Which of the following is true? Proteins destined to be imported into mitochondr
ID: 205764 • Letter: W
Question
Which of the following is true?
Proteins destined to be imported into mitochondria, peroxisomes, chloroplasts and the nucleus each carry special sequences that help them to be targeted to their correct destination.
Proteins targeted to mitochondria and chloroplasts must carry multiple targeting signals so that they become localized to the proper compartment of each organelle.
Lysosomes act as "digestive systems" for cells.
All of the above are true.
A)Proteins destined to be imported into mitochondria, peroxisomes, chloroplasts and the nucleus each carry special sequences that help them to be targeted to their correct destination.
B)Proteins targeted to mitochondria and chloroplasts must carry multiple targeting signals so that they become localized to the proper compartment of each organelle.
C)Lysosomes act as "digestive systems" for cells.
D)All of the above are true.
Explanation / Answer
Answer=
D]All of above are true
explaination=
A]Proteins destined to be imported into mitochondria, peroxisomes, chloroplasts and the nucleus each carry special sequences that help them to be targeted to their correct destination.
most of the mitochondrial precursor proteins have a signal sequence at their N-terminus that is rapidly removed after import by a protease
protein translocation across mitochondrial membranes is mediated by multisubunit protein complexes that function as a protein translocators.
TOM complex functions across the outer membrane & 2 TIM complexes TIM23 & TIM22 functions across the inner membrane .
The preprotein for chloroplast may contain a stromal import sequence or stromal or thylakoid targetting sequence.
proteins translocated to peroxisomes contains peroxisome targetting sequence.
PTS 1 =a C terminal tripeptide with a consensus sequence.
PTS2 = a nonapeptide located near the Nterminus with a consensus sequence.
B] Proteins targeted to mitochondria and chloroplasts must carry multiple targeting signals so that they become localized to the proper compartment of each organelle.
protein translocation across mitochondrial membranes is mediated by multisubunit protein complexes that function as a protein translocators.
TOM complex functions across the outer membrane & 2 TIM complexes TIM23 & TIM22 functions across the inner membrane .
proteins translocated across choloroplast are translocated through Toc and Tic complexes located within the chloroplast envelope.
C]Lysosomes act as "digestive systems" for cells.
lysosomes are double membrane bound organelles that contains an array of enzymes capable of breaking down all types of biological polymers,proteins,nucleic acids,carbohydrates and lipids.
lysosomes functions as digestive system of cell,serving both to degrade material taken up from outsidethe cell & to digest.
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