Tag: single membrane bound organelles

Groups of dynein molecules responsible for movement in opposite directions are probably activated and inactivated in a coordinated fashion so that the cilia or flagella can move back and forth.

Pili, Fimbriae and flagella are structures that are found on the cell wall of the bacteria. These are structures that are made out of cellular components like proteins, for example, Pilli is made up of the protein pilin and flagella is made up of the protein flagellin.

• Cilia and flagella are small hair-like projections from the cell and are composed of microtubules which are arranged with their positive end at the outer tip of the axoneme.
  
• A microtubule is a tubular linear polymer of tubulin protein which is a part of the cytoskeleton that helps to provide structure and shape to the cytoplasm of a eukaryotic cell.
  
• So, the correct answer is 'Microtubules'.

The 9+2 arrangement of fibrils is characteristics of eukaryotes being comprised of 9 peripheral doublet and 2 central singlet fibrils. Although the 9 + 2 pattern is the fundamental pattern of virtually all cilia and flagella, the axonemes of certain sporozoan protozoans and some insect sperm show some interesting variations. The spermatozoids of flatworms are also atypical. The eel sperm shows 9+0 arrangement. These atypical cilia and flagella, which are all motile, show that the central pair of singlet microtubules is not necessary for axonemal beating and that fewer than nine outer doublets can sustain motility, but at a lower frequency.

Cilia are short, hair like appendages extending from the surface a living cell. Cilia are found exclusively in the prokaryotes.

Oxysomes are found in inner mitochondrial membrane and also called ad $F _1$ or elementary particles. It contains enzymes ATP synthase responsible for synthesis of ATP. They act as phosphorylating unit.

Spherosomes are membrane covered small spherical organelles which synthesize and store fats. They are covered with a single half unit membrane.

Endomembrane system of a eukaryotic cell is a membrane system that involves flow of membranes from one component to another by means of small membrane vesicles. The endomembrane system of a eukaryotic cell consists of endoplasmic reticulum, Golgi apparatus, lysosomes and plasma membrane.

Spherosomes are membrane covered small spherical organelles which synthesize and store fats. They develop from endoplasmic reticulum. In some plants, spherosomes have lysosomal activity, e.g., maize root tip.