Endomembrane System Flashcards
Endomembrane system
Nuclear envelop, endoplasmic reticulum, golgi apparatus, lysosomes, vesicles and vacuoles, plasmamembrane
the endomembrane system is connected
through direct physical continuity or by transfer of membrane segments as tine vesicles
The endoplasmic reticulum accounts for
half of the total membrane in many eukaryotic cells
Smooth Endoplasmic reticulum
outer surface lacks ribosomes
Smooth ER synthesizes
lipids (oils, steroids, new membrane phospholipids), metabolism of carbohydrates, detoxification of drugs and poisions (add hydroxl group making it more water soluble), and storage of calcium (in muscle cells)
Rough endoplasmic reticulum
studded with ribosomes on the outer surface of the membrane (folds are called cisternae, and space in between the ER called lumen)
Rough ER function
secretes glycoproteins, has transport vesicles transporting protein, membrane factory of the cell.
EX: pancreatic cells synthesize the protein insulin and secrete it into the bloodstream.
glycoproteins
proteins with carbohydrates covalently bonded to them
Transport vesicles
vesicles in transit from one part of the cell to another
Golgi apparatus
warehouse for receiving, sorting, shipping and even maufacturing (made of flatten disk called cisternae)
Products of the ER
such as proteins are modified and stored then sent to other destinations, all within the golgi apparatus
Cis face of golgi apparatus is
usually located near the ER (receiving), vesicles go to this side
Trans face of golgi apparatus gives
rise to vesicles that pinch off and travel to other sites (shipping)
products sent to the golgi apparatus are
modified during their transit from cis to trans face
Lysosomes
membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest (hydrolyze) macromolecules.
Digest fats, proteins, polysaccarides, and nucleic acids
hydrolytic enzymes and lysosomal membranes are made by
the Rough ER and then transported t the golgi apparatus for further processing
Phagocytosis
the process of ameobas and unicellular protist eating smaller organisms or food particles by engulfing them
food vacuoles fuse with
lysosomes, whose enzymes then digest the food
The digestion products, of the lysosomes
pass into the cytosol and become nutrients for the cells
Macrophages carry out
phagocytosis, white blood cells that help defend the body by engulfing and destroying bacteria and other invadors
Autophagy
lysosomes use their hydrolytic enzymes to recycle the cell’s own organic material
autophagy process
a damaged organelle becomes surrounded by a double membrane which the lysosome fuses with. The the lysosomal enzymes dismantle the inner membrane and the enclosed material, resulting in small organic compounds being released into the cytosol for reuse.
Vacuoles
large vesicles derived from the ER and Golgi
The vacuolar membrane is
selective in transporting solutes
food vacuoles are
formed by phagocytosis
Contractile vauoles
pump excess water out of the cell maintaining a suitable concentration of ions and molecules in the cell
central vacuole
found i mature plants, develops the coalescence of smaller vacuoles
the sap in the central vacuole contains
the cells main repository of inorganic ions like potassium and chloride
The central vacuole absorbs
water, enabling the cell to become larger, playing a major role in plant growth
The path of secretory protein follows from synthesis through secretion
Endoplasmic reticulum –> Cis golgi cisternae –> medial golgi cisternae –> trans golgi cisternae –> plasma membrane
