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4-4: Unique Features of Plant Cells. Plant Cells. 3 Additional structures are found in plant cells: Cell Walls Central Vacuole Plastids Why? Different lifestyles compared to animal cells Go through photosynthesis CO 2 + H 2 O = sugars. Cell Wall.
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Plant Cells • 3 Additional structures are found in plant cells: • Cell Walls • Central Vacuole • Plastids • Why? • Different lifestyles compared to animal cells • Go through photosynthesis • CO2 + H2O = sugars
Cell Wall • Location: rigid covering outside C.M. (composed of cellulose – stored glucose) • Function: support + protection • Two types: • Primary – develops right outside C.M. • Secondary – develops between primary + C.M. but only when plant cell reaches full size; tough and woody structure • Ex. Your desk tops has billions
Vacuole • Location: within the cytosol • Size: may occupy up to 90% of the plant cell’s volume; formed by fusion of smaller vacuoles • Function: Fluid-filled vacuoles store enzymes + metabolic wastes, toxic materials, pigments
Plastids • Location: within the cytosol • Appearance: double-membraned organelle which contains DNA • Functions: • Storage of fats or starches • Storage of pigments • Most common type – chloroplast • System of thylakoids in stacks (grana) • Contain chlorophyll – pigment that captures light nrg • Site of photosynthesis • Endosymbiosis • Chloroplasts thought to be descendants of ancient prokaryotic cells that were incorporated into plant cells
Plastids • Chromoplasts • Contain colorful pigments • Ex. carotenoids • May/may not be involved in photosynthesis • Amyloplasts • Store starch • Precursor to plastids? • Protoplastids
Cell Comparison • Prokaryote vs. Eukaryote • Pro: lacks nucleus + membrane-bound organelles, genetic info. contained within nucleoid region • Plant vs. Animal • Plant: Cell Walls, Vacuole, Plastids