Lecture 1: Neuronal organelles and their function Flashcards
How many synapses are there? (if we look at the count of 86 billions neurons)
1 * 10^15 synapses (the synapse can carry out tasks and decisions without the need of the soma as this is too far from it)
Which challenges do neurons face?
1.How to get to the right place in the brain
2.With whom to make contact
3.How to generate and maintain polarization
4. How to supply distant synapses with proteins & lipids
5. How to maintain energy levels in distant synapses
6. How to respond to changes in local environment and activity
Earlier was thought all neurogenesis was in embryogenesis, why is this not true?
In the hippocampus, in later stages of life there is still neurogenesis.
How do synaptic versicles travel?
After filling with transmitters, synaptic vesicles are moved to the active zone of the presynaptic plasma membrane by a translocation process that may be either diffusion-limited or dependent on molecular motors.
Synaptic vesicles from from an axon and should not go into dendrites but into the axon. These vesicles fuse at the presynaptic terminal at the position of the active zone.
What does synapse function require?
Energy, proteins and lipids.
What happens in priming and docking
Vesicles are primed, or docked, with a large supramolecular complex around a core assembled SNARE complex, awaiting calcium influx to trigger fusion.
Why are the postsynaptic density darker coloured?
Because all the receptors are located there.
What for function are microdomains characterized with?
These microdomains play a crucial role in organizing signaling events in polarized cells like neurons, essential for neuronal processes such as differentiation, synapse formation, and neurotransmission.
What happens in the axon initial segment?
In this place, AP are generated but it also acts as a barrier for proteins that have to go into the dendrite and not go in the axon.It thus makes sure nerons are polarized and stay polarized.
What does the neuromuscular junction have or is characterized with?
NJ has a lot of organelles and mitochondria.
How many active zones does Neuromuscular Junction have?
This synapse has two active zones. In your brain synapses, you have often only one active zone while in the NJ, there are two which is important because of their high-release probability, more versicles can fuse and be released for a longer time.
The synapses in the hippocampus, with only ….
one active zone
What is the Zip-code?
These sequences of neucleotides, or what scientists refer to as RNA “Zip-codes” are recognized by proteins that act like mail carriers and deliver RNAs to where they are supposed to go.
What is the SER generally used for?
The creation/storage of lipids and steroids
What is the function of the RER?
RER plays a significant role in the synthesis of various proteins.
What are the posttranslational modifications in the golgi?
Glycosylation and sorting for transport
What are the major organelles required for neuron and synapse function?
The mRNA leaves the nuclear envelope and is then translated and migrates into the ER.
Transmembrane proteins are formed in the ER and leave in vesicles via the ER exit sites. They
then pass the ER Golgi intermediate complex (ERGIC) and then go into the Golgi. In the Golgi,
the proteins mature a bit more but they are still immature and are glycosylated with
posttranslational modification. Then they will enter the TGN where they are sorted
(constitutive release; …). On their way to the plasma membrane, they will mature: and will
contain the proteins needed to fuse with the membrane (SNARE). This was believed until 10
years ago.
What is the organization of Cellular Secretory Organelle: ER
- continuous network in soma, dendrites & axon
- Present in pre- & postsynaptic terminals
- Allows local protein translation → They think that one synapse will become very active,
however, they do have a low lifetime (they do not go to the Golgi) - Major calcium store
- Major lipid source (one big lipid bilayer
