Molecular Bio & Modifiable Synapses Flashcards
Ionotropic vs Metabotropic receptors
(Also called ligand-gates ion channels)
Neurotransmitter activates channel, which opens pore thru membrane
- 5 receptor subunits
Neurotransmitter activates receptor, which activated G protein
- Either opens G-protein gated ion channel or activated effector enzyme
- Can:
1) convert extracellular signals into the change of molecules inside neuron
2) amplify signals
3) regulate cell functions in response to signals
Glutamate receptor
Voltage-gated ion channels
Binding of glutamate opens AMPA, kainate, or NMDA
- AMPA and Kainate allows Na+ in
- NMDA allows Ca2+ in and also relies on voltage
Opens/closes in response to membrane potentials
- Glutamate will activate it but still needs membrane potential to open it completely
Signaling cascade
First messenger
Second messenger
Process found w/ metabotropic receptors
First messenger - Usually neurotransmitter or hormone
Second messenger - Molecule that relays signal from receptor to target molecules inside cell
- Usually calcium or cAMP
cAMP dependent pathway
1) First messenger binds to receptor
- Usually acetylcholine, dopamine, serotonin
2) G protein activates and activates adenylate cyclase w/ GTP
3) Adenylate cyclase uses ATP to create cAMP as signal molecule
4) cAMP activates protein kinase A to phosphorylate proteins or initiate protein synthesis
How many phosphates in:
ATP/GTP
ADP/GDP
AMP/GMP
3
2
1
(more phosphate ions = more energy)
Where do these take place?
Transcription from DNA to RNA w/ mRNA
Translation of RNA into proteins w/ Transfer RNA
Nucleus
Ribosomes at endoplasmic reticulum
Nitrogenous bases in DNA?
Uracil in RNA is paired with what?
Adenosine - Thymine
Guanine - Cytosine
Adenosine
_ nucleotide -> _ codon -> _ amino acid
3
1
1
How many essential amino acids are there?
Structure?
20 amino acids
Contains amino group, hudrogenC carboxyl, and R-group
- R-group is hydrophobic or hydrophilic -> Determines where on cell protein will be
Membrane potential
Difference in electrical charge between the inside and outside of a cell
- Resting membrane potential = ~-70 mV
Distribution of ions inside/outside of cell:
Sodium
Potassium
Chlorine
Calcium
Protein
Na+: More outside
K+: More inside
Cl-: More outside
Ca2+: Much more outside
Proteins: More inside
Equilibrium potential
Na+, K+, Cl-, Ca2+
Value of membrane potential where electrical force = diffusion force of ion
Potassium channel allows K+ ions to move from inside to outside of cell
- Driven by concentration gradient
-> Buildup of positive charge outside causes K+ to move back in driven by electrical gradient
Na+: 56 mV (Diffusion force in, electric force in (later out))
K+: -102 mV (Diff force out, electric force in)
Cl-: -76 mV (Diff force in, electric force out)
Ca2+: 125 mV (Diff force in, electric force in (later out))
- Much higher than Na+ bcuz diff of conc between inside and outside is much greater
EPSPs vs IPSPs
Axon hillock
EPSPs: Excitatory postsynaptic potential
- Depolarization of cell membrane
IPSPs: Inhibitory postsynaptic potential
- Hyperpolarization of membrane potential
Axon hillock: Where axon comes out of cell body
- Contains many voltage-gated sodium and potassium ion channels
- Where summation of EPSPs and IPSPs happen
Speed of voltage-gated sodium channels and voltage-gated potassium channels during action potentials
V-gated Na+ channels open first
- Rapidly activate and deactivate before V-gated K+ channels open
V-gated K+ channels open more slowly
Myelin sheath at peripheral nervous system vs central nervous system
Node of ranvier
Saltatory conduction
@ PNS - Schwann cell
@ CNS - Oligodendrocyte
Node of ranvier: Gaps between myelin sheath
- Depolarizes action potentials to increase speed
Saltatory conduction: Jumping of APs between nodes to travel as fast as 120 m/s
