BIO 203 Investigating Plant Cells, Tissues, and Primary Growth for Pre-Lab Quiz 3

Important characteristics of plant cells

-cell walls made of cellulose
-intercellular cytoplasmic connections
-generally 1 large central vacuole
-plastids
-no centrioles

middle lamella

clear streaks between adjacent primary cell walls

plasmodesmata

dark purple streaks

Characteristics of the primary cell wall

-extensible
-can undergo reversible changes in thickness
-cells that produce only primary cell walls have living protoplasts at maturits
-have plasmodesmata

Characteristics of the secondary cell wall

-stiff
-can not undergo reversible changes in thickness, no cellular expansion
-cells that produce secondary cell walls do not have living protoplasts at maturity
-no plasmodesmata

Characteristics of vacuoles

-comprise most of the living plant cell volume
-surrounded by tonoplast (membrane that regulates passage into and out of vacuole)
-provide hydrostatic support (turgor)
-store dissolved salts
-hold protons and regulate cytoplasm pH

Characteristics of plastids

-major plant organelles
-involved in photosynthesis and storage
-contain chloroplasts (chlorophyll) and chromoplasts (carotenoids)

Characteristics of meristematic tissue

-located at the tops of roots, stems, and branches
-insdie stems and roots of woody plants

Apical meristem

add cells to increase plants length/heights (primary growth)

Lateral meristem

add cells that increase girth of woody dicots (secondary growth)

Characteristics of dermal tissue

-basic epidermal cells (flattened with interlocking cell walls, lack chlorophyll and protection is their function)
-guard cells (surround the stoma and are able to change shape by taking on water by opening stops or losing water by closing stoma)
-trichomes (specialized hair-like epidermal cells that act as anti-predatory defense)
-root hairs (tubular extensions of individual epidermal cells near root tips that greatly increase surface area for water and mineral absorption

Characteristics of ground tissue: Parenchyma

-function in photosynthesis, storage, secretion (most common cells in primary plant body)
-retain protoplast at maturity
-large vacuoles
-thin primary cell walls
-can differentiate into other cell types

Characteristics of ground tissue: Collenchyma

-function in support via a hydrostatic mechanism
-retain protoplast at maturity
-primary cell walls of uneven thickness (appear thick at corners)
-elongate cell shape

Characteristics of ground tissue: Sclerenchyma

-fibers that protect plant phloem from incests
-sclereids found in layers in seed coats that provide embryonic protection

Characteristics of vascular tissue: Xylem

-principle water conduction tissue
-no protoplasts at maturity
-secondary cell walls
-tracheids (long, narrow, spindle shaped cells with tapered ends)
-vessel elements (large, barrel shaped cells joined end to end to form tubes. transport water more efficiently than tracheids and thought to have evolved from tracheids)

Characteristics of vascular tissue: Phloem

-principle food conducting tissue
-living protoplast at maturity
-sieve-tibe members (cylindrical cells with living protoplast, no nucleus, end walls that connect adjacent cells are called sieve plates perforated by plasmodesmata connections)
-companion cells (adjacent to sieve-tube members and connected by plasmodesmata. load and unload organic material used by sieve tube members)