Question

Name the largest and the smallest cell.

Answer 1

Hint: The smallest cell lacks cell walls and is resistant to antibiotics whereas the largest cell is highly rich in protein and is used for human consumption.

Complete answer:
Mycoplasma or Pleuropneumonia-like organisms (PPLO) are the simplest and the smallest living cells. Their size ranges from 150-250 nanometer (nm) and they are non-motile.

- Mycoplasma is unicellular and prokaryotic and their outer covering constitutes of the plasma membrane as they lack a cell wall.
- Their cytoplasm does not have membrane-bound organelles and their genetic material is naked in the form of a single DNA duplex.
- They have a 70s ribosome and their mode of nutrition is heterotrophic, that is, they can either be saprophytic (drawing nourishment from dead organic matter) or parasitic (drawing nourishment from host organism).
- They lead to certain types of diseases in plants and animals. In plants, they cause diseases like witch’s broom (It changes the natural structure of the tree leading to the formation of thickened stems, discolored and distorted leaf, etc.) and in animals, they cause diseases like pleuropneumonia (It leads to inflammation of lungs in cattle and sheep).

The unfertilized egg cell of an Ostrich is the largest.
- Ostrich’s egg is 15 cm long and weighs around 1.4 kilograms(kg).
- An Ostrich lays an egg in a dump nest which contains more than 50 eggs at a time and the eggs require a period of 42 to 46 days to hatch.
- Ostrich’s egg has a high protein content and moderate fat content and due to this, it is often used for human consumption.

Additional information:
Mycoplasma were discovered in the pleural field of cattle suffering from pleuropneumonia and are gram-negative.
As they lack a cell wall, they are pleomorphic, that is, they can alter their structure and biological functions depending upon the environmental conditions.
Moreover, their lack of cell walls makes them resistant to antibiotics like penicillin and enzymes like lysozymes.

Note: Remember that the question is about the largest and the smallest cell present in nature and not about the largest and the smallest cell found in the human body.