chapter 4 matching 9

ECM

Layers of firm material scattered onto the primary cell walls inner surface that strengthen the wall and maintain its shape

tight junctions

Seal abbutting cells that lone the piter surfaces and internal cavities of animals so no fluids can pass between them

cuticle

a protective body covering made of cell secretions

middle lamella

a sticky layer in between the primary walls of adjoining cells

lignin

a strong waterproof component of the secondary wallsof older stems and roots

adhering junctions

anchor cells to each other and to the extracellular matrix

plasmadesmata

cytoplasmic channels that cross the cell walls and join neighboring plant cells

secondary wall

nonliving mixture of fibrous proteins and polysaccharides surrounding the cells that secrete it

gap junctions

open channels that connect the cytoplasm of neighboring animal cells

pectin

substance a young plant cell first secretes onto the outer surface of its plasma membrane

cellulose

the main constituent of a plants primary cell wall

primary wall

thin, pliable structure made of polysaccharides that allows plant cells to grow and enlarge