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exam 3 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what directs the synthesis of proteins

A

genetic information

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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

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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

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4
Q

what bonds hold the backbone of RNA together

A

phosphodiester bonds

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5
Q

how many strands does DNA have

A

2

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6
Q

how many strands does RNA have

A

1

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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

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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

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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

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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

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11
Q

what protein transcribes the DNA into RNA

A

RNA polymerase

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12
Q

what direction is RNA synthesized in

A

5’ to 3’

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13
Q

what direction is the template strand being read in

A

3’ to 5’

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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

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15
Q

what does messenger RNA (mRNA) do

A

codes for proteins

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16
Q

what does ribosomal RNA (rRNA) do

A

forms the core of the ribosome’s structure and catalyzes protein synthesis

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17
Q

what does transfer RNA (tRNA) do

A

serves as adaptors between mRNA and amino acids during protein synthesis

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18
Q

what does the promoter on DNA do

A

it tells the RNA polymerase where to begin the gene transcription

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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

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20
Q

what does the terminator on DNA do

A

it tells the RNA polymerase where to stop the transcription of the gene

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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

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22
Q

how many RNA polymerases are there

A

3

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23
Q

what does RNA polymerase I do

A

it transcribes most rRNA genes

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24
Q

what does RNA polymerase II do

A

it transcribes all protein genes

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25
Q

what does RNA polymerase III do

A

it transcribes tRNA and other small RNAs

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26
Q

what does RNA polymerase II need to start transcription

A

general transcription factors

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27
Q

what is the TATA box

A

the promoter that tells the polymerase where to begin transcription

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28
Q

how is the TATA box read

A

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

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29
Q

what happens after the TATA box is read

A

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

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30
Q

what does the TFIIB do

A

this is what goes along the DNA strand and hold the TBP

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31
Q

what does the TBP do

A

this is the TATA binding protein that is on the TFIIB and reads the TATA sequence

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32
Q

what does the TFIIB do

A

this is the first general transcription factor that attaches to the kinked strand once the tata box is read

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33
Q

what does the TFIIH do

A

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

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34
Q

generally, what does TFIIF do

A

helps the RNA polymerase II connect onto the other transcription factors before it starts transcription

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35
Q

generally what does the TFIIE do

A

this is part of the formation and activation of the RNA polymerase II

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36
Q

what is the location of the TATA box

A

-30

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37
Q

what general transcription factor binds at -35

A

TFIIB

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38
Q

what general transcription factor binds at -30

A

TBP which is within TFIID

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39
Q

how does RNA polymerase II transcribe the DNA that is wrapped around a histone (in a nucleosome formation)

A

elongation factors

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40
Q

where are eukaryotic mRNAs processed

A

in the nucleus

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41
Q

what 3 things can help modify an RNA as it is being transcribed

A

capping factors, splicing factors, polyadenylation factors

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42
Q

what are the special structures on mRNA

A

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

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43
Q

what does the capping factor do to the RNA

A

this makes it start to become mRNA bc it adds a cap to the 5’ end of the RNA that is being created

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44
Q

what does the polyadenylation factor do to the RNA

A

this makes the poly-A tail on the 3’ end of the mRNA

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45
Q

when are the cap and poly-A tail added

A

after transcription has finished

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46
Q

what is the structure of the 5’ cap on mRNA

A

7-methylguanosine and a triphosphate bridge

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47
Q

what is an intron

A

a non coding gene in a eukaryotic DNA strand

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48
Q

what is an exon

A

a coding sequence of DNA in a eukaryotic cell

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49
Q

what turns the pre-mRNA into mRNA

A

the introns are removed by splicing factors to turn the pre mRNA into regular mRNA
- the untranslated regions stay at the ends

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50
Q

how does RNA splicing work

A

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

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51
Q

T/F splicing has to happen after synthesis

A

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

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52
Q

what happens to the intron lariats

A

they will eventually get degraded into the nucleus

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53
Q

what is an alternative splicing mean

A

when a pre-mRNA actually has an exon removed to form another type of mRNA

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54
Q

where do mRNAs have to go before they can be translated

A

they have to go from the nucleus where they were made and be exported to the cytosol through pores in the nuclear envelope

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55
Q

what does the poly-A binding protein and the cap binding protein do

A

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

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56
Q

T/F prokaryotes are easier to produce mRNA in than eukaryotes

A

TRUE: prokaryotic cells have transcription and translation occurring in the same location in the cell, so translation can happen before transcription even finishes

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57
Q

what happens to all mRNAs eventually

A

they degrade into RNases

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58
Q

what is the start codon for all proteins

A

M methionine - AUG

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59
Q

what is the central dogma

A

DNA to RNA to PROTEIN through replication transcription translation

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60
Q

how many reading frames are there

A

3

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61
Q

what is a frame shift mutation

A

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

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62
Q

how did researchers decipher genetic code

A

they put different mRNAs into a translation system and saw the different types of polypeptides that were produced

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63
Q

what shape do tRNA molecules usually form into

A

a clover

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64
Q

what is the anticodon

A

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

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65
Q

what does the tRNA do

A

they are adaptors that link the amino acids to the codons

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66
Q

what enzyme couples the tRNA to the correct amino acid

A

aminoacyl-tRNA synthetase

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67
Q

what does the aminoacyl-tRNA synthetase do

A

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

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68
Q

where is mRNA decoded

A

on ribosomes (in the cytosol and on the ER)

