Role of Ubiquitin in cell -

Ans. is 'c' i.e., Energy dependent protein degradation o There are two major enzyme systems responsible for degradation of damaged or unneeded proteins1) Ubiquitin-proteosome proteolytic pathway# Defective protein is first covalently attached to ubiquitin. Covalent bond is formed between glycine (a- carboxyl group) of ubiquitin and lysine (amino group) of target protein.# Ubiquitinated protein is then degraded in proteosomes by ATP dependent (energy dependent) mechanism.2) Lysomes# Proteins are degraded by proteolytic enzymes which is energy independent (non-energy dependent).