Lecture 2 Flashcards
List the 3 premises of the Cell Theory.
- All living organisms are composed of cells
- The cell is the basic unit of structure and organization in organisms
- All cells come from pre-existing cells
List the premise of the Reticular Theory of the nervous system.
- The nervous system is made up of a single contiguous network
What is the chemical name of the Golgi stain?
Potassium dichromate and silver nitrate
What does the Golgi stain do?
Randomly labels a subset of neurons
List the 3 premises of the Neuron Doctrine
- Neurons are the functional units of the nervous system
- Law of dynamic polarization (information travels from dendrites to axons)
- Neurons communicate via regions of cell-cell contact
List 3 issues with the Neuron Doctrine
- Extensive gap junctions in the CNS encroach upon the reticular theory
- Axons can act as dendrites, dendrites can act as axons (reciprocal synapses)
- Signals can travel against “polarity” (e.g. back-propagating action potentials)
Describe the mechanism of fluorescent dyes
Electrons of dyes absorb light and emit fluorescence as they drop back down to lower energy orbitals
Define anterograde transport
Dye injected into soma
Define retrograde transport
Dye applied to cut nerves
Define dye coupling
Dye travels through gap junctions
Define MitoTracker
Fluorescent dye labelling mitochondria
Define LysoTracker
Fluorescent dye labelling lysosomes
Define Phallacidin
Fluorescent dye labelling F-action
What is the role of antibodies in fluorescent labelling?
Labelling specific proteins
Define in situ hybridization
Detection of mRNA in tissues using antisense RNA (probe) + fluorescent dye
Define immuno-labelling
Detection of proteins in situ using antibodies (generated with epitopes) + fluorescent dye
Define GFP
Fluorescent protein cloned from jellyfish
Define XFP
Mutated GFP (and mRFP) proteins produced to emit different colors
How are fluorescent proteins used?
- Expressed in specific neurons using cell-specific promotors (to drive expression)
- Fusion proteins
Define GCaMP
GFP protein that fluoresces in presence of Ca2+ (i.e. used to detect Ca2+ influx)
Define Brainbow
“Technicolor” Golgi stain
How does the Cre-Lox system work?
Cre recombinase snips DNA at Lox sites and rejoins.
What do Lox sites pointing toward one another allow?
DNA inversions via combinatorial expression (Cre-Lox system)
How many colors can be created by Brainbow?
10
Define Serial EM reconstruction
Serial sections (slices) made from nervous system tissue, images with scanning electron microscopy, 3D image reconstructed using computer algorithms
Define electrophysiology
The study of bioelectricity
Define resting membrane potential
Difference in ion concentration across membrane at rest
List 2 types of electrical signalling in excitable cells
- Local graded potentials
2. Action potentials
Define local graded potentials
Currents leak out of membrane as they travel, or are consumed by membrane capacitance
Define action potentials
Arise when local graded potentials activate voltage-gated ion channels
What is the main function of action potentials in neurons?
Drive pre-synaptic secretion
What is the main function of action potentials in muscles?
Drive muscle contraction
What is the main function of action potentials in endocrine cells?
Drive secretion
Where do (local graded and action) potentials travel?
Chemical pre-synaptic terminals
Define ionotropic receptors
Translate neurotransmitter signals into electrical signals
Define metabotropic receptors
Translast neurotransmitter signals into biochemical signals
Define coupling coefficient
Quantify degree of current transfer possible between two cells
Define connexins
Make up vertebrate gap junctions (connexons) and hemi-channels
Define pannexins
Make up vertebrate hemi-channels
Define inexins
Make up invertebrate gap junctions (innexons) and hemi-channels
