exam 3 Flashcards
1
Q
what directs the synthesis of proteins
A
genetic information
2
Q
T/F the cell expresses all genes at the same rate
A
FALSE: genes are expressed at different rates depending on what protein is being synthesized bc the body might need more/less of that protein
3
Q
what is the difference between DNA and RNA
A
DEOXYribonucleic acid vs RIBOnucleic acid mwans that the sugar in the backbone has on less oxygen in DNA, and RNA uses uracil instead of thymine
4
Q
what bonds hold the backbone of RNA together
A
phosphodiester bonds
5
Q
how many strands does DNA have
A
2
6
Q
how many strands does RNA have
A
1
7
Q
T/F RNA base pairs can pair to each other
A
TRUE: this often happens to help fold the RNA into a specific shape by connecting base pairs that are close together
8
Q
what is the difference between conventional and nonconventional base pairs
A
conventional: A-U; C-G
nonconventional: anything else that happens when RNA is folding to a shape, but there still happen to keep the shape together even though its not favorable
9
Q
what does the DNA coding strand do
A
the coding strand directly matches what the RNA is going to look like, but it does not work to guide the RNA synthesis
10
Q
what does the DNA template strand do
A
the template strand is what the RNA strand is based off of, and the complimentary pairs that form the RNA are taken from this strand
11
Q
what protein transcribes the DNA into RNA
A
RNA polymerase
12
Q
what direction is RNA synthesized in
A
5’ to 3’
13
Q
what direction is the template strand being read in
A
3’ to 5’
14
Q
T/F only one RNA polymerase can work at a time
A
FALSE: there can be many polymerases synthesized different parts of the gene at once
15
Q
what does messenger RNA (mRNA) do
A
codes for proteins
16
Q
what does ribosomal RNA (rRNA) do
A
forms the core of the ribosome’s structure and catalyzes protein synthesis
17
Q
what does transfer RNA (tRNA) do
A
serves as adaptors between mRNA and amino acids during protein synthesis
18
Q
what does the promoter on DNA do
A
it tells the RNA polymerase where to begin the gene transcription
19
Q
what does RNA polymerase do when it reaches the promoter
A
it begins transcription there and it releases it’s sigma factor which is what read the promoter gene
20
Q
what does the terminator on DNA do
A
it tells the RNA polymerase where to stop the transcription of the gene
21
Q
T/F only side of the DNA strand can be the template strand
A
false, both can be the template strand but for different genes and they can read multiple in opposite directions at once
22
Q
how many RNA polymerases are there
A
3
23
Q
what does RNA polymerase I do
A
it transcribes most rRNA genes
24
Q
what does RNA polymerase II do
A
it transcribes all protein genes
25
what does RNA polymerase III do
it transcribes tRNA and other small RNAs
26
what does RNA polymerase II need to start transcription
general transcription factors
27
what is the TATA box
the promoter that tells the polymerase where to begin transcription
28
how is the TATA box read
the general transcription factor TFIID is what moves along the DNA, and the TBP (tata binding protein) is what reads and recognizes the tata box
29
what happens after the TATA box is read
the TFIID binds to the DNA and distorts the shape of it, which allows the TFIIB and all the other general transcription factors to bind
30
what does the TFIIB do
this is what goes along the DNA strand and hold the TBP
31
what does the TBP do
this is the TATA binding protein that is on the TFIIB and reads the TATA sequence
32
what does the TFIIB do
this is the first general transcription factor that attaches to the kinked strand once the tata box is read
33
what does the TFIIH do
this opens the double helix DNA strands at the transcription start point by using ATP
this also phosphorylates the RNA polymerase II to start the transcription
34
generally, what does TFIIF do
helps the RNA polymerase II connect onto the other transcription factors before it starts transcription
35
generally what does the TFIIE do
this is part of the formation and activation of the RNA polymerase II
36
what is the location of the TATA box
-30
37
what general transcription factor binds at -35
TFIIB
38
what general transcription factor binds at -30
TBP which is within TFIID
39
how does RNA polymerase II transcribe the DNA that is wrapped around a histone (in a nucleosome formation)
elongation factors
40
where are eukaryotic mRNAs processed
in the nucleus
41
what 3 things can help modify an RNA as it is being transcribed
capping factors, splicing factors, polyadenylation factors
42
what are the special structures on mRNA
