Neurites Flashcards
test 1 content
what is the function of the cytoskelton?
determines neuronal morphology and polarity, contributes to structural plasticity and neuronal excitability since polymerization can build up spines which makes the cell more easily excitable, involved in trafficking of organelles, neuropeptides, precursors and refuse
what are the three components of the cytoskeleton?
microtubules (largest diameter, longest, 25nm), neurofilament (10 nm), and microfilaments (smallest diameter, <10 nm)
what are microtubules made of?
helical structure of alpha tubulin-beta dimer protofilaments that are stabilized by GDP-monomer cap, tau and MAP3 in axons and MAP2 in dendrites that help clip the rings together so that they don’t separate
how do microtubules grow?
positive ends of microtubules extend out of microtubule organizing centers where the negative end is attached, proximal dendrites have mixed orientations, distal dendrites have mostly positive ends out, axons have mostly positive ends out, polymerization/depolymerization on positive end contributes to structural plasticity
what diseases are associated with microtubule breakdown?
microtubule breakdown leads to tau protein accumulation, tau can then collect into neurofibrillary tangles causing alzheimers and parkinsons disease
what are neurofilaments made of and what do they do?
structural support found only in neurons (mostly in axons) that maintain axonal shape and diameter, made of coiled-coil tetrameric structure of neurofilament proteins (neurofilament light/medium/heavy molecular proteins, internexin, and peripherin), these protein tails permit regular spacing between the filaments
what diseases are associated with mutations in the genes that encode neurofilament proteins?
NF-L: charcot marie tooth syndrome, parkinsons and ALS
NF-M: ALS, parkinsons and alzheimers disease
NF-H: ALS and alzheimers disease
what makes up microfilaments and where are they located?
actin double helix structure makes up microfilaments and they are border to plasmalemma on axons and spines, actin rings support neurite branch points and stabilize location of axonal ion channels
what is the function of microfilaments?
contain a growth cone for axonal developments and form a scaffolding that isolate incompatible synapses from one another, can undergo activity-dependent actin polymerization to create spines or depolymerization to remove them
how do microfilaments support spine growth?
Arp2/3 supports branch points, capping proteins stabilize (attach when its time to stop growing), and cofilin and profilin regulate branching and polymerization, spine maturation increases strength of the synaptic contact, branching microfilaments are in the head and microtubules are in the neck
what are the 4 steps of spine maturation?
filopodia (non-functional) -> thin spine (non-functional) -> stubby spine (can start attaching to pre-synaptic neuron) -> mushroom spine (fully functional)
