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Right CHOICE is (a) protein

The best explanation: ‘Niemann^–Pick TYPE C disease’ is an inherited disorder in which a protein required to transfer cholesterol out of the lysosomes is lacking. Consequently, cholesterol is ACCUMULATED in these ORGANELLES leading to nerve degeneration.

Right option is (c) pH

Best EXPLANATION: TRANSFORMATION from an early endosome to a LATE endosome is characterized by a decrease in the pH and a MAJOR change in the internal morphology of the structure.

Correct answer is (b) False

The explanation is: The residual bodies FORMED after the DIGESTION of organelles by lysosomes are either discharged from the cell by exocytosis or retained inside the cell, known as ‘lipofuschin granules’. These granules increase in numbers as an individual GROWS OLDER.

Right choice is (a) True

Easiest explanation: Before FUSING with the target site the protein coat is DISASSEMBLED and CONTENTS released in the cytosol. This is triggered by the hydrolysis of GTP BOUND to Sar1.

The correct choice is (c) sialyl-transferase

The explanation is: The ENZYME sialyl-transferase is LOCATED at the trans face of the Golgi STACK and it places sialic acid at the TERMINAL POSITION of the glycoprotein chains.

Right answer is (c) disulfide bonds

The BEST I can explain: Disulfide bonds play an important role in the stability of PROTEINS. When the proteins enter ER LUMEN they contain cysteine RESIDUES in the reduced form (-SH) which is converted to oxidized disulfide bonds (-SS-) when they leave the ER, a reaction catalyzed by protein disulfide isomerase (PDI).

Correct option is (C) PROTEINS

Explanation: The lysosomes PLAY a vital role in digestion and waste removal from the cell. These ORGANELLES are composed of SOLUBLE proteins that carry out this function.

Right answer is (b) stored

To EXPLAIN: In regulated secretion activities of the CELL, materials are stored in MEMBRANE BOUND packages and released only when there is an invoked RESPONSE.

Right CHOICE is (b) False

Explanation: Organelles of the ENDOMEMBRANE system are DYNAMIC in nature and experience a continuous flux while they PERFORM the REGULAR activities inside the cell.

Correct OPTION is (b) False

To elaborate: Endocytosis is the PROCESS where the cell ENGULFS cell surface receptors bound with ligands; whereas phagocytosis is the process where the cell UPTAKES particulate matter.

Right choice is (c) folded to its NATIVE conformation

For explanation: Following its entry into the mitochondrial MATRIX, the unfolded peptide is CONVERTED back to its original folded state followed by the enzymatic removal of its presequence.

Correct choice is (b) osmosis

Best EXPLANATION: Due to high concentration of ions in the vacuole, WATER enters by osmosis. Hydrostatic PRESSURE exerted by the vacuole provides MECHANICAL STRENGTH to the plant cell.

The correct choice is (C) glucocerebrosidase

The EXPLANATION is: Gaucher’s disease is caused by the DEFICIENCY of the lysosomal enzyme glucocerebrosidase. DUE to this deficiency, large quantities of glucocerebroside accumulate in the lysosomes of MACROPHAGES.

The correct ANSWER is (b) ABSENCE of a SINGLE lysosome

The explanation is: Lysosomal storage DISORDERS are caused due to the absence of a single lysosomal enzyme. For example, the ‘Pompe disease’ is caused by the absence of alpha-glucosidase.

Correct choice is (C) DOUBLE membrane

To explain: In autophagy, the organelles of the cell are fused and SUBSEQUENTLY ingested by the lysosomes. Prior to fusion a double membrane wraps up the ORGANELLE to be degraded, forming an autophagosome.

Correct answer is (a) retrograde

To EXPLAIN: The COPI-coated VESICLES transport the materials in retrograde direction; from endoplasmic reticulum (ER) to Golgi stack and from trans Golgi CISTERNAE backward to CIS Golgi cisternae.

Correct answer is (c) 6

Easiest EXPLANATION: The hydrophobic SIGNAL present in the nascent polypeptide is recognized by the SRP which then BINDS to the SRP receptor and transports the PEPTIDE to the endoplasmic reticulum MEMBRANE. The signal recognition particle (SRP) consists of 6 distinct polypeptides and one small 7S RNA.

The correct option is (a) Peroxisomes

To ELABORATE: Proteins carrying a peroxisomal targeting signal (PTS) bind to the PTS receptors, present on the membrane surface, which escort the PROTEIN through the BOUNDARY membrane to the internal MATRIX, in its NATIVE folded state.

Correct choice is (b) bloated

Easy EXPLANATION: In the cells of individuals affected by the ‘I-cell disease’, lysosomes are bloated due to undegraded MATERIALS. This is because the hydrolytic enzymes are not in PROPER conformation.

The correct choice is (c) liver

To elaborate: Kupffer CELLS are PHAGOCYTIC cells situated in the liver which are responsible for engulfing the aging RED BLOOD cells. The lysosomes of these cells have IRREGULAR shape and variable electron density.

The correct option is (a) G-PROTEIN

To elaborate: A protein COAT made of soluble PROTEINS is assembled on the cytosolic surface of the donor membrane at the SITE where budding takes place; this assembly is triggered by the ACTIVATION of G-protein.

Right OPTION is (b) procollagen

The explanation is: Procollagen molecules are the PRECURSORS of extracellular collagen found in FIBROBLASTS. They move from cis cisternae to the trans cisternae without ever LEAVING the cisternal LUMEN.

Correct ANSWER is (c) N-linked oligosaccharides

The best I can EXPLAIN: Pectins and hemicelluloses found in the plant cell wall as well as O-linked oligosaccharides are synthesized completely in the Golgi COMPLEX. The SYNTHESIS of N-linked oligosaccharides begins in the endoplasmic reticulum (ER).