has a cap on the 5' end and a poly-A tail on the 3' end
there are also untranslated regions after the cap and before the poly-A tail, but have the actual coding sequence in between them. 5'UTR and 3'UTR
43
what does the capping factor do to the RNA
this makes it start to become mRNA bc it adds a cap to the 5' end of the RNA that is being created
44
what does the polyadenylation factor do to the RNA
this makes the poly-A tail on the 3' end of the mRNA
45
when are the cap and poly-A tail added
after transcription has finished
46
what is the structure of the 5' cap on mRNA
7-methylguanosine and a triphosphate bridge
47
what is an intron
a non coding gene in a eukaryotic DNA strand
48
what is an exon
a coding sequence of DNA in a eukaryotic cell
49
what turns the pre-mRNA into mRNA
the introns are removed by splicing factors to turn the pre mRNA into regular mRNA
- the untranslated regions stay at the ends
50
how does RNA splicing work
spliceosome takes the intron and makes it into a lariat (a lasso looking circle thing) and it then gets removed
- the mRNA gets put back together then
51
T/F splicing has to happen after synthesis
FALSE: these processes can be happening on the same strand at the same time, but the synthesis has to be complete before that specific area can be spliced
52
what happens to the intron lariats
they will eventually get degraded into the nucleus
53
what is an alternative splicing mean
when a pre-mRNA actually has an exon removed to form another type of mRNA
54
where do mRNAs have to go before they can be translated
they have to go from the nucleus where they were made and be exported to the cytosol through pores in the nuclear envelope
55
what does the poly-A binding protein and the cap binding protein do
this binds to the poly-A tail and the cap to tell the transport molecule that the mRNA is complete and can be exported through the nuclear envelope pores
56
T/F prokaryotes are easier to produce mRNA in than eukaryotes
TRUE: prokaryotic cells have transcription and translation occurring in the same location in the cell, so translation can happen before transcription even finishes
57
what happens to all mRNAs eventually
they degrade into RNases
58
what is the start codon for all proteins
M methionine - AUG
59
what is the central dogma
DNA to RNA to PROTEIN through replication transcription translation
60
how many reading frames are there
3
61
what is a frame shift mutation
where one or two bases is removed the protein doesn't form like normal bc the reading frame has been shifted to reflect something else
62
how did researchers decipher genetic code
they put different mRNAs into a translation system and saw the different types of polypeptides that were produced
63
what shape do tRNA molecules usually form into
a clover
64
what is the anticodon
at the bottom clover of the tRNA, there is a codon that base pairs with the amino acid that is attached at the top of the tRNA, so that it can look for that amino acid along the strand
65
what does the tRNA do
they are adaptors that link the amino acids to the codons
66
what enzyme couples the tRNA to the correct amino acid
aminoacyl-tRNA synthetase
67
what does the aminoacyl-tRNA synthetase do
it has a tRNA in it, and it finds the correct amino acid to attach to the top of it.
this will be used when the tRNA matches with it's opposite codon on the mRNA strand which then the amino acid at the top can be added to the protein chain
68
where is mRNA decoded
on ribosomes (in the cytosol and on the ER)
69
what are ribosomes made from
a large subunit and a small subunit
70
what is the large subunit of a ribosome composed of
49 ribosomal proteins and 3 rRNA molecules
71
what is the small subunit of a ribosome made of
33 ribosomal proteins and 1 rRNA molecule
72
T/F a ribosome is an enzyme
TRUE: it catalyzes the formation of covalent bonds between amino acids when making proteins (sometimes called a ribozyme)
73
what are the binding sites within a ribosome
there are 3 sites for tRNA (spanning both large and small subunits - A P E) and one site for mRNA (only in the small subunit)
74
how many steps does translation have and what are they
4 steps
75
what is the first step of translation
tRNA carrying an amino acid will enter the A site and stay if it has the correct anticodon
76
what is the second step of translation
the amino acid at the top of the tRNA that was at the P site is linked to the amino acid on top of tRNA at the A site, and then is removed from the tRNA that it was on to become freely moving as part of the protein chain
77
what is the third step of translation
