18 public questions tagged with this topic.
Cilia are usually shorter and more numerous than flagella, which are longer and fewer in number. This follows from NCERT principle where relation explains outcome clearly for students.
Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Biology - Botany portion covering relevant concept, Topic: Plant structure, physiology and applications.
Basal bodies serve as dedicated microtubule-organizing centers for ciliary and flagellar assembly, derived from centrioles through maturation and membrane docking. Each barrel consists of nine triplet microtubules with distal and subdistal appendages that anchor to the plasma membrane and recruit intraflagellar transport proteins. They template the nine doublet microtubules of the axoneme via transition zone proteins that establish ciliary gate function, ensuring selective entry of tubulin and dynein arms. Unlike the pericentriolar centrosome that nucleates interphase radial arrays and mitotic
Ref: Alberts et al., Molecular Biology of the Cell, 6th ed., Ch 17; basal body templates cilia/flagella as MTOC.
Axonemal architecture highly conserved across eukaryotes from unicellular Chlamydomonas algae to human respiratory epithelium reflecting efficient solution for producing bending from linear motor sliding requiring precise geometry. Transmission electron micrograph cross section shows nine microtubule doublets arranged in ring each doublet complete A tubule 13 protofilaments plus partial B tubule 10 protofilaments equally spaced 30 nm apart around circumference. In motile flagella two central single microtubules C1 C2 encircled by inner sheath and connected to outer doublets via radial spokes T
Ref: Mitchell, 2004; Alberts et al., Molecular Biology of the Cell – 9+2 microtubule arrangement canonical in eukaryotic cilia.
Cilia and flagella motility requires active sliding filament machine within conserved axoneme evolutionary ancient. Structure nine outer doublet microtubules surrounding central pair retains dynein motors as exclusive driver of beating: outer dynein arms contain two or three heavy chains per arm inner arms more heterogeneous but also axonemal dynein isoforms both anchored to A tubule via docking complex and reaching to B tubule of neighboring doublet executing ATP hydrolysis cycle. Power stroke toward minus end attempts to slide doublets relative each other but nexin dynein regulatory complex
Ref: King, J Cell Sci 2012 – Dynein motor protein moves cilia and flagella beating machinery.
Motile cilia and flagella beating powered exclusively by axonemal dynein distinct isoforms from cytoplasmic dynein-1 adapted for high duty cycle sliding. Outer and inner dynein arms attached every 24 and 96 nm along A tubule heavy chains contain AAA ring and microtubule binding stalk pointing toward adjacent B tubule executing ATP hydrolysis cycle. Cycle drives linker bending delivering power stroke causing interdoublet sliding about 5 microns per second in disintegrated axoneme. In intact cilia doublets anchored at basal body and crosslinked by nexin dynein regulatory complex forces converted
Ref: Viswanadha et al., Biosci Rep 2017 – Dynein powers ciliary and flagellar movement via axonemal arms.
Cilia are comparatively short and work like oars, moving either the cell or the surrounding fluid. Flagella are longer and are mainly responsible for movement of the cell.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Cytoskeleton Cilia Flagella Centrosome Nucleus and Chromosomes
The axoneme usually contains nine radially arranged peripheral microtubule doublets and a pair of centrally located microtubules. This organisation is called the 9+2 array.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Cytoskeleton Cilia Flagella Centrosome Nucleus and Chromosomes
The organism is a euglenoid. Euglenoids possess a flexible pellicle and two unequal flagella. They photosynthesise in sunlight but behave as heterotrophs by preying on smaller organisms when sunlight is unavailable.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Five Kingdom Classification and Kingdom Plantae Animalia
Euglenoids possess two flagella of unequal lengthâone short and one long. They also have a flexible, protein-rich pellicle instead of a cell wall.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Fungi - Deuteromycetes and Economic Importance
Trypanosoma is a flagellated protozoan. Members of this group may be free-living or parasitic and possess flagella; parasitic forms can cause diseases such as sleeping sickness.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Euglenoids Slime Moulds Protozoans
Dinoflagellates possess one longitudinal and one transverse flagellum. Euglenoids also possess two flagella, but these are described as one short and one long.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Euglenoids Slime Moulds Protozoans
Trypanosoma is a parasitic flagellated protozoan that causes sleeping sickness. Plasmodium belongs to the sporozoans, while Paramoecium is a ciliated protozoan.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Euglenoids Slime Moulds Protozoans
