Adaptations of Unicellular Organisms

1.2.3: Explain how various structures of unicellular organism help that organism

survive.

Essential Question: How do adaptations in unicellular

organisms enable them to survive in their environments?

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Contractile Vacuole• Vacuoles store materials

such as water, salts, proteins, and carbohydrates.

• In unicellular organisms like paramecium, they contain a vacuole called a contractile vacuole.– By contracting rhythmically,

this specialized vacuole pumps excess water out of the cell.

– This allows the cell to maintain homeostasis or balance.

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Cilia• Ciliates, like the paramecium,

use hairlike projections called cilia for feeding and movment.

• Cilia propel them through the water.

• They also line the organism’s gullet and move its food to the organisms interior.– The food particles are engulfed,

forming food vacuoles.– The contractile vacuoles collect &

remove excess water, which helps to achieve homeostasis.

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Flagella• Some prokaryotic cells use

flagella to propel themselves.• Flagella are whiplike

structures that are used for movement.

• Some eukaryotic cells have flagella as well.– Sponges carry out basic

functions, such as feeding and circulation, by moving water through their bodies.

– Choanocytes use flagella to move water through pores in the wall of the sponge and out through the osculum.

– As water moves through the sponge, food particles are filtered from the water, and wastes are removed from the sponge.

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Pseudopods• Some eukaryotic organisms move

by temporary cytoplasmic projections called pseudopods.

• Pseudopods are used for feeding and movement.

• An ameoba is a type of organism that uses pseudopods.

• These can also be called “false feet.”– The amoeba moves by first

extending a pseudopod away from its body.

– The cytoplasm then streams into the pseudopod.

– This is a slow but effective way to move from place to place.

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Eyespots• Plantlike protists, like

algae, possess a structure called an eyespot.

• This is used to help the algae find sunlight to power the process of photosynthesis.

• Flatworms have an eyespot that can detect changes in the amount of light in their environment.

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