Which of the following synthesize proteins that will remain in the cell as functional elements:
Ribosomes are highly complex structures made up of ribosomal RNA and specific protein. They are first observed under an electron microscope by George Emil palade in the mid-1950s. Ribosomes that are not attached endoplasmic reticulum or any other cell organelles are known as free ribosomes. These ribosomes act as a site for biological protein synthesis. Ribosomes consist of two parts or subunits known as:
i) Small ribosomal subunits that read mRNA and
ii) Large subunit that joins the amino acids to form large polypeptide chains.
Cells with a large number of free ribosomes are basophilic as they produce the proteins that will remain in the cells.
Examples of cells with free ribosomes are:
Red blood cells (hemoglobin)
Developing muscle cells (contractile proteins like actin and myosin)
Nerve cells (neurofilaments) and
Keratinocytes of skin (keratin)
The ribosomes which are attached to endoplasmic reticulum called as rough endoplasmic reticulum synthesize the proteins for export from the cell.