GERO 315g Study Guide - Spring 2018, Comprehensive Midterm Notes - Protein, Neuron, Wireless Access Point
GERO 315g
MIDTERM EXAM
STUDY GUIDE
Fall 2018
Inside the Neuron •
Membranes and Ions - construction of membrane and movement of molecules across it ◦
nerve cells communicate with electricity •
Vocabulary ‣
hydrophobic - water fearing •
hydrophilic - water loving •
active transport - requires energy, takes things from low to high concentration •
passive diffusion - usually gasses passing through the membrane •
facilitated diffusion uses proteins to help large molecules cross the membrane •
Cell membranes acts as a barrier to transport, allowing only certain substances to pass through it ‣
built with hydrophobic lipid tails (water fearing) → prevents large molecules like glucose and hydrophilic •
(water loving) substances, like sodium ions, from crossing the membrane
only thing that crosses easily is small molecules, like O2 and CO2 •
lower concentration of these molecules inside the cell, allows these small molecules to diffuse easily ◦
to move large hydrophilic molecules across the barrier, transport proteins are used to allow them to cross the •
membrane → they are specific to each type of hydrophilic moleucle
transport proteins use no energy, called facilitated diffusion ◦
can move substances either down or up a concentration gradient ‣
active transport → requires energy, moving from an area of lower concentration to higher concentration •
ex. keeps the concentration of a substance low inside a cell, but the cell must expend energy to do so ◦
Structure and function of a single neuron ◦
Dendrites receive signals ‣
as a neuron gets activated by incoming signals, goes to cell body → cell body integrates and makes decision •
on importance
if signal is important enough to the cell body/hillock discharges and signal goes out the axon to the ◦
next neuron
terminates at the synaptic terminal sends signal across synapse ◦
In the cell body we have the nucleus. Activity on the neuron will influence the nucleus to make proxies based •
on the needs of nerve cells (using DNA expression and RNA recipes)
more activity → bigger (grow the neuron connections) ◦
less activity → smaller ◦
Neurons come in many different shapes and sizes, the branched structures are called dendrites ‣
when signals come in from other neurons, the dendrites process them - the contact point = synapse •
cell body in the middle makes proteins and energy to run the cell •
the axon is long and has a constant diameter, usually only one in a neuron •
send electric signals called action potentials over long distances ◦
at the end of the axon, there are synaptic terminals → the synaptic terminals are almost touching the ◦
dendrites of other neurons
Nerve Cells as Batteries ◦
Different ions have different concentrations inside (intracellular) and outside (extracellular) Potassium diffusing ‣
out, negatively charged proteins pulling them back in; creates an equilibrium (resting membrane potential) where
there's not net change in K+ concentration, at 60mV
Diffusion → concentration gradient ‣
Electrical → negatively charged proteins ‣
POTASSIUM ALWAYS IS THE ONE THAT DETERMINES THE RESTING MEMBRANE POTENTIAL ‣
Neurons process info in the form of electrical signals (nerve impulses or action potentials) that travel along •
their axons (long extensions of the plasma membrane)
diffusion - random movement of particles until equilibrium •
Neurons are surrounded by a plasma membrane that is impermeable to ions → allows the neuron to maintain •
different concentrations of ions between the inside and the outside of the cell by preventing passive diffusion
typical neuron: large difference in concentration of ions between inter/extracellular environments (such as •
Na+ and K+) → interior of cell has a high concentration of protein ions, each w/ a neg. charge
only way ions can diffuse across the membrane is by passing thru specialized channels that permit the ◦
movement of particular ions while excluding others, can be in an open or closed state
neuron at rest → ion channels are CLOSED - however, K+ channels are open and they are free to diffuse •
very few Na+ ions are open when the neuron is at rest ◦
Battery Example: Net movement of electrons based on metal plates and acid environment ‣
Electrons in battery = ions of nerve cells •
Recharge by loading electrons with the alternator •
Alternator in battery = food and oxygen converted by mitochondria into ATP •
Constantly recharging •
How Substances Move Thru Cell Membranes ◦
find more resources at oneclass.com
find more resources at oneclass.com
cells regulate their water content thru osmosis - movement of H2O cells across the cell membrane ‣
aquaporins - transport proteins that move the water through the cell membrane •
hypertonic - high concentration ‣
hypotonic - low concentration ‣
uses the net movement of ions to dictate activity, when ion channels open to create a signal we lose the ability •
to repeat → need to recharge
ATP / Adenosine Tri-phosphate = the energy used in active transport ‣
ATP to help recharge the cell using the Na-K pump. ‣
To get more ATP we use cellular respiration, which uses sugar and oxygen. •
Resting and Action Potential ◦
Neutral Membrane - no charge ‣
Resting Membrane - -70mV inside vs. outside of membrane ‣
Hyperpolarized - more negative than -70mV inside ‣
hyper negativity inside the cell •
Threshold potential - -55mV ‣
Action Potential (peak) - +30mV inside ‣
establishing the resting potential has 2 phases: ‣
creation of concentration differences of specific ions inside and outside the cell by membrane bound pumps •
Na+,K+, -ATPase pump pumps 3 Na+ ions out of the cell and 2 K+ ions into the cell ◦
Potassium is responsible for resting potential because of the diffusion force and the electromotive force. - Imposing ‣
a charge on the nerve cell causes the voltage-gated Na channels to open, which lets in Na+.
This further pushes the charge higher positive and causes more Na+ channel to open -> action potential •
Larger but equally short pulse - AP stays the same ◦
Longer pulse - multiple APs ◦
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Membranes and ions - construction of membrane and movement of molecules across it nerve cells communicate with electricity. In the cell body we have the nucleus. Activity on the neuron will influence the nucleus to make proxies based on the needs of nerve cells (using dna expression and rna recipes) more activity bigger (grow the neuron connections) less activity smaller. Different ions have different concentrations inside (intracellular) and outside (extracellular) potassium diffusing out, negatively charged proteins pulling them back in; creates an equilibrium (resting membrane potential) where there"s not net change in k+ concentration, at 60mv. Potassium always is the one that determines the resting membrane potential. Neurons process info in the form of electrical signals (nerve impulses or action potentials) that travel along their axons (long extensions of the plasma membrane) diffusion - random movement of particles until equilibrium. Battery example: net movement of electrons based on metal plates and acid environment.
