1. LOCOMOTION IN
PROTOZOA
Dr. Shampa Jain
Professor
Department of Zoology & Biotechnology Govt. M.H. College
of Home Science & Science for Women, Autonomous,
Jabalpur, M.P. India
2. TYPES OF LOCOMOTION IN PROTOZOA
Amoeboid locomotion
Flagellar locomotion
Ciliary locomotion
7. MECHANISM OF AMOEBOID MOVEMENT:
• Sol-gel theory or Change of viscosity theory:
• This theory was proposed by Hyman (1917) and strongly supported by Pantin (1923-26), Mast
(1925-31) and others.
•
This theory assumes that the pseudopodium is formed by the change of sol to gel and gel to
sol states in the peripheral cytoplasm. The tip of the pseudopodium controls the change.
• During the formation of the pseudopodium the plasma membrane of Amoeba gets attached
to the substratum by means of an adhesive secretion. A local reversion of plasmagel to
plasmasol takes place at the anterior end by internal chemical reaction.
• The gel at the anterior end becomes thinner and weak. The rest of the plasmagel exerts
pressure on the weakened area. The contracting plasmagel of the posterior end is continuously
changed into plasmasol and it flows forwards and breaks the weak gel.
8. MECHANISM OF AMOEBOID
MOVEMENT: SOL GEL THEORY CONT..
• Anteriorly the plasmagel tube is
continuously regenerated by gelation of
plasmasol and a new pseudopodium is
formed. The animal then progresses
forward with the help of the
pseudopodium.
• Remark:
Though the theory is most popular to the
zoologists but the actual mechanism of
reversion of gel to sol or vice versa could not
be explained properly
9. • Molecular folding and unfolding theory
• Goldacre and Lorch (1950) and Goldacre (1952) suggested that the protein molecules
in Amoeba are present in folded and unfolded forms and explained the molecular
basis of gelation (gel) and solation (sol) state of protoplasm of Amoeba. They
suggested that the force which is generated by the contraction of the plasma tube,
could not bring the locomotion of Amoeba alone.
• The forces which are generated by the folding and unfolding of the protein
molecules, could help in locomotion. The sol state of the protoplasm is due to the
folding of protein molecules and the gel state is due to the unfolding of protein
molecules.
• The folding of protein molecules occurs at the rear end of the ectoplasm in Amoeba
where the plasmagel converts into plasmasol which flows in front and by gelation it
forms pseudopod.
MECHANISM OF AMOEBOID MOVEMENT
CONT..
10. MECHANISM OF
AMOEBOID MOVEMENT :
MOLECULAR FOLDING AND
UNFOLDING THEORY CONT..• The gelation takes place by the
unfolding of the protein mol-
ecules within the tip of the
advancing pseudopod where
plasmasol is converted into more
rigid plasmagel (Fig. 10.61).
• Barrington (1967) has supported
this theory stating that the
required amount of energy
during pseudopodia formation
comes from adenosine
triphosphate (ATP).
11. MECHANISM OF
AMOEBOID MOVEMENT
• Fountain zone contraction theory
• This theory was proposed by Allen in 1962. According to him the endoplasmic molecules
start moving first at the anterior end before doing the same in the posterior end. So
according to him the locomotion of Amoeba is not effected by the squeezing from
behind- forwards. According to this theory, the endoplasm contains long, protein chains.
• These chains contract at the anterior end and at this end the plasmasol changes into
plasmagel by folding the protein chains. This plasmagel flows forward and touches the
hyalin cap and again flows backward creating a fountain-like appearance.
• This anterior region now develops a tension which is transmitted at the posterior end of
the endoplasm. It is due to fountain-like movement of the gel, Amoeba is forced forward.
The attachment of Amoeba to the substratum is necessary for locomotion.
16. METHODS OF FLAGELLAR
MOVEMENT
• Simple conical gyration or screw propeller theory :
• It postulates a spiral turning of the flagellum like a screw resulting a propeller action
which pulls the animal forward.
•
17. METHODS OF FLAGELLAR MOVEMENT
CONT..
• Paddlestroke movement theory: This theory is propsed by Ulehla and
Krijsman
According to this theory the ordinary
movement of a flagellum is a
sidewise lash consisting of an
effective downward stroke
followed by a relaxed recovery
stroke by which the flagellum
is brought forward again.
• Effective stroke
• Recovery stroke
Effective stroke
Recovery stroke
18. CILIA
• Definition : “Cilia are fine, short, hair-like, centriole-based protoplasmic
processes, characteristic of many protozoan and metazoan cells”.
• The cilia and flagella possess nearly the same structures except they
differ in some points
• Cilia are relatively shorter in length than the flagella.
• Comparatively cilia are more numerous in number than the flagella. The
cilia occur in patches or tracts but flagella generally occur singly or in
pairs.
• Absence of mastigonemes in cilia but present in flagella.
19. CILIA
• The microtubules of the axoneme extend from the base to the tip in
flagellum but in cilium the microtubules are reduced in number towards
the tip.
• Presence of kinetodesma in cilia but absent in flagella.
• The movement of the flagella and cilia exhibit certain differences.
Flagella exhibit undulating motion and beat independently but cilia in
the longitudinal rows beat perpendicularly one after another
(metachronous) and those in the transverse rows beat synchronously
21. MOVEMENT OF CILIA
• Effective stroke
• Ciliary Stroke
A ciliary beat cycle consists of
an effective stroke in which the
extended cilium makes an oar-
like movement towards one
side, and a recovery stroke in
which the cilium moves back by
propagating a bend from base
to tip.
