Amoeba

An amoeba is a unicellular, shapeless, and colorless microorganism composed of a jelly-like structure capable of continually changing shape due to its flexible cell membrane and cytoplasm.​

Structure and Organelles

The main parts are the plasma membrane, cytoplasm (differentiated into outer ectoplasm and inner endoplasm), and a centrally located nucleus that controls all functions and contains genetic material.​

Amoeba possess pseudopodia (“false feet”), which are finger-like cytoplasmic extensions used for movement and engulfing food particles by phagocytosis.​

Other organelles include food vacuoles (where ingested food is stored and digested), contractile vacuoles (regulate water balance/osmoregulation), mitochondria, Golgi apparatus, and fat globules.​

Function and Adaptation

Amoeba moves by extending and retracting its pseudopodia, allowing rapid changes in shape and locomotion—this is termed “amoeboid movement”.​

It feeds using phagocytosis (engulfing solid food) and pinocytosis (absorbing liquids), digesting particles inside food vacuoles.​

Reproduction is asexual, typically by binary fission, producing identical daughter cells; under harsh conditions, amoeba form protective cysts and 'reawaken' when conditions improve.​

Although its lifespan is just a few days, binary fission essentially makes the lineage immortal.