Tag: zoology

Movement of cilia and flagella in a eukaryotic cell is powered by ATP and these ATP molecules are hydrolysed into ADP+Pi in cilia and flagella by the activation of dynein protein
Nexin protein is found in cilia and flagella and it prevents microtubules from moving
Myosin of muscles- It is found in animals

The body of euglenoids are covered by a thin pellicle, that has oblique but parallelly arranged stripes. It provides it the flexibility to cause temporary changes in body shape. The pellicle strips slide over one another to help in metabolic. So, the correct option is 'Pellicle'.

• A cilium is an organelle found on eukaryotic cells and are slender, small protuberances that project from the much larger cell body.
• It works like oars, causing the movement of the surrounding fluid. They are primarily responsible for locomotion, either of the cell itself or of fluids on the cell surface.
• Hence Cilia are small structures which work like oars, causing the movement of the surrounding fluid is a True statement.
• So, the correct answer is 'True'.

Rhizoplast is a fibril which is a connecting link between blepharoplast, with the nucleus in flagellated cells or organisms. It is a striated contractile structure attached to the basal region of the cilium in a variety of ciliates and flagellates. Many regulate the flagellar beat pattern, and is sensitive to calcium concentration. They are composed of a 20 kD protein, rather similar to spasmin. The ciliary rootlet or rhizoplast, is a cytoskeleton-like structure that originates from the basal body at the proximal end of a cilium. It extends proximally toward the cell nucleus. Rootlets are typically 80-100 nm in diameter and contain cross stria distributed at regular intervals of approximately 55-70 nm. 

So, the correct answer is option C.

A basal body (synonymous with basal granule, kinetosome and in older cytological literature with blepharoplast) is an organelle formed from a centriole, and a short cylindrical array of microtubules. It is found at the base of a eukaryotic undulipodium (cilium or flagellum) and serves as a nucleation site for the growth of the axoneme microtubules. Centrioles, from which basal bodies are derived, act as anchoring sites for proteins that in turn anchor microtubules within centrosomes, and are known as the microtubule organizing center (MTOC).

Centrosome is composed of two centrioles lying at right angles to each other. Each centriole has a cartwheel constitution. There is a whorl of nine peripheral triplet fibres of tubulin tilted at an angle of 40 degrees. In cilia and flagella also the cartwheel structure is present but the fibrils have 9+2 arrangement- peripheral doublet fibrils are tilted at an angle of 10 degrees.

A cilium is an organelle found in eukaryotic cells. Cilia are slender protuberances that project from the much larger cell body. Inside cilia and flagella, is a microtubule-based cytoskeleton called the axoneme. The axoneme of primary cilia typically has a ring of nine outer microtubule doublets (called a 9+0 axoneme) and the axoneme of a motile cilium has two central microtubule singlets in addition to the nine outer doublets (called a 9+2 axoneme). A flagellum is a lash-like appendage that protrudes from the cell body of certain prokaryotic and eukaryotic cells. Flagella also has 9+2 arrangement of microtubules. They both contains inner growth along with outer growth of cytoplasm. They both are not the protective structures.

Vincristin and Vinblastin are important anti cancer drugs, isolated from Althea rosea. These drugs inhibit spindle formation and thus arrest uncontrolled division of cancer cells. Tubulin are important cytoskeletal elements. Actin, Myosin are important for cellular movements. Motor proteins utilizing the cytoskeleton for movement fall into two categories based on their substrates: Actin motors such as myosin move along microfilaments through interaction with actin.