the large subunit shifts to the right to make the P and A sites turn into E and P sites
78
what is the fourth step of translation
the small subunit catches up with the large subunit to shift over the mRNA that is bound in it, so that the next codon can be attached to a tRNA in the A site. the tRNA that was in site E is ejected before another tRNA attaches to site A. this is the last step and then step 1 will start again
79
what are the two things needed to start protein synthesis
translation initiation factors and a special initiator tRNA
80
what does the initiator tRNA do
it binds at the 5' cap of the mRNA and then is used to scan for the start codon AUG methionine
81
what happens when the initiator tRNA finds the start codon
the translation initiator factors get ejected and the large ribosome subunit gets added, and the protein chain gets started with the methionine to begin
82
how does protein translation stop
the stop codon has a special tRNA anticodon that doesn't get added to the protein amino acid chain but tells the ribosome to eject itself
83
what is different about prokaryotic mRNA molecules that code for protein
there are multiple different ribosome binding sites with multiple start codons so there can be several proteins created from one single mRNA at the same time
84
T/F there can be multiple ribosome translating a mRNA molecule of a eukaryotic cell at once
TRUE: these would create only 1 protein each, but they would all be the same protein just at different steps along the way
85
what helps regulate the amount of protein in a cell
controlled protein breakdown - proteasome with proteases that breakdown the proteins
86
what is the protein marker that tells the proteasome that a protein is ready to be degraded
the polyubiquitin chain is added and looked for when a protein goes into the proteasome
87
where does regulation of proteins happen
any steps between DNA replication and protein delivery can regulation happen
88
what are four ways that proteins could need to be modified before they become fully functional
they could need folding, phosphorylation, glycosylation, and binding to other proteins
89
what is the evolutionary theory behind RNA and DNA
there was an RNA world that came before DNA was around where RNA would've stored genetic information and started chemical reactions
90
why are cell membranes important
they are able to make the molecular composition of inside a cell differentiate from whats outside the cell
91
what are three functions of the cell membrane
receive information, import/export small molecules, move/expand flexibly
92
why are the internal membranes in eukaryotic cells important
they enclose different organelles and other compartments that may require different pHs or ion concentrations to function
93
what is the cell membrane made of
a lipid bilayer with proteins in it
94
what is the structure of a phospholipid
hydrophilic head and 2 hydrophobic tails
95
what is the structure of phosphatidylcholine
this is the most common phospholipid in cell membranes
head:
- choline
- phosphate
between:
- glycerol
tails:
- hydrocarbon tails
- double bond kinks and is unsaturated
- regular straight tail is saturated
96
what does it mean to be amphipathic
hydrophobic and hydrophilic on opposite ends
97
what is the energetically favorable position for a phospholipid bilayer
a closed sphere sealed conformation where the hydrophilic heads are on the outside
98
T/F lipid bilayer is flexible
TRUE: it's flexible in 2 dimensions
99
what ways are the lipid bilayers flexible in
1. lateral diffusion (can move side to side)
2. flexion (the legs have space to wiggle)
3. rotation (each individual phospholipid is able to spin on it's own axis)
4. sometimes they will flip flop sides but this is rare
100
what determines how fluid a bilayer is
the composition
ex: if it contains cholesterol
101
what is the structure of cholestoral
hydrophilic head group, rigid steroid ring structure, hydrophobic hydrocarbon tail
102
where does cell membrane assembly begin
in the ER
103
how do new cell membranes begin to get synthesized
the ER has a starting lipid bilayer, which then new phospholipids are added to the cytosolic half (the outside half)
104
what does scramblase do
once the phospholipids have been added to the cytosolic side, the scramblase randomly switches some of these to the inside side to even out the number on each side
105
what does flippase do
this switches specific phospholipids to the inside or outside side because some have certain parameters
- this is sometimes what can add a final curve to the membrane when there's an uneven number of cytosolic vs noncytosolic side.