The CORRECT answer is (b) False

Easy explanation: GFP is a fluorescent protein used to tag the protein whose biosynthetic pathway has to be determined. A chimeric of GFP SYNTHESIZING and test protein synthesizing gene is incorporated in the cell. GFP JOINED at the end the protein has absolutely no EFFECT on the protein’s activity or pathway.

Correct choice is (a) Keratin

Easiest explanation: The Golgi complex is mechanically SUPPORTED by a scaffold or a peripheral MEMBRANE skeleton consisting of a variety of PROTEIN families – ankyrin, ACTIN, spectrin.

The correct choice is (B) two

Best explanation: Secretory activities lead to the discharge of proteins synthesized in the ENDOPLASMIC reticulum. There two types of secretory activities of a CELL NAMELY constitutive secretion and regulated secretion.

Correct answer is (a) True

Best explanation: “Pulse-CHASE” is an experiment that LED to elucidation of biosynthetic pathway of the secretory PROTEINS. Pulse was the brief period in which ACINAR cells were incubated in a solution mixture containing radioactively LABELED amino acids and chase is the period when incubation in solution containing unlabeled amino acids is done.

The correct OPTION is (b) SNAREs

Best explanation: SNAREs present on the membranes of synaptic vesicles and PRESYNAPTIC membranes are the only targets of POTENT BACTERIAL toxins; botulism and tetanus. Cleavage of SNAREs by these toxins blocks the release of neurotransmitters and lead to PARALYSIS.

Correct option is (a) True

To explain I would say: Cis-Golgi network is the entry FACE CLOSES to endoplasmic reticulum (ER) and trans-Golgi network is the opposite face to the ER. The CGN primary FUNCTIONS to SORT out the proteins that are to be sent back to ER and those that proceed further in the Golgi complex.

Right choice is (a) mannose phosphorylation

To explain I WOULD say: Mannose 6-phosphate residues are present on the LYSOSOMAL ENZYMES that direct these PROTEINS to the lysosomes after their synthesis from Golgi complex.N-acetylglucosamine phosphotransferase ADDS the mannose residues on lysosomal enzymes.

Correct OPTION is (b) Radioisotopes

Easy explanation: In Autoradiography, cells LABELED with radioisotopes are overlaid with a photographic emulsion that contains silver GRAINS. The labeled ENTITIES can then be viewed under the MICROSCOPE by the silver grain.

Right choice is (C) cytosol

The EXPLANATION: Few of the INTEGRAL membrane polypeptides of the mitochondria are synthesized in mitochondria itself. Most of its PROTEINS (99%) are synthesized in the cytosol and then imported posttranslationally.

The CORRECT option is (d) v-SNARE

Explanation: During the regulated release of neurotransmitters, synaptic vesicles are DOCKED to the PRESYNAPTIC membrane of the NERVE cell. Synaptobrevin is a v-SNARE present on the membrane of a synaptic vesicle.

The correct CHOICE is (a) smooth endoplasmic reticulum

Explanation: Detoxification of organic COMPOUNDS is carried out by the smooth endoplasmic reticulum, chronic use of compounds such as barbiturates and ethanol can LEAD to proliferation of SER in LIVER cells.

Right option is (c) ER, GOLGI complex

The best I can EXPLAIN: COPII-coated vesicles (COP is an acronym for coated PROTEINS) transport the materials from endoplasmic RETICULUM (ER) to ERGIC and Golgi complex.

The correct choice is (a) homogenization

Best EXPLANATION: Subcellular fragmentation is a technique that elucidates the molecular composition of an organelle. The cells are first ruptured by homogenization and as a result their membranes and internal structures get fragmented and form vesicles. Since the vesicles derived from different organelles (like ribosome, ENDOPLASMIC RETICULUM ETC.) have different PROPERTIES, they get separated from one another.

Correct answer is (d) digestion

For explanation I would say: Lysosomes are digestive organelles of a cell and CONTAINS over 50 DIVERSE types of hydrolases. These enzymes work at an acidic pH and can HYDROLYZE MOSTLY all types of biomolecules.

Correct answer is (b) PROTEIN

Best explanation: Clathrin is a protein present on the outer SURFACE of clathrin-coated vesicles FORMING a honeycomb-like lattice. The MAIN function of these vesicles is to transport LYSOSOMAL enzymes.

The correct ANSWER is (a) True

The best I can explain: Worn-out organelles are digested by fusion with the lysosomes and the contents are MADE AVAILABLE to the cell. In a state of nutrient DEPRIVATION the occurrence of autophagy in a cell INCREASES.

Correct option is (b) GTP

Explanation: SIMILAR to Sar1 protein found in COPII-COAT PROTEINS, ARF1 is a GTP-binding protein found in COPI-coat proteins. The GTP is hydrolyzed PRIOR to disassembly of the coat.

Right choice is (c) NUCLEIC acids

To explain I WOULD SAY: The primary function of endoplasmic reticulum is the synthesis of PROTEINS. However certain lipids and cholesterol molecules are also synthesized in ER.

The correct choice is (c) Autoradiography

The best explanation: The acinar cells of the PANCREAS secrete DIGESTIVE enzyme that reach the small intestine and aid in digestion of food. The STEPS INVOLVED in the synthesis of these proteins, migration to cell surface and the subsequent discharge was studied USING autoradiography by James Jamieson and George Palade of Rockefeller University.

Right answer is (d) endosomes

Easiest explanation: Following the internalization of materials from the extracellular ENVIRONMENT to the INTRACELLULAR environment, the VESICLE bound materials are TRANSPORTED to endosomes.

The correct answer is (a) MEMBRANE

Easy explanation: Tonoplast is the membrane that bounds the vacuole. It contains many active TRANSPORT system that pumps IONS into the vacuole.