leaving certificate biology
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Amoeba
Leaving Certificate Biology
H. Jones, St. Columbas College
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Amoeba
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Characteristics of ProtistaContains single-celled and simple multi-cellular organisms
They are eukaryotic they have a membrane-enclosednucleus and membrane enclosed organelles
Some feed by taking in organic substances, others can
photosynthesise.Include:Amoeba moves by means of pseudopods and is well known
as a representative unicellular organism.Algae a large and diverse group of plant like organisms
ranging from unicellular to multicellular formsParamecium consist of a single cell yet are visible to thenaked eye
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AmoebaConsists of a single cell
It is a consumer. It feeds on small plants, animals and bacteria
It lives in freshwater ponds (most likely to be found on themud at the bottom)
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CytoplasmEctoplasm
Endoplasm
Nucleus
Pseudopod
Contractile Vacuole
Food Vacuole
Fat Droplets
Waste products
Structure of AmoebaCell membrane
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Endoplasm andEctoplasm
The endoplasm is fluid-like. It has a grainyappearance due to thepresence of food
vacuoles and wastematerials
Ectoplasm can becomesoft in places to allowthe development of
pseudopodia
EndoplasmEctoplasm
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Development ofPseudopod
Pseudopods arereferred to as falsefeet as they areproduced at any point
on the body and haveno fixed position
Pseudopodia extend inthe direction Amoebawishes to move
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Development ofPseudopod
Pseudopods developwhen the ectoplasmsoftens and moves
forward and theendoplasm moves into replace it
Amoeba uses
pseudopodia toengulf its prey
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Endoplasm and
ectoplasm
Before After
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Food vacuoles Amoeba feeds by
surrounding its preywith pseudopodia andsecreting digestiveenzymes into thevacuole created
Food can then be
stored within thevacuole.
Food vacuole
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Food vacuoles
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The Contractile Vacuole
High
sugar/saltconcentration
Low sugar/salt
concentration
Amoebas
cytoplasm is moreconcentrated than
the surrounding
fresh water
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As a result water
constantly rushes in
by osmosis
The Contractile Vacuole
High
sugar/saltconcentration
Low sugar/salt
concentration
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In order to deal with
this uptake of waterAmoeba forms a
contractile vacuole
Excess waterenters the
contractile vacuole
The Contractile Vacuole
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The contractile
vacuole swells with
water and moves to
the edge of thecell
The Contractile Vacuole
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The contractile
vacuole swells with
water and moves to
the edge of thecell
The Contractile Vacuole
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The contractile
vacuole swells with
water and moves to
the edge of thecell
The Contractile Vacuole
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Where it bursts
and expels the
water
The Contractile Vacuole
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Where it bursts
and expels the
water
The Contractile Vacuole
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Where it bursts
and expels the
water
The Contractile Vacuole
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Where it bursts
and expels the
water
The Contractile Vacuole
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The cycle is thenrepeated
The Contractile Vacuole
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Contractile vacuoleThe contractile vacuole is said to be
responsible for osmoregulation
Without it the Amoeba would expand and
burst
Contractile vacuole
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Contractile vacuolebursting
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