Cell Bio Test 2: Techniques, Membrane Potentials, and Nerve Impulses

What is SDS-PAGE?

SDS-Polyacrylamide Gel Electrophoresis is a process that sorts proteins based of size. SDS is a detergent that denatures proteins by creating covalent bonds and completely unfolds the protein. Bigger, heavier proteins travel less far on gel plate than smaller, lighter proteins.

What is Western blot?

The Western Blot technique is used to confirm the presence of a specific protein. SDS-PAGE is done first to separate out proteins with similar weights. Antibodies are used because they exclusively bind to one protein and depending on which antibodies bind, we can determine which protein is present.

What is the analysis of enzyme kinetics?

Michaelis-Menten equation shows the relation between substrate concentration and velocity of enzyme reactions by measuring rate of product formation (velocity of reaction). Each enzyme has a set amount reactions that it can catalyze in a given amount of time, this is what determines the velocity of reaction because the enzyme can only move so fast (there is no want to overload it or make it go faster). The Vmax is reached as the substrate concentration increases

What is Fluorescence Microscopy

Green fluorescent protein (GFP) comes from jellyfish and is used to stain molecules to make them glow under UV light. GFP changes shape when hit with the right color of light. It absorbs UV light and emits a green color instead.

What is Fluorescence Recovery After Photobleaching (FRAP)?

FRAP is used to determine the mobility of proteins in a cell. Fluorescent microscopy is used. Integral membrane components are stained with fluorescent dye. Photobleach a certain spot with a laser beam by directing so much light to a specific area so the GFP no longer emits its green light. How long the area that photobleaching take to recover (if at all) can tell scientists if the proteins were moving or if they weren’t affected by

What is a membrane potential?

The difference in voltage/energy on one side of the cell membrane compared to the other side.

What is resting potential?

The membrane potential when a nerve or muscle cell is in an unexcited state.

What types of cells have resting potential?

Only muscle or nerve cell (though all cells have membrane potential)

What is a neuron?

a nerve cell

What are the parts and their function of a neuron?

Dendrites — fine, branched extensions that extend from the cell body. Receives incoming info usually from other neurons.

Cell body — central part of the neuron that has the nucleus.

Axon — one prominent extension from the cell body which conducts outgoing impulses. Impulses move toward the terminal knobs. Axons can be microscopic in length or extend inches to meters.

Myelin sheath — covers axons to protect them

Terminal knob — at the very end of the neuron where impulses are transmitted from neuron to target cell

How are K+ gradients maintained?

the sodium-potassium pump

What ions are concentrated inside the cell?

K+

What ions are concentrated outside the cell?

Na+, Cl-, and Ca+

How is an action potential generated?

by stimulating the neuron which creates a change in membrane potential; transmits information

What are the stages of an action potential?

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depolarization, repolarization, hyperpolarization

what is “all-or-nothing” behavior?

Neurons will either fire a full action potential (impulses that transmit info) or nothing at all.

What does the speed of a neuron depend on?

• axon diameter (larger diameter = faster)

• how myelinated the axon is (more myelinated = faster)

Describe the propagation of an impulse for a non-myelinated and myelinated neuron???***

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Non-myelinated neurons don’t move signals down the axon, so they can’t relay information??

Myelinated neurons can move impulses down axon to relay information??

What is a synapse?

where neurons “connect” (they don’t actually touch but there is a microscopic gap)

Why are neurotransmitters important?

they transport information from a neuron to another cell (either a neuron or something else)

How is neurotransmitter action terminated?

reuptake — proteins assist with moving neurotransmitter back to the presynaptic cleft (the neuron where the neurotransmitters originally came from)

enzymatic degradation — enzymes destroy the neurotransmitters in the synaptic cleft (the microscopic gap between the terminal knobs and another cell)

What is impulse transmission (with acetylcholine as neutrotransmitter)

Electrical impulses are moved across the synaptic gap with the help of neurotransmitters. As a specific example, acetylcholine is released by terminal knobs of the vagus nerve.

How do different cone snail toxins affect impulse transmission?

A cone snail is a venomous snail that injects 4 types of toxins (conotoxins) inhibit impulse transmission to muscle cells. They use this to paralyze their prey, but it can also harm humans. that

Two of the toxins plug the receptors on the postsynaptic cell (muscle cell), one of the toxins plugs the channels on the presynaptic cell that release neurotransmitters (nerve), and the 4th toxin plugs all the sodium channels (which help with the impulse process)