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Biochem Final Study Guide
Terms in this set (77)
Describe the structure and function of a typical neuron.
The shape of a typical neuron is specialized for communicating with other cells. Lots of dendrites. Axon endings on other side of neuron.
What does an axon do?
send message over distances
What does the nucleus do?
directs everything in the neuron
What does the myelin sheath do?
What does the Node of Ranvier do?
lets the message jump from place to place
What does cell body do?
Holds the nucleus
Explain what is meant by saying that the plasma membrane is "selectively permeable". Evaluate How/Why the characteristic of selective permeability is essential to the function of the plasma membrane.
some molecules go through, others wont. Membrane proteins will transport hydrophilic molecules to enter the cell.
Explain what is meant by describing the plasma membrane as a fluid mosaic.
"movable" pieces (protein)
Evaluate How/Why the organization as a fluid mosaic is essential to the function of the plasma membrane
-attachment to the cytoskeleton and ECM
Explain why phospholipids can spontaneously assemble into a lipid bilayer
-hydrophobic stick together
-hydrophilic stick together
Define and explain the phenomenon of diffusion.
Movement of molecules of any substances that they spread out evenly into the available space.
Describe three characteristics of a molecule that determine whether it can or cannot diffuse through the plasma membrane.
List two specific examples of molecules that can and cannot diffuse through the plasma membrane.
-water (need aqua porons)
-ions (need pump)
Define and explain the phenomenon of osmosis
diffusion of free water across a selectively permeable membrane, whether artificial or cellular
Define and explain hypertonic
concentration of water molecules is higher in the solution outside the cell than inside (cell is shriveled)
Define and explain hypotonic
concentration of water molecules is lower in the solution outside the cell than inside (cell is bigger - hypo hippo)
Define and explain isotonic
concentration of water molecules is the same in the solution outside the cell as it is in the inside (cell is same size throughout)
What is simple diffusion?
passes through membrane without aid
What is active transport?
pump a solute across a membrane against its gradient requires work (energy)
Compare and contrast simple diffusion and active transport.
-no energy required (concentration gradient)
-direction of solute (high to low)
-energy required (ATP)
-direction of solute (high; against gradient)
What are 2 examples of active transport?
K+ and Na+
What are 2 examples of simple diffusion?
Oxygen and CO2
Explain how the sodium potassium pump employs active transport to create concentration gradients and a charge gradient across the plasma membrane of a neuron.
1. (3) Na+ ions come in from the cytoplasm and binds to the pump
2. phosphate group attaches in the cytoplasm from the mitochondria and breaks off a phosphate ATP -> ADP
3. the sodium-phosphate pump flips over from the energy given by the phosphate and releases the Na+ ions into the extra-cellular fluid
4. the (2) K+ ions come from the extracellular fluid and attach to the pump and the phosphate breaks off
5. the phosphate breaking off caused the pump to flip back over facing the cytoplasm
6. the (2) K+ions are released from the pump into the cytoplasm; the concentration gradient is then:
Na+ high, K+ low, in the extracellular fluid
Na+ low, K+ high, in the cytoplasm
occurs in active transport
Using (axon, Ca 2+, ligand-gated ion channels, neurotransmitter, presynaptic cell, postsynaptic cell, presynaptic membrane, postsynaptic membrane, synaptic cleft, synaptic vesicle, voltage-gated Ca 2+ channel) describe the structure and function of a neuronal synapse.
1. an action potential arrives, depolarizing the presynaptic membrane
2. depolarization opens voltage-gated channels triggering an influx of Ca 2+
3. elevated Ca 2+ concentration causes synaptic vesicles to fuse with the presynaptic membrane, releasing neurotransmitters into the synaptic cleft
4. neurotransmitter binds to ligand-gated ion channels in the post-synaptic membrane (binding triggers opening allowing Na+ and K+ to diffuse through)
Explain how a neurotransmitter communicates across a synapse and then is recycled. Explain why a given neurotransmitter will affect some neurons but not others
-if it elicits an action potential
-excitatory vs. inhibitory
-ligand-gated ion channel just may not exist to bind neurotransmitter (affect some neurons)
-if Cl is there it wont; its negative so it will take it away from threshold
Compare and contrast the electrical signal of the action potential within a neuron and the chemical signal of neurotransmitters between neurons. Alike? Different?
-Electrical: moves down ONE neuron
-Chemical: for communication between neurons
-both carry a message
Describe the role of the sodium potassium pump in the generation of an electrical signal with a neuron versus the chemical signals between neurons.
