Lecture 2

Question 1

List the 3 premises of the Cell Theory.

Answer 1

1. All living organisms are composed of cells
2. The cell is the basic unit of structure and organization in organisms
3. All cells come from pre-existing cells

Question 2

List the premise of the Reticular Theory of the nervous system.

Answer 2

1. The nervous system is made up of a single contiguous network

Question 3

What is the chemical name of the Golgi stain?

Answer 3

Potassium dichromate and silver nitrate

Question 4

What does the Golgi stain do?

Answer 4

Randomly labels a subset of neurons

Question 5

List the 3 premises of the Neuron Doctrine

Answer 5

1. Neurons are the functional units of the nervous system
2. Law of dynamic polarization (information travels from dendrites to axons)
3. Neurons communicate via regions of cell-cell contact

Question 6

List 3 issues with the Neuron Doctrine

Answer 6

1. Extensive gap junctions in the CNS encroach upon the reticular theory
2. Axons can act as dendrites, dendrites can act as axons (reciprocal synapses)
3. Signals can travel against “polarity” (e.g. back-propagating action potentials)

Question 7

Describe the mechanism of fluorescent dyes

Answer 7

Electrons of dyes absorb light and emit fluorescence as they drop back down to lower energy orbitals

Question 8

Define anterograde transport

Answer 8

Dye injected into soma

Question 9

Define retrograde transport

Answer 9

Dye applied to cut nerves

Question 10

Define dye coupling

Answer 10

Dye travels through gap junctions

Question 11

Define MitoTracker

Answer 11

Fluorescent dye labelling mitochondria

Question 12

Define LysoTracker

Answer 12

Fluorescent dye labelling lysosomes

Question 13

Define Phallacidin

Answer 13

Fluorescent dye labelling F-action

Question 14

What is the role of antibodies in fluorescent labelling?

Answer 14

Labelling specific proteins

Question 15

Define in situ hybridization

Answer 15

Detection of mRNA in tissues using antisense RNA (probe) + fluorescent dye

Question 16

Define immuno-labelling

Answer 16

Detection of proteins in situ using antibodies (generated with epitopes) + fluorescent dye

Question 17

Define GFP

Answer 17

Fluorescent protein cloned from jellyfish

Question 18

Define XFP

Answer 18

Mutated GFP (and mRFP) proteins produced to emit different colors

Question 19

How are fluorescent proteins used?

Answer 19

1. Expressed in specific neurons using cell-specific promotors (to drive expression)
2. Fusion proteins

Question 20

Define GCaMP

Answer 20

GFP protein that fluoresces in presence of Ca2+ (i.e. used to detect Ca2+ influx)

Question 21

Define Brainbow

Answer 21

“Technicolor” Golgi stain

Question 22

How does the Cre-Lox system work?

Answer 22

Cre recombinase snips DNA at Lox sites and rejoins.

Question 23

What do Lox sites pointing toward one another allow?

Answer 23

DNA inversions via combinatorial expression (Cre-Lox system)

Question 24

How many colors can be created by Brainbow?

Answer 24

10

Question 25

Define Serial EM reconstruction

Answer 25

Serial sections (slices) made from nervous system tissue, images with scanning electron microscopy, 3D image reconstructed using computer algorithms

Question 26

Define electrophysiology

Answer 26

The study of bioelectricity

Question 27

Define resting membrane potential

Answer 27

Difference in ion concentration across membrane at rest

Question 28

List 2 types of electrical signalling in excitable cells

Answer 28

1. Local graded potentials | 2. Action potentials

Question 29

Define local graded potentials

Answer 29

Currents leak out of membrane as they travel, or are consumed by membrane capacitance

Question 30

Define action potentials

Answer 30

Arise when local graded potentials activate voltage-gated ion channels

Question 31

What is the main function of action potentials in neurons?

Answer 31

Drive pre-synaptic secretion

Question 32

What is the main function of action potentials in muscles?

Answer 32

Drive muscle contraction

Question 33

What is the main function of action potentials in endocrine cells?

Answer 33

Drive secretion

Question 34

Where do (local graded and action) potentials travel?

Answer 34

Chemical pre-synaptic terminals

Question 35

Define ionotropic receptors

Answer 35

Translate neurotransmitter signals into electrical signals

Question 36

Define metabotropic receptors

Answer 36

Translast neurotransmitter signals into biochemical signals

Question 37

Define coupling coefficient

Answer 37

Quantify degree of current transfer possible between two cells

Question 38

Define connexins

Answer 38

Make up vertebrate gap junctions (connexons) and hemi-channels

Question 39

Define pannexins

Answer 39

Make up vertebrate hemi-channels

Question 40

Define inexins

Answer 40

Make up invertebrate gap junctions (innexons) and hemi-channels