106
where is scramblase used and where is flippase used
scramblase is in ER, flippase is in the golgi apparatus
107
T/F when membranes are transported, they tend to flip inside out on the way
FALSE: they retain their original orientation (outside phospholipids stay outside, inside ones stay toward the lumen) even during transport and when attaching to other membranes
108
what two lipids are distributed asymmetrically in the bilayer of animal cells
glycolipids are concentrated on the extracellular layer and the phospholipids are found on the cytosolic layer
109
what are some common plasma membrane proteins
transporters, channels, anchors, receptors, enzymes
110
what do transporters do
they use conformation changes to let things go through the membrane -- can be passive or active
111
what do channels do
they allow small molecules to enter/exit the membrane freely because they are passive
112
what is an anchor
this holds things inside or outside the membrane in specific conformations, and they are attached to the membrane for stability
113
what are receptors
these receive signals from outside the cell and send the message to the inside of the membrane
114
what are the different ways that a membrane protein can span the membrane
transmembrane, monolayer-associated, lipid-linked, protein-attached
115
what does it mean for a protein to be transmembrane attached to the membrane
where the protein has segments inside and outside of the membrane
- can be alpha helix or beta sheet barrel
116
what does it mean for a protein to be monolayer associated to the membrane
crossing over halfway through the membrane, but returning back to the same side of the membrane (not fully crossing the whole membrane) in a sideways alpha helix
117
what does it mean for a protein to be lipid-linked to the membrane
where the protein is connected to a lipid that is within the membrane, but the protein itself doesn't cross the surface
118
what does it mean for a protein to be protein-attached to the membrane
where there are two proteins, and the membrane crossing protein is connected to a peripheral protein which is not touching the membrane.
119
if a protein were to want to cross the membrane, what conformation is best and why
alpha helix because the hydrophobic side chains contact the hydrophobic tails and the hydrophilic parts of the backbone line the interior
120
what is a transmembrane hydrophilic pore
a group of 5 amphipathic alpha helices make a circle with the hydrophilic side chains on the inside to line the channel and the hydrophobic side chains on the outside to connect with the hydrophobic tails of the phospholipids
121
what does a detergent do and what is it's structure
it has a hydrophilic and hydrophobic end, and this is used to disrupt the bilayer by releasing membrane proteins
122
what is a cell cortex
this is a structure that reinforces the plasma membrane inside the cell. this lies under the membrane and contains spectrin and actin to make the shape structurally stable
123
what experiment showed that plasma membrane proteins can move freely laterally (around) the membrane
when a hybrid cell of mouse and human membrane was left for multiple minutes, the membrane proteins ended up being scattered along the membrane instead of staying half and half
124
how is lateral mobility---diffusion---of membrane proteins restricted (4 ways)
1. tethered to cell cortex inside the cell
2. tether to extracellular molecules outside the cell
3. connected to proteins on the surface of another cell
4. there can be diffusion barriers that restrict how far a protein can travel on the membrane
125
what is the FRAP photobleaching method
this measure the rate of lateral diffusion when a few proteins are bleached. it measures the time it takes for the proteins to diffuse from that area laterally, and start recovering back to all being unbleached.
126
what do the different patterns of diffusion show (really wide path, mid path, practically no path)
- really wide expansive path means that the protein is free to diffuse wherever it wants in the membrane
- medium sized restricted path is a protein that is within a membrane domain created by barriers but there is still movement within this area
- the practically no movement path is a protein that is tethered to the cytoskeleton or cell cortex and is basically immobile
127
what are all eukaryotic cells coated with
carbohydrates (connected to the bilayer or the proteins)
128
why are the membrane carbohydrates important
they help with cell-to-cell recognition especially when they bind to specific lectins that can recognize the carbohydrates and what the cell is/isn't needed for
129
what is selective transport
this facilitates the passive diffusion of specific molecules, or actively pumps specific molecules, into or out of the cell
130
what type of bilayer is impermeable to most water-soluble molecules
a protein-free artificial lipid bilayer, ex: liposome
131
what determines the rate at which a molecule crosses a protein-free, artificial lipid bilayer by simple diffusion, and what are some examples
the size and solubility of the molecule
- small nonpolar molecules travel fastest
- small uncharged polar molecules can get through but not always
- large uncharged polar molecules rarely get through but it can happen
- ions never get through
132
what are lipid bilayers always impermeable to
ions and most uncharged polar molecules
133
T/F channels are always open
FALSE: sometimes they can be gated which changes the ability for specific molecules and ions to pass the membrane
134
T/F transporters are very selective and transfer solutes very fast
FALSE: transporters are very selective, but they actually transport the solutes at a much slower rate than channels
135
is there more Na+ inside or outside the cell
more outside
136
is there more K+ inside the cell or outside
inside
137
is there more H+ inside or outside the cell
more inside (lower pH inside 7.2 vs 7.4 outside)
138
is there more Cl- inside or outside the cell
outside
139
what creates the membrane potential (voltage)
the difference in concentrations of the ions across the cell membrane
