tRNA Flashcards
why might tRNA isoacceptor shifts occur during disease pathogenesis?
cancer cells experience metabolic stresses. ones such as hypoxia nad oxidative stress have been shown to change specific tRNA pools
who discovered souble RNA that ended up being tRNA?
Hoagladn and Zamecnik
how many parts of the tRNA life cycle are there?
3
what are the 2 types of tRNA processing before they reach their final form?
addition of CCA to the 3’ end and nucleoside modifications
what perfroms the 5’ trimming of bacterial tRNAs?
endonuclease Rnase P
how many regions does tRNA fold into?
4
what does tRNA really do?
forms a link between the mRNA and the correct amino acid
what is the anticodon segment of the anticodon loop for?
base pair with the codon in the mRNA
what is the orientation of the tRNA loop?
The longer side is the 3’ end
what does the free 3’ and 5’ ends base pair to form?
acceptor stem
waht is the conserved trinucleotide?
5’-CCA-3’
what is CCA needed for?
needed to maintain and repair the 3’ ends of tRNAs
what are the characteristics of the CCA adding enzyme?
Does not use a template
It contains a nucleotide binding pocket that can accept CTP or ATP
The size and shape of the pocket changes depending on the 3’ end of the tRNA substrate
Plays a role in targeting unstable tRNAs for degradation
Unstable tRNAs acquire CCAs
Small RNAs with multiple CCAs are rapidly degraded
what was the T loop named for?
where is it loacted?
3’ side - named for occurrence of ribothymidine and pseudouridine
what was the D loop named for?
where is it loacted?
5’ side - named after dihydrouridine
where is the wobble position?
5’ side of anticodon - often has inosine
what is the hypermodified purine?
occurs just 3’ to prevent it from base-pairing improperly with the codon in mRNA, thereby helping to align the codon and anticodon properly - 3’ side before anticodon
what is a wobble pairing>
the first 2 positions on the mRNA are read by strict watson crick base pairing with positions 2 and 3 of the anticodon, when the first position is matched to the 3rd position of the codon, non-watson crick pairs are allowed. Means you don’t really need more than 2 tRNA anticodons to decipher 4 codons
