Ribosome: Difference between revisions
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A ribosome is the particle upon which mRNA from DNA transcription is translated to a polypeptide with a specific amino acid sequence defined by the genetic code. It is comprised of 2 subunits: | A ribosome is the particle upon which mRNA from DNA transcription is translated to a polypeptide with a specific amino acid sequence defined by the genetic code. It is comprised of 2 subunits: | ||
30S unit: This is the smaller unit which | 30S unit: This is the smaller unit which consists of 21 proteins and a 16S RNA molecule | ||
50S unit: This is the larger unit which | 50S unit: This is the larger unit which consists of 34 proteins and 2 RNA molecules, 23S and 5S<ref>Berg JM, Tymoczko JL, Stryer L: Biochemistry 6th (2007), WH Freeman and Company, New York. Pg 866</ref> | ||
The 2 units together form the complete ribosome, known as the 70S unit. S refers to the Svedberg unit, which is a measure of rate at which a compound moves when centrifuged. | The 2 units together form the complete ribosome, known as the 70S unit. S refers to the Svedberg unit, which is a measure of rate at which a compound moves when centrifuged. It is used as a measure of size of a molecule but is not directly proportional to molecular weight.<ref>Berg JM, Tymoczko JL, Stryer L: Biochemistry 6th (2007), WH Freeman and Company, New York. Pg 76</ref> | ||
As ribosomes contain RNA (also referred to as ribosomal RNA-rRNA) and | As ribosomes contain RNA (also referred to as ribosomal RNA-rRNA) and proteins, they are also referred to as ribonucleoproteins. Ribosomes translate mRNA in triplets (codons) by alligning complementary triplets found in tRNA molecules (anticodons). Each tRNA is assigned a specific anticodon and amino acid and therefore translation leads to the formation of a protein by forming peptide bonds between adjacently aligned amino acids.<ref>Berg JM, Tymoczko JL, Stryer L: Biochemistry 6th (2007), WH Freeman and Company, New York. Pg 872</ref> | ||
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Revision as of 12:33, 29 November 2010
A ribosome is the particle upon which mRNA from DNA transcription is translated to a polypeptide with a specific amino acid sequence defined by the genetic code. It is comprised of 2 subunits:
30S unit: This is the smaller unit which consists of 21 proteins and a 16S RNA molecule
50S unit: This is the larger unit which consists of 34 proteins and 2 RNA molecules, 23S and 5S[1]
The 2 units together form the complete ribosome, known as the 70S unit. S refers to the Svedberg unit, which is a measure of rate at which a compound moves when centrifuged. It is used as a measure of size of a molecule but is not directly proportional to molecular weight.[2]
As ribosomes contain RNA (also referred to as ribosomal RNA-rRNA) and proteins, they are also referred to as ribonucleoproteins. Ribosomes translate mRNA in triplets (codons) by alligning complementary triplets found in tRNA molecules (anticodons). Each tRNA is assigned a specific anticodon and amino acid and therefore translation leads to the formation of a protein by forming peptide bonds between adjacently aligned amino acids.[3]