Plant Biology IIT JAM Biotechnology One Shot Revision 2025 | Don’t Miss Out!

[@jahan.3631]

Mam apne jo pdaya ye sare topics mai. Neet ki preparation me ncert class. 11th se pd chuka hu.

[@bhumikasachdev9441]

Ma'am I have a doubt from a pyq: Chloroplast contains thylakoid membrane in which the apparatus for photosynthesis is embedded. The lumen of cytosol also contains proteins. If a protein is translated in the cytosol and its final destination is thylakoid lumen, it has to be transferred across how many membranes? Answer is 2 I'm confused in that because chloroplast is a double membrane bound structure and thylakoid also contains a membrane. If a protein has to reach the thylakoid lumen won't it require to cross three membranes (two of chloroplast and one thylakoid membrane)?

[@ruchitatodkar2192]

A protein that is translated in the cytosol and destined for the thylakoid lumen must be transferred across three membranes: The outer membrane of the chloroplast: Proteins are first transported into the chloroplast, which is surrounded by this membrane. The inner membrane of the chloroplast: After passing through the outer membrane, the protein must then cross the inner membrane. The thylakoid membrane: Finally, the protein must be transferred into the thylakoid lumen by crossing the thylakoid membrane.

[@bhumikasachdev9441]

@ruchitatodkar2192 Thank you so much ma'am for clearing. It was asked in JNU 2015 and in official answer key it is given as 2 so if now it is asked the answer should be 3 right.

[@ruchitatodkar2192]

Layer 3 hoti hai, magar membrane ki baat krte answer 2 is correct because 1) chloroplast ki membrane aur 2) thylakoid membrane

[@bhumikasachdev9441]

@@ruchitatodkar2192 Okay ma'am thank you for clearing