15. Types Of Rna Flashcards
What is tRNA ?
Transfer Rna
Involved in protein synthesis
Act as carriers to bring amino acids to ribosome
Ensures that amino acid added to chain is the one specified my mRNA
Consist of one single strand of RNA which has complementary segments that stick together to make double stranded religions
What Is rrna
Ribosomal rna - major component of ribosomes
Helps mRNA bind in correct position so it’s sequence info can be read out
Some also act as enzymes - help catalyse chemical reactions ie formation of bonds that link amino acids to protein- ribozymes
What is mRNA
Messenger rna
Intermediate between protein codon gene and it’s product
Associates with ribosome
Helps to assemble proteins out of aa- ribosome uses info in mRNA to make protein of specific sequence- reading out mRNAs nucleotides in groups of three - codons
rRNA
Regulatory rna
Has non coding types which help regulate expression of other genes
MicroRNA
SIRNA
Small about 22 nucleotides long
Bind to specific mRNA mola and reduce their stability or interfere with translation
What is eukaryotic pre mRNA processing?
Pre mRNA - when rna transcript is first made in eukaryotic cell it is considered as this name and must be processed into mRNA
In splicing - some sections of rna transcript- introns are removed- remaining exons are stuck back together
Some genes can be alternately spliced - leading to production of different mature rna from initial transcript
What are introns and exons
Introns - non coding regions - are nucleotide sequences in dna/rna that do not code for portions and are removed by precursor mRNA by rna splicing
Exons - coding regions - nucleotide sequences in dna/ rna that are conserved in the creation of mature rna
What is DNA splicing ?
Occurs during transcription
Introns removed from mRNA molecules in nucleus
Introns always have two nucleotides at either end
5’ splice site GU
3’ AG
Rna processing does not happen in prokaryotes
In bacteria rna transcripts are ready to act as messenger rna and get translated straight away
Describe function of 5 cap
Immediately after rna synthesis innetiation . 5 end of rna is called by methyl guanosine residue which prevents refraction of rna by exonucleases
Also helps transport mRNA out of nucleus
Plays important role in initiation of mRNA translation
What are the 3’ poly a tails
Addition of tail of 200 adenosine monophosphatases to 3’ end of hnrna
Primary transcribe contain conserved aauaaa sequence = polydenylation signal
Which is recognised by specific endo nucleuses that cleaves rna around 20 nucleotides
Compare introns exons
