Transport Flashcards
test 1 content
which molecular motor class exists on microfilaments and what do they do?
myosins, a type of end motor that moves away from the MOC, slowest of the fast transport, have anterograde axoplasmic transfer (from cell body to axon), carry organelles, receptors, enzymes, and synaptic vesicles, carry resources to areas of active polymerization/growth
which molecular motor classes exist on microtubules?
kinesins and dyneins
what do kinesins do?
fastest transport, end motors move away from MOC, have anterograde axoplasmic transport towards axon terminal, carry secretory/transport vesicles, mitochondria, nucleus (for cell migration), mRNA actin, P enzymes, and myelin in oligodendrocytes to the end of a growing myelin sheath
what do dyneins do?
slower than kinesins, end motors move toward MOC, have retrograde exoplasmic transport towards negative end/cell body, carry endosomes, regulatory factors (factors that provide feedback about what is happening in terminals)
what are the slow transport motors and what do they carry?
slow transport entails rapid movement with pauses (1-2mm/day), kinesins and dyneins are the motors, neurofilaments are moved on microtubules further down axon, microtubules are moved on microfilaments because they cannot align since they are polar so they need to be moved, polypeptides, actin, and tubulin are also transported
what are some characteristics of dendrites?
cytosol is continuous with the soma, organelle density decreases toward tip/spines, rough ER is mostly in cell bodies, smooth ER can reach into spines, microtubules at base, microfilaments in the head
what are the two types of protein transport in dendrites?
canonical pathway: membrane proteins arrive on transport vesicles (AMPAR, GABAA)
local pathway: proteins are transported/modified in (NMDAR) or translated (actin) on smooth ER and sent to spine apparatus/golgi outpost for final post-translational modification, packaging and regulated release
what are some characteristics of axons?
past the axon hillock there are no resident organelles except for mitochondria and smooth ER, microtubules, neurofilaments, and microfilament rings, cargo
what organelles are on the axon/presynaptic terminal?
smooth ER make phospholipids that form local membrane and translate ribosomal, mitochondrial, and synthetic enzyme proteins from mRNA
what cytoskeletal elements are on the axon/presynaptic terminal?
microtubules (don’t enter axon terminal), neurofilaments, and mostly microfilaments
what types of vesicles are on the axon/presynaptic terminal?
transport (precursors, enzymes, reuptake proteins, endosomes), dense core (neuropeptides), and synaptic vesicles (neurotransmitters)
