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Right option is (C) Plus-end of MICROFILAMENTS

The BEST I can explain: The DRUG cytochalasin is obtained from a mold. It blocks the plus-ends of microfilaments (actin filaments) and CAUSES depolymerization at the minus-end.

The correct answer is (a) True

For EXPLANATION: Unlike microtubules and microfilaments, intermediate filaments lack POLARITY and bothe the ends of the filaments are same in nature.

The CORRECT option is (a) heterogenous

Explanation: Unlike MICROFILAMENTS and MICROTUBULES, intermediate FILAMENTS are CHEMICALLY heterogenous, encoded by 70 different types of genes.

The correct ANSWER is (a) POLARITY

The BEST I can explain: All protofilaments of a MICROTUBULE have the same polarity, with alpha-tubulin at one end and beta-tubulin at the other. The entire polymer of microfilament is POLAR in nature.

The correct answer is (a) nonmuscle cells

For explanation I would say: Myosin II filaments are HIGHLY STABLE in the contractile apparatus of skeletal muscle cells. However in nonmuscle cells they often exhibit transient construction, assembling when required and disassembling after action.

Correct choice is (d) neurodegenerative disorders

Easiest explanation: Neurofilaments are the intermediate FILAMENTS that CONSTITUTE mature neuronal cells. AGGREGATION of these neurofilaments blocks AXONAL transport, associated with neurodegenerative disorders like Alzheimer’s and Parkinson’s disease.

The correct OPTION is (d) dynein

Easiest EXPLANATION: Dynein was the first cytoplasmic motor PROTEIN, associated with the microtubules, to be discovered in 1963 as the protein responsible for the MOVEMENT of cilia and flagella.

Right answer is (d) intermediate filaments

Easiest EXPLANATION: Intermediate filaments provide structural SUPPORT to the organelle. They are found in the cytoplasm as WELL as the nucleus of the animal cells.

The CORRECT choice is (a) intermediate filaments

The explanation is: Nucleus is FOUND in all living matter, ALTHOUGH in contrasting morphology. Of the three cytoskeletal elements, intermediate filaments are only found in the animals.

The correct choice is (c) CILIA

For explanation I WOULD say: Bardet-Biedl syndrome (BBS) is caused due to mutations in genes that affect the assembly of cilia and basal bodies. As result patients suffer with a RANGE of ABNORMALITIES.

Correct OPTION is (a) True

For explanation: Cilia and flagella are ESSENTIALLY the same motile structures that project from surface of many cells. Depending upon the cell type and PATTERN of movement, the term cilia or flagella maybe used.

The correct answer is (B) 2

The best EXPLANATION: Eukaryotic cells have many DIFFERENT types of kinesins and MYOSINS, whereas there are only TWO types of cytoplasmic dyneins present. Out of which one is responsible for most of the transport activities that take place inside the cell.

Right OPTION is (a) proteins

For explanation I would say: The three cytoskeletal elements are polymers of proteins SUBUNITS held TOGETHER by weak, non-covalent bonds. This characteristic construction leads to rapid ASSEMBLY and DISASSEMBLY.

Correct option is (b) 1973

For explanation: Myosin I was discovered in 1973 by THOMAS Pollard and Edward Korn of the National Institutes of Health. The PROTEIN was EXTRACTED from the PROTIST Acanthamoeba.

Correct choice is (c) Actin filament

To EXPLAIN I WOULD say: The head of the myosin binds to the actin filament and its tail binds and HYDROLYZES the ATP, to drive the myosin motor. The head domains of various myosins are similar whereas the TAILS are highly divergent.

The correct answer is (d) myosin VI

For EXPLANATION: The proteins myosins work as motors in CONJUNCTION with the actin filaments. All myosins move towards the POSITIVE END of the actin filaments, except myosin VI which MOVES toward the minus end.

Right choice is (c) actin

For explanation I would say: Microfilaments are composed of globular SUBUNITS of the PROTEIN actin. The actin monomers polymerize to form flexible helical FILAMENTS, in the presence of ATP.

Correct choice is (a) True

Explanation: DEPENDING UPON the cell type, MICROTUBULES can have a range of stability levels. Microtubules of mitotic spindle and cytoskeleton are labile whereas microtubules of cilia and flagella are STABLE.

Right option is (a) lamins

For explanation: Classes I, II, III and IV of polypeptide SUBUNITS of intermediate filaments are involved in the construction of cytoplasmic filaments. CLASS V, called lamins, are PRESENT as a part of inner lining of the NUCLEUS.

