endomembrane system quick flashcards

what does the endomembrane system consist of

plasma membrane

nuclear envelope

endoplasmic reticulum

golgi apparatus

lysosomes

vacuoles

what is the function of the endomembrane system

storage and trafficking - proteins and lipids

metabolism - biosynthesis of lipids/degradation of lipids/protein modification

detoxification

what does gated transport involve

transport via protein channels or pores

eg nuclear import/export

what does transmembrane transport involve

transport via protein translocation channels

eg protein entry into the ER

what does vesicular transport involve

transport via membrane-bound intermediates

eg transport from ER to Golgi

what is the endoplasmic reticulum

ER membrane - continuous with outer nuclear membrane

ER lumen - continuous with nuclear intermembrane space

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what does the smooth ER do

steroids hormone synthesis in gonad & adrenal cortex endocrine cells

calcium storage (important for muscle contractions and vesicle fusion)

detoxification (liver enzymes eg cytochrome p450 enzymes, break down drugs/toxins)

membrane lipid synthesis (with aid of phospholipid translocators like flippases)

what does the rough ER do

protein synthesis (ribosomes produce proteins for secretion or membranes)

protein translocation

protein glycosylation (attachment of carbs, important for quality control)

folding and quality control

protein translocation types

transmembrane proteins - inserted into ER membranes

water-soluble proteins - fully transported into ER lumen

what is a signal peptide

a “tag” on proteins for the endomembrane system

interacts with a cytosolic molecule (signal recognition particle)

what is the signal recognition particle

directs the ER signal sequence to a translocator

hydrophobic segments in transmembrane proteins are recognized like signal sequences

what is the transitional ER

exit site for proteins moving from ER to golgi

produces vesicles coated with COPII (transport protein)

in mutual feedback with golgi apparatus

what is the structure of the golgi apparatus

consists of flattened membranous sacs (cisternae)

cis face recieves vesicles from ER

trans face sends modified proteins/lipids to their final destinations

what does the golgi apparatus do

recieves proteins from ER and modifies them by: proteolysis, amino acid modification, modifying their carbohydrate chains

sorts and ships materials into transport vesicles

what do transport vesicles carry

transport vesicles bud off from one compartment and fuse with another, they carry to the target compartment material as:

cargo from the lumen

membrane of the donor compartment