Cell: Unit of Life Test - 4

Mitochondria are present in both plant as well as animal cells. Plastids and central vacuoles are present in plant cells and centrioles are present in only animal cells.

All animal cell have two small organelles called centrioles. Each centriole is surrounded by dense amorphous protoplasmic masses called Massules.

Glycocalyx differs in composition and thickness among different bacteria. It could be a loose sheath called the slime layer in some, while in others it may be thick and tough called the capsule. The cell wall determines the shape of the cell and provides a strong structural support.

Cellular Totipotency is the ability of a single cell to produce all cell types and to organise them into an entire organism when cultured in a suitable culture medium at appropriate temperature and aeration conditions. Spores and Zygote are examples of totipotent cells.

The shapes of bacteria are bacillus (rod like), coccus (spherical), vibrio (comma shaped) and spirillum (spiral).

Animal cell do not possess plasmodesmata but it contain ribosomes, centriole andplamalemma. Plasmodesmata is the connection between two plant cells.

The first man to witness a live cell under a microscope was Anton van Leeuwenhoek, who in 1674 described the algae Spirogyra. Van Leeuwenhoek probably also saw bacteria.

All living organisms are composed of cells and products of cells.all cells arise from pre-existing cells.

Mitochondria contain cristae, finger like projection of inner layer, thylakoid is present in chloroplast and lysosome is a digestive enzyme but RNA is absent in Chromosome.

Fluid-Mosaic model is the most recent and accepted model of plasma membrane. This model was proposed by Singer and Nicolson in 1972. The quasi-fluid nature of lipid enables lateral movement of proteins with in the overall bilayer.

PPLO (Pleuro Pneumonia Like Organisms). They are generally smaller and multiply more rapidly than the eukaryotic cells.

Idiogram is a diagrammatic or systematized representation of the chromosome complement of an individual, species, or other group of organisms, indicating the number of chromosomes and their lengths, arm length ratio, centromere position, banding pattern.

A special membranous structure is the mesosome which is formed by the extensions of plasma membrane into the cell.

Cytoskeleton is a series of intercellular proteins that help a cell with shape, support andmovement. So, cytoskeleton is made up of proteinaceous filaments.

A bacterial flagellum has 3 basic parts: a filament, a hook, and a basal body.

1) The filament is the rigid, helical structure that extends from the cell surface.

2) The hook is a flexible coupling between the filament and the basal body.

3) The basal body consists of a rod and a series of rings that anchor the flagellum to the cell wall and the cytoplasmic membrane.