2. RNA (Ribonucleic Acid):
• RNA is much more abundant than DNA
• There are several important differences between RNA and DNA.
• The pentose sugar in RNA is ribose, in DNA it’s deoxyribose.
• In RNA, uracil replaces the base thymine (U pairs with A).
• RNA is single stranded while DNA is double stranded.
3.
4. SPLICING:
• The process of cutting the pre-mRNA to remove the introns and joining together of
the exons is called splicing.
• TAKES PLACE: “in the nucleus”.
• INTRONS: “non-coding sequences”.
• EXONS: “coding sequences”.
6. Self splicing:
• Introns are able to excise itself precisely from the RNA precursor without the
involvement of any proteins.
• specified by the intron RNA itself.
• Doesn’t require snRNp’s.
7.
8. SNRNP PARTICLES: SNRNA + PROTEINS
• Eukaryotic nuclei contain many discreet small RNA species called small nuclear
RNAs (snRNAs) are rich in the base uracil, which complex with specific proteins to
form snRNPs.
• The most abundant snRNP are involved in pre-mRNA splicing are :
• U1
• U2
• U4
• U5
• U6.