Question

Define Binary fission in Leishmania.

Answer 1

Hint: Binary fission is the process in which an organism duplicates its genetic material and divides into two organisms receiving one copy of DNA each. It is type of asexual reproduction.

Complete answer:
Binary fission is a type of asexual reproduction. A unicellular organism such as bacteria and protozoa simply splits into two equal halves during cell division. In amoeba, splitting of the two cells during division can take place in any plane. Plasmodium, the malarial parasite divides into many daughter cells simultaneously by multiple fissions. Some unicellular organisms (Leishmania) show more organization in their bodies and it is a part of Euglena. Leishmania have a whip-like structure (flagellum) at one end of the cell and binary fission occurs in a definite orientation in relation to this structure.
Binary fission can occur in four ways:
Irregular: In this fission can take place in any plane like amoeba.
Longitudinal: The fission takes place along the longitudinal axis. e.g. Euglena.
Transverse: The fission takes place along the transverse axis. e.g. paramecium.
Oblique: The fission takes place obliquely. e.g. Ceratium.
In Leishmania, binary fission occurs in a definite orientation:
Nuclear division is followed by the appearance of a constriction in the cell membrane.
The membrane grows transversely inwards from the middle of the dividing cell.
Cytoplasm separates into two equal parts having one nucleus each.
The daughter cell may separate from each other and forms two new organisms.

Note: This form of sexual reproduction and cell division is also used by some organelles like mitochondria. Leishmania is responsible for a disease called Kala-azar. Kala-azar also known as Leishmaniasis. In this disease, parasites migrate to internal organs such as the liver, spleen and bone marrow. Symptoms of this disease are fever, weight loss, fatigue and anemia.