Plant Cell Types Hand-out PDF

BIO 14 (Biodiversity) Lecture Hand-out Summary of Cell Types in Plants CELL TYPE CHARACTERISTICS LOCATION FUNCTION Parenchyma Shape: commonly polyhedral (many- Throughout t...

BIO 14 (Biodiversity) Lecture Hand-out Summary of Cell Types in Plants CELL TYPE CHARACTERISTICS LOCATION FUNCTION Parenchyma Shape: commonly polyhedral (many- Throughout the plant, as Metabolic processes like sided); variable parenchyma tissue in cortex, respiration, digestion, and as pith and pith rays, or in photosynthesis; storage and Cell wall: primary, or primary and xylem and phloem conduction; wound healing secondary; may be lignified, suberized, and regeneration or cutinized Living at maturity Collenchyma Shape: elongated On the periphery(beneath the Support in primary plant body epidermis)in young Cell wall: unevenly thickened; primary elongating stems; often as a only- nonlignified cylinder of tissue or only in patches; in ribs along veins in Living at maturity some leaves Fibers Shape: generally very long Sometimes in cortex of Support stems, most often associated Cell wall: primary and thick secondary- with xylem and phloem; in often lignified leaves of monocotyledons Often (not always) dead at maturity Sclereids Shape: variable; generally shorter than Throughout the plant Mechanical ; protective fibers Cell wall: primary and thick secondary- generally lignified May be living or dead at maturity Tracheid Shape: elongated and tapering Xylem Chief water-conducting Cell wall: primary and secondary; element in gymnosperms and lignified;contains pits,but not seedless vascular plants; also perforations found in angiosperms Dead at maturity Vessel member Shape: elongated, generally not as long Xylem Chief water-conducting as tracheids element in angiosperms Cell wall: primary and secondary; lignified; contains pits and perforations; several vessel members end-to-end constitute a vessel Dead at maturity Sieve cell Shape: elongated, and tapering Phloem Chief food-conducting element in gymnosperms and Cell wall: primary in most species; with seedless vascular plants sieve areas; callose often associated with wall and pores  Living at maturity; either lacks or contains remnants of a nucleus at maturity; lacks distinction between vacuole and cytoplasm Albuminous cell Shape: generally elongated Phloem Believed to play a role in the movement of food into and Cell wall: primary out of the sieve cell Living at maturity; associated with sieve cell, but generally not derived from same mother cell as sieve cell; has numerous connections with sieve cell Sieve-tube member Shape: elongated Phloem Chief food-conducting element in angiosperms Cell wall: primary , with sieve areas; sieve areas on end wall with much larger pores than those on side walls- this wall part is termed a sieve plate; callose often associated with wall and pores Living at maturity; either lacks a nucleus at maturity, or contains only remnants of nucleus; contains a proteinaceous substance known as slime, or P-protein in dicots and some monocots; several sieve-tube members in a vertical series constitute a sieve tube Companion cell Shape: variable, generally elongated Phloem Believed to play a role in the Cell wall: primary movement of food into and Living at maturity; closely associated out of the sieve-tube member with sieve-tube members; derived from same mother cell as sieve –tube member; has numerous connections with sieve-tube member