140
what is active vs passive transport
passive is channels and some transporters that regulate what solutes cross by themselves. active is transports that use energy or other binding factors to make certain solutes cross
-passive transport is down concentration gradient
-active transport is against the concentration gradient
141
what is a concentration gradient
more inside less outside means solutes will favor wanted to even this out and will bring flow more outside to get there
142
T/F active transport requires energy input
TRUE: usually in the form of ATP
143
what is the electrochemical gradient
the net driving force of what direction a solute is going to move based on the strength of the voltage and the concentration gradients
144
how does water diffuse
diffuses rapidly through aquaporin channels in the plasma membrane of some cells
145
what is osmotic swelling
most cases, osmosis drives water into the cells based on the fact that the solute concentration within cells is usually higher than outside, so water wants to enter to even out the concentrations (dilute the solute inside to match the outside), so this could create too much water that swells inside the cell
146
how do some cells avoid osmotic swelling
- protozoans discharge vacuoles filled with water
- animal cells remove the ions
- plant cells have really thick cell walls that don't let as much water in, so they hold the vacuole inside and use it as structural support
147
T/F each membrane contains many different sets of transporters
TRUE: each membrane has their own characteristic set of transporters that regulate their specific needs for solutes inside and outside the cell
148
what direction does passive transport move solutes
along its electrochemical gradient
149
how many conformation changes does the transporter have
3 - open in, closed, open out
150
T/F: a transporter can only make solutes go one direction
FALSE: a transporter allows solutes to travel both ways, and this happens when reaching equilibrium regardless of the concentration gradient bc some will still end up moving the opposite way even if its not with the gradient
151
what do pumps do
they actively transport solutes against the electrochemical gradient
152
what are three ways that active transport will get energy to move a solute against the electrochemical gradient
1. coupling with a solute that will be going down the gradient
2. using atp to force the pump to go against gradient
3. using light energy to open the transporter and push against gradient
153
how does the Na+ pump work
this uses ATP energy in animal cells to expel Na+ from the cell and bring K+ into the cell. both are moving against their electrochemical gradients. the Na+ goes in the protein and is pushed out the other side and the K+ goes in and is pushed into the cell to bring back to the Na+ going in the protein.
154
how many K+ come in and how many Na+ go out when the Na+ pump goes
3 Na+ get pushed out, and 2 K+ get pushed in
155
why is the Na+ pump useful
the cell wants to have a lot of K+ inside the cell and doesn't want to have a lot of Na+ in the cell
156
why is a high concentration of Na+ outside the cell beneficial
this is a source of potential energy outside the cell that can be used to do work
157
what does the Ca2+ pump do
this is in muscle cells to keep the inside Ca2+ concentration low by pumping it into a sarcoplasmic reticulum
158
what is uniport transport
one solute is passively transporting in one direction
159
what is antiport transport
a coupled transport that has the two solutes going in opposite directions across the membrane
160
what is symport transport
a couples transport that has the two solutes going in the same direction across the membrane
161
T/F some transporters need multiple specific binding sites to be occupied before it will switch conformations
TRUE: such as an Na+ gradient transport that also helps drive glucose against it's concentration gradient
162
T/F animal cells use Na+ symport transporters to bring other solutes across the membranes
TRUE: this helps the cell bring in and push out solutes that should/shouldn't be there
163
T/F in plant cells, there are symports that push H+ into the cell wall
TRUE: this helps regulate the internal environment of the cell
164
what are ion channels selective of
ion-selective and are often gated
165
what is selectivity of ion channels largely based on
charge and size
166
how does an ion channel let a specific ion in
the ion will shed it's water shell when entering the tunnel, and then the polar molecules that line the walls will attach to it if it's the correct size and push it through
167
what molecular group lines the walls of the K+ ion channel
carbonyl groups
168
are ions channels or transporters faster
ion channels because they let through more than 1 million ions per second whereas the transporter has to change conformations each time an ion wants to pass
169
where is the membrane potential calculated from
the ions that are closely lining the membrane determine the membrane potential
170
what plays a large role in determining the membrane potential in animal cells
the K+ leak channels and K+ concentration gradient that help the K+ ions move/not move across the membrane
171
what does the nernst equation tell us
when at equilibrium, the membrane potential (V) is equal to 62 x the log of ([conc of ion outside] / [conc of ion inside]) which tells us the membrane potential which is the force tending to drive an ion across a membrane
172
what technique is used to study and monitor ion channel activity
a patch clamp recording which is taking a single channel and removing it, giving it a current of electricity and seeing how long it takes for ions to get through to a specific concentration
- tells us when the gates are open vs closed based on the currents going through it
173
what are the three ways that an ion channel can be gated
mechanically gated, ligand-gated (outside or inside), voltage gated
174
what is an example of a mechanically gated ion channel and what does it mean
it means that something is physically moving the two gates apart to open the channel.
