Ribosome Structure and Function

Ribosome Structure

• A ribosome consists of two subunits: one large and one small, each made up of RNA and proteins.
• Eukaryotic ribosomes are found in the cytoplasm and mitochondria, while cytoplasmic ribosomes can be free or attached to the endoplasmic reticulum.
• Ribosomes are not bounded by a membrane.

Ribosome Types

• Prokaryotic ribosomes are smaller and less dense than eukaryotic ribosomes.
• Eukaryotes have 80S ribosomes, with a small subunit of 40S and a large subunit of 60S.
• Prokaryotes have 70S ribosomes, with a small subunit of 30S and a large subunit of 50S.

tRNA Binding Sites

• The ribosome has three sites for binding tRNA: the Peptidyl (P) site, the Aminoacyl (A) site, and the Exit (E) site.

Ribosome Biogenesis

• The nucleolus is the site of synthesis of rRNA.
• The 18S, 5.8S, and 28S RNAs are synthesized in the nucleolus, while the 5S RNA is synthesized on the chromosome outside the nucleolus.
• Ribosomal proteins are synthesized in the cytoplasm and translocated to the nucleolus, where they become associated with the ribosomal subunits.

Ribosome Function

• Ribosomes are responsible for protein synthesis through the translation of mRNA.
• They read the genetic information encoded in mRNA molecules and use it to assemble amino acids into polypeptide chains.
• The ribosome is recycled after protein synthesis, with the two subunits dissociating and being reused when needed.

Learn about the cell's protein synthesis factory, including the composition and function of ribosomes in eukaryotic organisms. Discover the different types of ribosomes and their locations within the cell.