Quiz

Q1: Which organelle is the destination for destruction of cellular proteins ?

Answer: Lysosome. The proteins that are either aged or misfolded are sent to lysosome for degradation. Lysosome with the help of acidic environment and proteases degrade protein into the smaller peptide. In addition, bacteria or other pathogenic organism also follows the same path to degrade into smaller pieces for antigen presentation in immune cells. Besides lysosome mediated protein degradation, proteins targeted for degradation are also sent to the proteasome complex. Proteasome complex is a non-membranous multimeric protein complex present in cytosol as free particles and they identify and degrade aged and misfolded proteins. [Student can refer to following article for further details of proteasome: Structural biology of the proteasome . Annu Rev Biophys . 2013;42:29-49. doi: 10.1146].

Q2: Which organelle can be visualzed by basic dye Hematoxylin ?

Answer: Nucleus. Nucleus contains genomic DNA (deoxy-ribonucleic acid) and then internal pH is acidic. As a result hematoxylin concentrates into the nucleus and visualize genomic DNA. It can also stain circular DNA in mitochondria but sensitivity of the dye is not optimal for visualization of mitochondrial DNA.

Q3: Treatment of mitochondria with molecule X destroys the proton gradient. These molecular are called as ………………………………………………….

Ans: Uncoupler. The electron transport chain consists of 4 complexes involved in relaying electron and complex V for harvesting proton gradient. Any molecule which can destroy the membrane permeability via making pores will eventually destroy the protein gradient and ultimately affects the ATP production.

Q4. Decribe the structural details of the molecular complex responsible for harvesting proton gradient in the mitochondria?

Ans: ATP Synthase. Please go through the structural details of ATP synthase from web and attempt to collect the information to describe the structure of ATP synthase.