Key Points

• Ribozymes are enzymes formed from RNA instead of proteins.

• Spliceosomes are protein-RNA complexes that catalyze the removal of introns and joining of exons in pre-mRNA strands.

• Spliceosomes are composed of many protein-RNA complexes called snRNPs, which are themselves composed of a specific type of RNA known as snRNA.

Key Terms

Ribozyme: An enzyme formed from RNA instead of proteins.

Enzyme: A molecule that catalyzes (or accelerates) a biochemical reaction.

Spliceosome: A protein-RNA complex that acts as an enzyme during pre-mRNA processing to remove introns and join together exons.

Small nuclear ribonucleoproteins (snRNPs): Complexes of protein and RNA that are the building blocks of spliceosomes.

Small nuclear RNAs (snRNAs): Nuclear RNAs that make up the RNA component of snRNPs.