Ribosomes – Structure and Functions

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Ribosomes are a cell structure that makes protein. Protein is needed for many cell functions such as repairing damage or directing chemical processes. Ribosomes can be found floating within the cytoplasm or attached to the endoplasmic reticulum.

The location of the ribosomes in a cell determines what kind of protein it makes. If the ribosomes are floating freely throughout the cell, it will make proteins that will be utilized within the cell itself. When ribosomes are attached to endoplasmic reticulum, it is referred to as rough endoplasmic reticulum or rough ER. Proteins made on the rough ER are used for usage inside the cell or outside the cell.

ribosome

Structures of Ribosomes

  • Situated in two areas of the cytoplasm.
  • They are seen scattered in the cytoplasm and a few are connected to the endoplasmic reticulum.
  • Whenever joined to the ER they are called the rough endoplasmic reticulum.
  • The free and the bound ribosomes are very much alike in structure and are associated with protein synthesis.
  • Around 37 to 62% of RNA is comprised of RNA and the rest is proteins.
  • Prokaryotes have 70S ribosomes respectively subunits comprising the little subunit of 30S and the bigger subunit of 50S.
  • Eukaryotes have 80S ribosomes respectively comprising of little (40S) and substantial (60S) subunits.
  • The ribosomes seen in the chloroplasts of mitochondria of eukaryotes are comprised of big and little subunits composed of proteins inside a 70S particle.
  • Share a center structure which is very much alike to all ribosomes in spite of changes in its size.
  • The RNA is arranged in different tertiary structures.
  • The RNA in the bigger ribosomes is into numerous continuous infusions as they create loops out of the center of the structure without disturbing or altering it.
  • The contrast between those of eukaryotic and bacteria are utilized to make antibiotics that can crush bacterial disease without damaging human cells.

Functions of Ribosomes

  1. They assemble amino acids to form specific proteins, proteins are essential to carry out cellular activities.
  2. The process of production of proteins, the deoxyribonucleic acid produces mRNA by the process of DNA transcription.
  3. The genetic message from the mRNA is translated into proteins during DNA translation.
  4. The sequences of protein assembly during protein synthesis are specified in the mRNA.
  5. The mRNA is synthesized in the nucleus and is transported to the cytoplasm for further process of protein synthesis.
  6. In the cytoplasm, the two subunits of ribosomes are bound around the polymers of mRNA; proteins are then synthesized with the help of transfer RNA.
  7. The proteins that are synthesized by the ribosomes present in the cytoplasm are used in the cytoplasm itself. The proteins produced by the bound ribosomes are transported outside the cell.

Image Source:
http://faculty.southwest.tn.edu/rburkett/Cell%20s19.jpg