Question

Porins are
(a) Polysaccharides
(b) Proteins
(c) Nucleic acid
(d) Bacteria

Answer 1

Hint: Porins are pores that are water-filled and channels present in the membranes of eukaryotes and bacteria. Porin is made up of beta- sheets. The structure of the porin molecule consists of amino acids that act as essential nutrients for the human body.

Complete answer:
- Porins are beta-barrel proteins. They cross a cell membrane and act as a pore through which molecules can spread.
- Porins are large enough, unlike other membrane transport proteins, to allow passive diffusion, i.e. they serve as channels unique to different types of molecules.
- Porins are generally present in the gram- negative bacteria and some gram- positive mycobacteria (mycolic acid-containing actinomycetes), the outer mitochondrial membrane, and the outer chloroplast membrane.
- Porins are mainly involved in the passive transport of hydrophilic molecules through the membrane of different sizes and charges. Certain necessary nutrients and substrates must be transported into the cells for survival. To prevent chemical accumulation, toxins and waste must also be transported outside. Porins can also control permeability and avoid lysis by limiting the entry of detergents into the cell.
So, the correct answer is, ‘Proteins’.

Note:
- Porins consist of beta- sheets consisting of beta strands connected together by beta turns on the cytoplasmic side and by long amino acid loops on the other side.
- Porin- like channels were also found in Archaea. Note that the term 'nucleoporin' refers to unrelated proteins which, in the nuclear envelope, facilitate transport through nuclear pores.
- Many porins are targets for host immune cells, contributing to signaling pathways contributing to the degradation of bacteria. To supplement this immune response, therapeutic treatments, such as vaccinations and antibiotics, are used. Specific antibiotics have been designed to travel through porins in order to inhibit cellular processes.