Resting membrane potential (-70)
Describe the role of the voltage gated sodium (Na+) channel in the generation of an electrical signal with a neuron versus the chemical signals between neurons.
generate action potential (+30)
Describe the role of the voltage gated potassium (K+) channel in the generation of an electrical signal with a neuron versus the chemical signals between neurons.
-generate action potential (+30)
Describe the role of the voltage gated calcium (Ca 2+) channel in the generation of an electrical signal with a neuron versus the chemical signals between neurons.
-part of chemical
-triggers vesicles to fuse with presynaptic cell
Describe the role of the ligand dependent ion channel in the generation of an electrical signal with a neuron versus the chemical signals between neurons.
-part of chemical
-what the neurotransmitter binds to in the next cell
What unit is current measured in?
What unit is resistance measured in?
What unit is power measured in?
What unit is voltage measured in?
What is the function of a battery in a circuit?
power supply (voltage)
What is the function of a resistor in a circuit?
What is the function of a load in a circuit?
-turns electrons into a useable form of energy
What is the function of current in a circuit?
flow of electrons
Compare and contrast what is meant by the terms "closed circuit" vs. "open circuit".
-continuous flow of electrons
-light bulb on
-not continuous flow of electrons
-light bulb off
Mathematical formula that shows the relationship between voltage, current, and resistance.
battery=amount of electrons x whats pushing back
volts=amps x ohms
Mathematical formula that shows the relationship between power, current, and voltage.
light bulb=how much electricity going through x battery
watts=amps x volts
What happens to a circuit when the wire is made longer?
What happens to a circuit when the wire is made shorter?
What happens to a circuit when the wire is made wider?
What happens to a circuit when the wire is made narrower?
What is the resistance of a device if the current is 10 amps and the voltage across is 5 volts.
If a device is plugged into a 110-V power source and has a resistance of 100 ohms, what is the current through it?
How much power is used when a 3V battery produces 0.1 amp of a current?
How much power is used by a 9-V battery that produces a 3 amp current?
What power is used if a resistance of 100 ohms has a current of 0.1 amps flowing through it?
What is the power used in a device if the resistance is 100 ohms and the voltage across it is 4V?
What is a poison? How do we know if a particular chemical is a poison? (Use toxicity, dose, exposure, response, bioassay)
-poison kills you (its a drug that does this)
-LD50 is based on dose and route of exposure (dermal, oral, and inhalation)
-LD50 is a measure of how toxic it is to kill you
-bioassay is an assessment on living things
Explain how the LD50 of a toxic chemical is determined and what it means.
LD50 is the dose it takes to kill 50% of the population
What does a low LD50 tell you?
have a low dose to kill you (more harmful)
What does a high LD50 tell you?
have a high dose to kill you (less harmful)
By what means can one be exposed to a toxic chemical?
Why does the route of exposure matter?
it may be toxic one way and not the other
What does oral exposure mean?
through the mouth
What does dermal exposure mean?
through the skin
What does inhalation mean?
breathing it in
Which value is least toxic?
the highest # for mg/kg
Which value is the most toxic?
the lowest # for mg/kg
Who is more likely to be harmed and why with exposure to a toxic chemical?
-The person around it
-The person with the biggest body weight / amount of exposure
example : 90 lb baby to 10 g of C02 would be 9
vs. 180 lb man to 10 g of C02 would be 18 (9 is more toxic)
What does ED50 tell you?
what is successful in working in 50% of the popualtion
What does the TD50 tell you?
when it is toxic for 50% of the population
What does the LD50 tell you?
when it kills 50% of the population
Compare and contrast ED50, TD50, LD50.
-good for you
-when it is bad for you and can kill you
-when it will kill you
Which value is usually the lowest? ED50, TD50, LD50.
Which value is usually the highest? ED50, TD50, LD50.
How is therapeutic index measured?
What does the therapeutic index (TI) mean?
is a comparison of the amount of a therapeutic agent that causes the TE to the amount that causes death / toxicity
What is a toxic effect?
what it takes to be toxic
What does a low IT mean?
small distance between being toxic vs. therapeutic
What does a high IT mean?
big distance between being toxic vs. therapeuitc
Where might pollutants be found? How does the location of a pollutant impact its relative risk?
-air (#1 contact)
-human created and exposed
-how it affects you (route of exposure)
What factors must be considered when evaluating the relative risk of exposure to a given pollutant?
-route of exposure
-has different effects
-human health risk
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