Cell Biology Test - 4

In Centriole, each triplet fibril consists of three microtubules or sub-fibres designated from inside to outside as A, B and C. The three microtubules are joined in such that A sub-fiber is a complete microtubule having 13 protofilaments while B & C sub-fibers are incomplete and share 2-3 protofilaments with A sub-fiber.

Microtubules are filamentous intracellular structures that are responsible for various kinds of movements in all eukaryotic cells. Microtubules are involved in nucleic and cell division, organization of intracellular structure, and intracellular transport, as well as ciliary and flagellar motility.

Pattern of organisation of cilia and flagella is 9 + 2 i.e. 9 in periphery and 2 in centre.

Electron transport system in mitochondria is located in inner membrane. 
Where it serves as the site of oxidative phosphorylation through the use of ATP synthase.

Sphaerosomes are small membrane bound organelles which take part in storage and synthesis of fats. They contain granular contents, rich in lipids but also have some proteins.

The enzyme urate oxidase or uricase catalyzes the oxidation of uric acid to 5-hydroxyisourate. Urate oxidase is mainly localized in the liver, where it forms a large electron-dense paracrystalline core in many peroxisomes.

• Vacuoles are the membrane-bound space found in the cytoplasm. It contains water, sap, excretory products and other material not useful for the cell.
• Vacuoles are bounded by a single, semipermeable membrane called tonoplast.
• This membrane facilitates the transport of a number of ions and other materials against concentration gradients into the vacuole.
• Thus, their concentration is significantly higher in the vacuoles than in the cytoplasm.

50 S subunit of ribosome is composed of 23S rRNA and a 5S rRNA + 32 different proteins.