PARAMECIUM
PARAMECIUM is a microscopic (very small), unicellular (one cell) protozoa (animal-like protist).
· It is plentiful in freshwater ponds.
Major Parts of a Paramecium
· Nucleus: “control center” (3)
· Pellicle: Thick membrane that gives the paramecium its shape (2)
· Cytoplasm: jelly-like substance that hold all the organelles (12)
· Cilia: hair-like projections that help it move (1)
· Contractile vacuole: Remove excess water
out of the cell; works like a pump. (5)
· Oral groove: takes in food (6)
· Food vacuole: digests food (8)
· Anal pore: Removes waste (9)
· Trichocyst: Protection or defense against predators (10)
Paramecium Movement
• The outer surface of the cell is covered with many hundreds of tiny hair-like structures called cilia.
• Act like “microscopic oars”
• Can swim backwards, forwards, or rotate using the cilia.
• Moves so quickly that we have to add a thickening agent or quieting solution to the slide to slow it down to study it.
Paramecium Feeding
• Feeding mechanism = oral groove (#6) and a funnel-shaped gullet (#7) into which food is drawn by the combined action of cilia which cover the body and other cilia lining the oral groove and the gullet. (Refer to picture)
• As it moves through the water it rotates on its axis and small particles of debris and food are collected and swept into the gullet.
• They feed on small organisms such as bacteria, yeasts, algae and even other smaller protozoa.
Paramecium Reproduction – Binary Fission
• Cell divides in two by a process called binary fission (asexual reproduction).
• 2 new cells are formed by splitting the original (cell then grows in size and makes structures).
• 2-3 times per day if conditions were right.
Paramecium Reproduction – Conjugation
• Can also reproduce sexually called conjugation.
• 2 cells coming together to exchange nuclear material.
• The two cells then separate and continue to reproduce by simple division.
• It is similar in some ways to sexual reproduction in more complex animals.
Paramecium Excretion
• Food waste left in a food vacuole is excreted through the anal pore (the vacuole and pore fuse.
• Other wastes left over from cellular activity (metabolic waste) simply diffuse through the pellicle.
• Excess water and some metabolic wastes are excreted through the contractile vacuole.