Question

Membrane proteins may function in protein manufacture. amphipathic modification. information storage. ( receiving extracellular signals. temperature control.

Answer 1

1. Membrane proteins function- receiving extracellular signals

Membrane proteins are proteins present on surface of cell membrane.They act as receptors for various hormones, drugs, signals etc. The main functions of membrane proteins involve-

* enzymatic action by acting as receptors

*transport of molecules across cell membrane

*signal transaction process

* Intercellular attachments

*Recognition of similar cells

2. 70S, 50S, 30S, 80S, 60S, 40S

*Prokaryotic ribosomes are of 70 S type where the S represents Sedimentation coefficient.It is composed of 2 subunits- a larger 50S subunit and a small 30S subunit. These ribosomes are involved in the process of protein synthesis. 50S subunit contains 5S RNA and 23S RNA while 30S part contains 16S RNA. 70S ribosomes are also found in mitochondria of eukaryotes.

*Eukaryotic ribosomes are of 80S type composed of larger 60S subunit and small 40S subunit. They are present on rough endoplasmic reticulum and freely on cytosol as well. 60S subunit contains 5S RNA, 5.8S RNA and 28S RNA while 40S subunit contains 18S RNA.