Question

Explain Ribosme's Structure in Prokaryotic(70S) and Eukaryotic cells(80S) ?

Answer 1

Structure of Prokaryotic ribosome

Prokaryotic ribosome’s are 20nm in diameter and are made up of about 65 percent of rRNA and 35 percent ribosomal proteins. Prokaryotes have 70S ribosome’s which are made up of a smaller 30S subunit with a molecular weight of 1.0 X 10⁶ and a larger 50S subunit with a molecular weight of about 1.8 X 10⁶. The small subunit has 16S RNA which consists of about 1540 nucleotides which are bound to 21 proteins. The larger subunit is made up of 5S RNA having about 120 nucleotides, one 23S RNA subunit with 2900 nucleotides and has 31 proteins. Their sedimentation co-efficient is 64S to 72S. The RNA to protein ratio is 2:1

Structure of Eukaryotic ribosome

Eukaryotic ribosome’s are 25 to 30 nm in diameter. Eukaryotic ribosomes have one to three very large molecules of rRNA and many small molecules of protein. Eukaryotes have 80S ribosome’s which are made up of a smaller 40S subunit with a molecular weight of 1.3 X 10⁶ and a larger 60S subunit with a molecular weight of 2.7 X 10⁶.The 40S subunit has 18S RNA with 1900 nucleotides and 33 proteins . The large 60S subunit is made up of 5S RNA with 120 nucleotides with 4700 nucleotides, and a 5.8S RNA with 160 nucleotides and 46 proteins. Their sedimentation co-efficient is 79S to 85s in fungi and 80s in higher plants and animals. The RNA to protein ratio is 1:1.