Ribosomes

Ribsomes Composition:

Ribosomes are made of proteins and rRNA (ribosomal RNA)

These 2 components form a complex that reads mRNA to make proteins

Roles: ribosomes read RNA (mRNA), they build proteins by linking amino acids together

80s ribosomes

Eukaryotic ribosomes, found in eukaryotic cytosol, RER, outer membrane of nucleus

Subunits: 60s large, 40s small

70s Ribosomes

In prokaryotic and eukaryotic mitochondria and plastids,

found in prokaryotic cytosol (bacteria), mitochondria (in eukaryotes), plastids (chloroplasts in plants)

Subunits: 50s and 30s

Ribozymes

Special pieces of RNA that act like enzymes, found in large ribosomal subunit

Role: link amino acids together during protein synthesis, this means RNA does catalysis inside a ribosome

Polysomes/Polyribosomes

A group of ribosomes all attached to the same mRNA strand, allows cell to make lots of copies of a protein very quickly

Xtra notes

Ribozyme= peptidyl transferase centre = rRNA, i.e they are made of nucleic acids

Svedberg units are sedimentation behaviour in a centrifuge