ULTRASTRUCTURE OF FLAGELLATED PROTOZOA

ULTRASTRUCTURE OF FLAGELLATED PROTOZOA

·    The Flagellated protozoans range from a simple Oval cell with one or more flagella to the structural sophistication of the collared flagellates.

Pellicle

·       A thin, flexible membrane that supports the plasma membrane and helps them to change shape.

Plasma membrane

·   The selectively permeable membrane that protects the inner content of the cell from the outside environment.

Cytoplasm

·       A jelly-like substance distributed throughout the cell that contains all the cell organelles.

Chloroplast

·  Contains the green pigment chlorophyll that helps them to produce food using sunlight by Photosynthesis. 

Nucleus

·       A membrane-bound organelle that contains the Genetic material, DNA.

·       Nucleus also contains a distinct Nucleolus that contains RNA and helps the cell to synthesize Proteins.

Mitochondria

·       The energy-producing organelle that forms ATP.

·       All cellular activities such as movement and reproduction are performed using the mitochondrial energy source.

Ribosomes

·      Ribosomes (80S type with 60S and 40S sub-units) consists of RNA and proteins, and are responsible for the synthesis of cellular proteins.

Golgi apparatus

·       Manufactures, stores, and transports large molecules such as Carbohydrates and Proteins within the cell.

Endoplasmic Reticulum

·   Endoplasmic Reticulum is the extensive network of membranes that helps to package and transport proteins to different organelles.

·       Endoplasmic Reticulum is of two types:

i)      Rough Endoplasmic Reticulum (RER) – Containing Ribosomes attached to it.

ii)    Smooth Endoplasmic Reticulum (SER) – Devoid of Ribosomes.

Lysosomes

·      Small membrane-bound organelles filled with Hydrolytic enzymes that break down large molecules such as Carbohydrates, Fats and Proteins.

Contractile vacuole

·       Contractile vacuoles maintain the water and salt balance within the cell (Osmoregulation).

Reservoir

·       The inward pocket present near the base of the flagella where Contractile vacuole dispels excess water.

Flagella

·       Flagella is a long whip-like structure attached externally to the cell body that helps in cell movement.

·       Some Protozoa contain two Flagella,

i)      Short one that does not protrude out of the cell

ii)    Long one that helps in swimming

Eyespot

·      A region that is highly colored and contains red-colored Carotenoid pigments that help in the detection of light. It is sometimes called a Stigma.

Photoreceptor

·     Also known as the Paraflagellar body, it is the light-sensitive region located near the Flagellum that helps to detect light.

·       It also helps in their movement towards and away from light stimuli, a process known as Phototaxis.

Paramylon

·  Paramylon are stored starch-like carbohydrate granules composed of glucose produced during Photosynthesis.

·      Paramylon enables the organism to survive in low-light conditions when photosynthesis is not possible by acting as the food reserve for the cell.

·   When the paramylon is enclosed in a sheath of polysaccharide, it is called the Paramylon sheath of Pyrenoid.