Ribosomes

Ribosomes Definition

“Ribosomes are complex cell organelles made of RNA and protein that translates genetic code into chains of amino acids.”

What are Ribosomes?

The ribosome is a complex molecular machine found inside the living cells that make proteins from amino acids in the process called protein synthesis or translation. Protein synthesis is a major task performed by living cells.

Ribosomes are special organelles as they are found in both prokaryotic and eukaryotic cells. Every cell needs ribosomes to manufacture proteins.

It binds to a messenger ribonucleic acid (mRNA) and decodes the information carried by the nucleotide sequence of the mRNA. The transfer RNAs (tRNAs) containing amino acids enter the ribosome at the acceptor site. When it binds correctly, it adds amino acid to the growing protein chain on tRNA.

Also Read: Cell Organelles

Ribosomes Structure

A ribosome is a complex of RNA and protein and is, therefore, known as a ribonucleoprotein. It is made up of two subunits. The smaller subunit is where the mRNA binds and is decoded. While the larger subunit is where the amino acids get added. Both of the subunits are made up of both protein and ribonucleic acid components.

The two subunits are joined to each other by interactions between the rRNAs in one subunit and proteins in the other subunit.

Ribosomes are located inside the cytosol found in the plant cell and animal cell.

The ribosome structure includes the following:

  • It is located in two areas of cytoplasm.
  • Scattered in the cytoplasm.
  • Prokaryotes have 70S ribosomes while eukaryotes have 80S ribosomes.
  • Around 62% of ribosomes are comprised of RNA, while the rest is proteins.
  • The structure of free and bound ribosomes is similar and is associated with protein synthesis.

Ribosomes Function

The important ribosome function includes:

  1. It assembles amino acid to form proteins that are essential to carry out cellular functions.
  2. The DNA produces mRNA by the process of DNA transcription.
  3. The mRNA is synthesised in the nucleus and transported to the cytoplasm for the process of protein synthesis.
  4. The ribosomal subunits in the cytoplasm are bound around mRNA polymers. The tRNA then synthesises proteins.
  5. The proteins synthesised in the cytoplasm are utilised in the cytoplasm itself, the proteins synthesised by bound ribosomes are transported outside the cell.

Also Read: Cells

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Frequently Asked Questions

What is the function of the ribosome?

Ribosomes are the organelles that help in protein synthesis. Protein is required for many cell activities such as damage repair and other chemical processes.

What is a ribosome composed of?

A ribosome is composed of two subunits:

  • the small ribosomal subunits- these read the mRNA
  • the large ribosomal subunits- they form polypeptide chains of amino acids.

How does the ribosome work?

The ribosomal subunits come together and combine with the mRNA during protein synthesis. They bind to the mRNA and start the synthesis of proteins.

What are the two different types of ribosomes?

The two different types of ribosomes include:

  • 70 S-found in prokaryotic cells
  • 80 S-found in eukaryotic cells

How are prokaryotic ribosomes different from eukaryotic ribosomes?

Prokaryotic ribosomes include three separate rRNA molecules whereas eukaryotic ribosomes comprise four separate rRNA molecules. Prokaryotic ribosomes contain the small ribosomal subunit (70S), whereas, eukaryotic ribosomes contain the large ribosomal subunit (80S).

Further Reading:

Thymus

Germ Theory of Disease

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