- example is in our ear, the stereocilia tilt when vibrating and this opens the gates to let ions in
- example 2 is when pressure stretches the pores to be more straight, the gate opens
175
what is an action potential
allows rapid long-distance communication along axons
176
what is the structure of a neuron
cell body, axon, dendrites,
177
what does a dendrite do
receives signals from the axons of other neurons
178
what does the axon do
sends signals away to other neurons and to target cells
179
how do researchers typically study axons
using a squid that has a giant axon that they can then record ion channels and other action potential details with
- scientists can then study nerve cell excitability using this isolated axon because they can insert an electrode to measure the action potential spikes
- they can remove the cytoplasm in the axon and then replace it with other things to study the effects of Na+ concentration on action potential
180
what are action potentials mediated by
the voltage-gated cation channels
- without channels, the action potential doesn't cross the threshold amount
181
what opens a voltage-gated Na+ channel
the membrane potential (voltage) on the opposite sides can cause the channel to be open, closed, or inactivated
182
what channels open when the action potential is moving down an axon
the voltage-gated Na+ channels open when the action potential arrives at it's location and Na+ begins to flow in
183
when does a voltage-gate Na+ channel become inactivated
it will take it's cleft cleave foot lock and block the doorway once the action potential has passed in order to keep this favorable Na+ ratio inside the axon
then it returns to the closed state after the action potential has left
184
T/F action potential propagates along the length of an axon
TRUE: it moves along through the axon depolarizing the spot it's at by the Na+ channels opening
185
how does an axon return to it's resting membrane potential after an action potential has passed
the K+ channels open up after the axon has passed in order to return the membrane potential to have more +++ on outside and - - - on inside by flowing the K+ ions outside of the axon
186
T/F multiple action potentials can propagate down an axon at once
FALSE: the first one must finish it's path and be passed on before another stimulus can be produced.
- this is because the Na+ channels have to return to the closed state instead of the inactivated state before it can go to the open state again for a new action potential
187
what is it called when an axon is waiting for the Na+ channels to return to their closed state in action potential occurrences
the membrane is resistant or refractory to stimulation while it waits for the conformation change of Na+ channels from inactivated to closed
188
what are voltage gated Ca2+ channels used for
in the nerve terminals (synaptic cleft to the dendrite cell), these channels convert electrical signals into chemical signals
189
how does a voltage gated Ca2+ channel turn an electrical signal into a chemical signal
when the Ca2+ channel opens when the neurotransmitters arrive, the synaptic vesicle fuses with the presynaptic nerve terminal and so the neurotransmitters are released into the synaptic cleft (called exocytosis).
190
what happens to the neurotransmitters once they have been released into the synaptic cleft
they become ligands that bind to the ligand ion channels, which turns the chemical signal back into an electrical one (ion) to be used as an action potential
191
what can be either excitatory or inhibitory
neurotransmitters
192
what does it mean to have an excitatory neurotransmitter
when the neurotransmitter binds to the ligand channel and lets Na+ flow in, the membrane potential gets closer to the threshold and would get closer to triggering an action potential
193
what does it mean for a neurotransmitter to be inhibitory
the neurotransmitter as a ligand binds to a Cl- channel which makes the membrane potential further away from the threshold voltage and makes it harder to trigger an action potential
194
T/F as long as there is at least one excitatory signal, an action potential will be triggered
FALSE: the determination of whether an action potential will be triggered or not is based on the sum of all the excitatory and inhibitory signals
195
T/F an experiment was done where a light was turned on/off that affected a mouse's behavior
TRUE: this light turned on would not inhibit anything, but when it was turned off, the neurons in that part of the brain would affect the light-gated ion channels and alter the behavior of the mouse
- this one used the hypothalamus neurons to make the mouse attack the rubber glove