Right choice is (d) axoneme

The explanation: The core of the CILIUM is called axoneme, it contains an array of longitudinally running MICROTUBULES. It USUALLY consists of NINE peripheral doublet microtubules surrounding a central pair of single microtubules.

Right choice is (b) 13

Explanation: There are about 10-15 protofilaments TYPICALLY found in an animal cell. Exclusively in mammals there are 13 protofilaments which WOUND up together to FORM a 24 nm wide cylindrical tubule.

The correct CHOICE is (a) MYOSIN

The best explanation: Irrespective of the CELL type and the role played in it by the MICROFILAMENTS, all the actin filaments interact in a highly specific manner with the protein myosin. It is therefore used for the identification of microfilaments.

The CORRECT option is (c) hydrolyzed

Explanation: Actin units are added to the growing microfilament chain by the USE of ATP. Each Actin subunit BINDS an ATP molecule. This ATP molecule is HYDROLYSED to ADP while the Actin unit is ATTACHED to the chain.

The correct answer is (d) muscle CELLS

To elaborate: Absence of intermediate FILAMENTS desmins makes the muscle cells extremely fragile. Desmin polypeptide plays a key ROLE in maintaining the ALIGNMENT of MYOFIBRILS of the muscle cells.

The correct option is (d) Ncd

For EXPLANATION I WOULD say: Ncd is a protein of Drosophila that BELONGS to the FAMILY of kinesin-14 proteins. These proteins move in the opposite direction (compared to other kinesins), that is, towards the minus of the MICROTUBULES.

The correct answer is (a) phosphorylation

The explanation: Microtubule-associated proteins (MAPs) increase the stability and promote the assembly of MICROTUBULES. Their BINDING activity is controlled by addition and REMOVAL of phosphate GROUPS from particular AMINO acid residues.

Correct choice is (b) sacromeres

Explanation: Hundreds of thin, cylindrical strands called myofibrils. Each myofibril contains repeating CONTRACTILE units, called sarcomeres. The sarcomeres EXHIBIT a BANDING pattern GIVING the MUSCLE cells a striated appearance.

Correct OPTION is (B) proteins

Easiest explanation: Intermediate filaments radiate through the CYTOPLASM of a cell and are interconnected to other cytoskeletal elements through cross-bridges. In most CELLS, these cross-bridges are made up of plectins.

The correct choice is (a) primary cilium

Explanation: Not all CILIA are motile, non-motile cilia, CALLED the primary cilium to PLAY a sensory ROLE and MONITOR the properties of extracellular fluids.

The correct answer is (c) tubulin

The BEST I can explain: COLCEMID is a drug that binds to tubulin SUBUNITS and prevents their use by the cell. It is closely related to NATURAL alkaloid COLCHICINE.

The correct option is (B) MINUS end

Easy EXPLANATION: In an AXON, all microtubules are oriented with their plus ends facing the synaptic terminals and minus ends facing the cell body.

Right option is (C) Myosin

The explanation: Motor proteins are divided into THREE superfamilies: dyneins, myosins and kinesins. Dyneins and kinesins MOVE along MICROTUBULES, and myosins move along microfilaments.

Correct option is (a) KERATIN

Easy explanation: Keratin FILAMENTS are FOUND primary in epithelial CELLS including epidermal cells, liver hepatocytes and pancreatic acinar cells.

The correct choice is (a) chemicals

Easy explanation: INTERMEDIATE filaments are less sensitive to chemical agents and DIFFICULT to solubilize them, although they behave DYNAMICALLY in VIVO.

The correct choice is (a) C. elegans

For explanation: Cilia and basal bodies have an IMPORTANT role in organ development and FUNCTION. MANY of the genes responsible for CILIOPATHIES (cilia-based disorders) were first identified in model organisms C.elegans and CHLAMYDOMONAS.

Right option is (a) True

To explain I would SAY: Plus-END is the faster growing end of the actin FILAMENTS and incorporates actin monomers at a rate 10 times that of the other (minus) end.

Correct ANSWER is (d) IV

To explain I would say: Neurofilaments consist of TYPE IV polypeptide subunits of INTERMEDIATE filaments. Neurofilaments are present in mature NERVE CELLS.

Correct answer is (a) True

The best I can explain: Unlike ANIMAL cells, PLANT cells rely PRIMARILY on microfilaments for long-distance transport of CYTOPLASMIC organelles and vesicles.

The CORRECT answer is (b) FRAP

The best explanation: FLUORESCENCE RECOVERY after photobleaching (FRAP) is a technique that has been used by the researchers to study the dynamic properties of MICROTUBULES. In a FRAP experiment, the cell is either injected with fluorescently labeled tubulin or INDUCED to express GFP-tubulin.