DNA vs RNA (lecture 17) Flashcards
what does every species have in common?
DNA as an information store in the form of genes
RNA as a messenger
protein as the major cellular catalyst
LUCA had these properties
what is the central dogma?
DNA to RNA to protein
function of DNA
storage of genetic information
functions of RNA
store of genetic information carrier of genetic information recognition catalytic activity temperature structure scaffolding
how is RNA different to DNA?
uracil instead of thymine
2’ OH - makes RNA unstable but also increases its chemical stability
RNA is a single strand
activities of RNA in cells
ribozymes binding small molecules & changing conformation pre mRNA splicing tRNAs and rRNAs regulation of translation organisation and maintain ace of DNA
what are introns?
non coding parts
they do not self splice
their excision is catalysed by the splicosome
what is a hammerhead ribozyme?
found in virusoids
some plant viruses package small RNAs (virusoids) in addition to their genomic DNA
virusoids replicate by a ‘rolling circle’ mechanism, the ribozyme separates the replicating strand into single lengths
what does the hammerhead ribozyme target?
mRNAs encoding virus receptors
viral RNAs
mRNAs encoding determinants of malignancy in cancers
what is SELEX?
Systematic Evolution of Ligands by EXponetial enrichment
example activities shown for RNA using SELEX
template dependent RNA polymerisation ligation of 2 RNAs together Diels-Alder reaction - cycloaddition Micheal addition - C-C bond formation S-alkylation phosphorylation C-N bond formation
what are aptamers?
molecules that bind to specific targets
what can RNA aptamers be used for?
biosensors
drug targeting agents
gene regulation
arguments in favour of the RNA world
RNA is used for information storage and catalysis
simpler to suggest a single molecule replicating itself
could plausibly evolve into modern day biology
