cells alive 4- vesicular transport

what are the functions of the endoplasmic reticulum?

protein biosynthesis

lipid biosynthesis

intracellular Ca²⁺ store

what is the structure of the endoplasmic reticulum?

made up of tubules and sacs surrounded by membranes

the tubules and sacs are developed from the nuclear outer membrane and protrude into the cytoplasm

the space enclosed by the membranes is the lumen or the ER cysternal space

what are some post-translational modifications of the ER?

disulphide bonds which stabilise the protein

N-glycosylation which stabilise and protect from degradation

what are the protein modifications?

formation of disulphide bonds

proper folding

addition and processing of carbohydrates

specific proteolytic cleavages

assembly into multimeric proteins

what is the structure of the golgi apparatus?

it is located near the nucleus and close to the centrosome

it is divided into cisternae

what are the functions of the golgi apparatus?

carbohydrate synthesis

post-translational modifications of proteins and lipids

sorting and dispatching station for products of ER

what is an early endosome?

residue under plasma membrane

they mature into late endosomes

what is a late endosome?

a sorting compartment in the endocytic pathway

they are located near the nucleus

they are an acidic environment

what are the functions of lysosomes?

recycling

protection

how are vesicles formed?

cargo molecule binds to a transmembrane receptor

the curved coat protein is recruited and distorts the membrane

the vesicle is released by dynamin

the vesicle is rapidly uncoated

what is vesicle tageting?

vesicle surface markers identify the origin and the cargo

complementary receptors are displayed on target membranes

what is the transport between the ER and the golgi?

cargo is recruited to exit sites in the ER via a receptor is the cargo is soluble

COPII is recruited to cause budding

the vesicles then rapidly shed their coat

vesicles undergo homotypic fusion mediated by SNAREs

newly formed vesicular tubular clusters move along microtubules by dyneins

what is the golgi-ER retrieval mechanism?

the cargo is released, mediated by a decrease in pH

various proteins need retrieving

vesicles coated in COPI bud from VTC and golgi, uncoated and transported back to ER

the retrieval pathway can be hijacked by bacterial toxins to gain entry to the cytoplasm

what are the 2 pathways for exocytosis?

constitutive sensory pathway

regulated secretory pathway

what is endocytosis?

the intake of molecules from the extracellular space and from the membrane

what is pinocytosis?

the recycling of membrane and non-specific uptake

what is the process of phagocytosis?

the interaction of a receptor is the phagocytosis trigger

there is rearrangements of the cytoskeleton and pseodopods form

phagosomes are formed

the phagosome fuses with a lysosome

what can happen to endocytosed vesicles?

recycled

transcytosis

degradation