RNA transcribed from the gene (with U in the RNA in place of the T in the DNA)
Term
promoters
Definition
specific sequences in the DNA to which an RNA polymerase binds; direct the transcription of adjacent segments of DNA
Term
consensus sequence
Definition
formed from certain nucleotides that are particularly common at each position despite the sequence not being identical for all bacterial promoters in a certain class
Term
cAMP receptor protein (CRP)
Definition
a protein that activates transcription in E. coli; increases the transcription of genes coding for enzymes that metabolize sugars other than glucose when cells are grown in the absence of glucose
Term
repressors
Definition
proteins that block the synthesis of RNA at specific genes
Term
transcription factors
Definition
an array of proteins required by RNA polymerase II; needed to form the active transcription complex
Term
general transcription factors
Definition
required at every Pol II promoter & are highly conserved in all eukaryotes
Term
actinomycin D
Definition
the antibiotic that inhibits the elongation of RNA strands by RNA polymerase in both bacteria & eukaryotes
Term
acridine
Definition
inhibits RNA synthesis
Term
rifampicin
Definition
inhibits bacterial RNA synthesis by binding to the beta subunit of bacterial RNA polymerases, preventing the promoter clearance step of transcription
Term
alpha-amanitin
Definition
disrupts mRNA formation in animal cells by blocking Pol II & Pol III (at higher concentrations)
Term
ribozymes
Definition
catalytic RNAs
Term
primary transcript
Definition
a newly synthesized RNA molecule
Term
RNA splicing
Definition
introns are removed from the primary transcript & exons are joined to form a continuous sequence that specifies a functional polypeptide
Term
5' cap
Definition
found in most eukaryotic mRNAs; a residue of 7-methylguanosine linked to the 5'-terminal residue of the mRNA through an unusual 5',5'-triphosphate linkage
Term
What is the relationship between spliceosomal introns & spliceosome?
Definition
Spliceosomal introns go through removal that occurs within & is catalyzed by a large protein complex called a spliceosome
Term
small nuclear RNAs (snRNAs)
Definition
100 to 200 nucleotide long eukaryotic RNAs, one of which is in each snRNP
Term
poly(A) tail
Definition
a string of 80 to 250 A residues at the 3' end of most eukaryotic mRNAs
Term
polyadenylate polymerase
Definition
adds A residues after cleavage generates the free 3'-hydroxyl group that defines the end of the mRNA
Term
preribosmal mRNAs
Definition
precursors that make ribosomal RNAs of bacterial, archaeal, & eukaryotic cells; AKA pre-rRNAs
Term
snoRNPs
Definition
snoRNA-protein complexes; consists of a snoRNA & four or five proteins (including the enzyme that carries out the modification)
Term
microRNAs (miRNAs)
Definition
a special class of RNAs involved in gene regulation
Term
internal guide sequence
Definition
a segment that allows the intron to be very precise in its excision reaction; can base-pair with exon sequences near the 5' splice site
Term
exosome
Definition
a complex of up to 10 conserved 3'-->5' exoribonucleases in all eukaryotes; involved in the processing of the 3' end of rRNAs, tRNAs, & some special-function RNAs (as well as the degradation of mRNAs)
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