G-actin subunits that polymerize form microfilaments, also known as actin filaments. The other cytoskeletal components listed are formed from different proteins, but only microfilaments are actin-based structures. 

Tubulin is a key protein found in microtubules. Microtubules are large cytoskeletal elements that have several functions inside a cell. One of the biggest use of microtubules arises during mitosis. Recall that chromosomes are pulled apart to opposite ends during the anaphase of mitosis. The rope-like substances that pull these chromosomes to opposite ends of cell are microtubule segments. In addition, microtubules are also involved in axonal transport in neurons. Some nerves (such as sciatic nerve) can have extremely long axons. To maintain the integrity of these distal ends of the axons, nutrients and other important molecules from the cell body of a neuron are carried, along microtubule segments, to axon terminals; therefore, microtubules are also essential for axonal transport.

Recall that tubulin is an essential component of microtubules. Administering Vincristine to cancer patients will halt the synthesis of microtubules in cancer cells, thereby inhibiting several essential cellular processes (such as mitosis). This will prevent proliferation of the cancer cells. There are three cytoskeletal elements; microtubules, microfilaments, and intermediate filaments. Of the three, microtubules are the biggest, followed by intermediate filaments. Recall that microtubules are also involved in axonal transport in neurons; therefore, halting microtubule synthesis in neurons could result in nerve problems and neuropathies.

Actin-myosin interactions involved in muscle contraction do not depend on the microtubules; therefore, Vincristine will not affect muscle contraction. Note that actin filaments make up microfilaments; therefore, any damage to actin (and microfilaments) will affect muscle contraction.

Microfilaments are the smallest of the three cytoskeletal elements and are made up of actin filaments (myosin is not found in microfilaments). The 9+2 arrangement is found in microtubules, the biggest cytoskeletal elements. The third cytoskeletal element is called the intermediate filament and is made up of related proteins unique to each intermediate filament.

The contractile ring formed during cytokinesis is composed of actin microfilaments (a component of the cytoskeleton) and the motor protein myosin. The extracellular matrix can be anchored to the cell via the actin cytoskeleton or the intermediate filament cytoskeleton, via adherens junctions or desmosomes.

Post-translational modifications of proteins commonly occur in the endoplasmic reticulum or the Golgi apparatus and do not involve the cytoskeleton. The same logic applies for post-transcriptional modifications of mRNA, except these occur in the nucleus. 

Eukaryotic flagella are primarily composed of microtubules and the motor protein dynein. Hydrolysis of ATP by dynein produces a sliding movement of the microtubule filaments that produces movement.

Kinesin is a motor protein that associates with microtubules, but it is not present in flagella. Myosin is a motor protein that associates with actin microfilaments. 

Cilia, microvilli, and flagella are all protrusions from the cell body. Cilia and flagella have functions in cell motility and contain organized systems of microtubules and motor proteins. Microvilli are often used as mechanosensors and are primarily made of cross-linked actin filaments. Microtubules are, therefore, found primarily in cilia and flagella, but no in microvilli.

Flagella are long, hair-like extensions of the plasma membrane. The movement of flagella propel some cells through fluid.

Mitochondria are the site of the reactions of aerobic metabolism and ATP synthesis. Centrioles consist of microtubules at the base of cilia and flagella, and are involved in spindle cell formation during cell division. The cytoskeleton is a network of protein fibers in the cytoplasm that give shape to a cell and is typically involved in cell movement. A pilus is a hair-like projection located on the surface of certain bacteria and is typically used to attach a bacterium to another cell.

Acid hydrolases are proteins that are specifically designed to function at acidic pH, particularly at levels that would typically denature other proteins. They are commonly found in lysosomes where they aid in the digestion of various cellular wastes and materials.

Though acid hydrolases use water to break apart molecules, acids are not used as reactants, products, or catalysts in these reactions.

An acidic environment is not suitable for the cell as a whole, so the low pH is sequestered in a specific organelle: the lysosome. This low pH in the lysosome activates the hydrolytic enzymes in the lysosome, and allows them to degrade macromolecules that enter the organelle.