concept 6.4: the endomembrane system, regulated proteins traffic and performs metabolic functions

what does the endomembrane system consist of

nuclear envelope, Endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, plasma membrane

describe the endoplasmic reticulum (ER)

accounts for more than half of the total membrane in cells, continuous with the nuclear envelope, made of two regions

smooth ER

lacks ribosomes, synthesizes lips and oils and steroids, detoxifies, metabolizes carbs

rough ER

studded with ribosomes, has ribosomes that produce and secrete proteins, distributes transport vesicles, membrane factory for the cell

describe the golgi apparatus

has distinct polarity and a cis and trans face, made of flattened membranous sacs called cisternae

cis face of G.A.

closer to the ER, accepts vesicles from the ER

trans face of G.A.

shipping side located away from the ER

functions of the golgi apparatus

modified products from the ER, makes non cellulose polysaccharides, sorts and packages materials into transport vesicles destined for plasma membrane or organelles

what are the two models for how substances move from cis to trans face in the golgi apparatus

vesicular transport model: macromolecules are transferred by vesicles, cisternal maturation model: cisternae of gogli progress from cis to trans face

what is the current consensus on how the golgi functions

central cisterna are non moving and outer cisternae are dynamic and able to move (a combination of the two models

describe lysosomes

a membranous sac of hydrolytis enxymes that can digest macromolecules

vacuoles

large vesicles that are derived from the ER and golgi apparatus

what are the three different types of vacuoles

food vacuoles, conractile vacuoles, central vacuoles

food vacuoles

formed by phagocytosis

contractile vacuoles

found in freshwater protists, pump excess water out of cells

central vacuole

found in plant cells, hold organic compounds and water, very important for plant cells and holding inorganic ions