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69
Q

what are ribosomes made from

A

a large subunit and a small subunit

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70
Q

what is the large subunit of a ribosome composed of

A

49 ribosomal proteins and 3 rRNA molecules

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71
Q

what is the small subunit of a ribosome made of

A

33 ribosomal proteins and 1 rRNA molecule

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72
Q

T/F a ribosome is an enzyme

A

TRUE: it catalyzes the formation of covalent bonds between amino acids when making proteins (sometimes called a ribozyme)

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73
Q

what are the binding sites within a ribosome

A

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)

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74
Q

how many steps does translation have and what are they

A

4 steps

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75
Q

what is the first step of translation

A

tRNA carrying an amino acid will enter the A site and stay if it has the correct anticodon

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76
Q

what is the second step of translation

A

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

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77
Q

what is the third step of translation

A

the large subunit shifts to the right to make the P and A sites turn into E and P sites

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78
Q

what is the fourth step of translation

A

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

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79
Q

what are the two things needed to start protein synthesis

A

translation initiation factors and a special initiator tRNA

80
Q

what does the initiator tRNA do

A

it binds at the 5’ cap of the mRNA and then is used to scan for the start codon AUG methionine

81
Q

what happens when the initiator tRNA finds the start codon

A

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
Q

how does protein translation stop

A

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
Q

what is different about prokaryotic mRNA molecules that code for protein

A

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
Q

T/F there can be multiple ribosome translating a mRNA molecule of a eukaryotic cell at once

A

TRUE: these would create only 1 protein each, but they would all be the same protein just at different steps along the way

85
Q

what helps regulate the amount of protein in a cell

A

controlled protein breakdown - proteasome with proteases that breakdown the proteins

86
Q

what is the protein marker that tells the proteasome that a protein is ready to be degraded

A

the polyubiquitin chain is added and looked for when a protein goes into the proteasome

87
Q

where does regulation of proteins happen

A

any steps between DNA replication and protein delivery can regulation happen

88
Q

what are four ways that proteins could need to be modified before they become fully functional

A

they could need folding, phosphorylation, glycosylation, and binding to other proteins

89
Q

what is the evolutionary theory behind RNA and DNA

A

there was an RNA world that came before DNA was around where RNA would’ve stored genetic information and started chemical reactions

90
Q

why are cell membranes important

A

they are able to make the molecular composition of inside a cell differentiate from whats outside the cell

91
Q

what are three functions of the cell membrane

A

receive information, import/export small molecules, move/expand flexibly

92
Q

why are the internal membranes in eukaryotic cells important

A

they enclose different organelles and other compartments that may require different pHs or ion concentrations to function

93
Q

what is the cell membrane made of

A

a lipid bilayer with proteins in it

94
Q

what is the structure of a phospholipid

A

hydrophilic head and 2 hydrophobic tails

95
Q

what is the structure of phosphatidylcholine

A

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
Q

what does it mean to be amphipathic

A

hydrophobic and hydrophilic on opposite ends

97
Q

what is the energetically favorable position for a phospholipid bilayer

A

a closed sphere sealed conformation where the hydrophilic heads are on the outside

98
Q

T/F lipid bilayer is flexible

A

TRUE: it’s flexible in 2 dimensions

99
Q

what ways are the lipid bilayers flexible in

A
  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
Q

what determines how fluid a bilayer is

A

the composition
ex: if it contains cholesterol

101
Q

what is the structure of cholestoral

A

hydrophilic head group, rigid steroid ring structure, hydrophobic hydrocarbon tail

102
Q

where does cell membrane assembly begin

A

in the ER

103
Q

how do new cell membranes begin to get synthesized

A

the ER has a starting lipid bilayer, which then new phospholipids are added to the cytosolic half (the outside half)

104
Q

what does scramblase do

A

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
Q

what does flippase do

A

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
Q

where is scramblase used and where is flippase used

A

scramblase is in ER, flippase is in the golgi apparatus

107
Q

T/F when membranes are transported, they tend to flip inside out on the way

A

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
Q

what two lipids are distributed asymmetrically in the bilayer of animal cells

A

glycolipids are concentrated on the extracellular layer and the phospholipids are found on the cytosolic layer

109
Q

what are some common plasma membrane proteins

A

transporters, channels, anchors, receptors, enzymes

110
Q

what do transporters do

A

they use conformation changes to let things go through the membrane – can be passive or active

111
Q

what do channels do

A

they allow small molecules to enter/exit the membrane freely because they are passive

112
Q

what is an anchor

A

this holds things inside or outside the membrane in specific conformations, and they are attached to the membrane for stability

113
Q

what are receptors

A

these receive signals from outside the cell and send the message to the inside of the membrane

114
Q

what are the different ways that a membrane protein can span the membrane

A

transmembrane, monolayer-associated, lipid-linked, protein-attached

115
Q

what does it mean for a protein to be transmembrane attached to the membrane

A

where the protein has segments inside and outside of the membrane
- can be alpha helix or beta sheet barrel

116
Q

what does it mean for a protein to be monolayer associated to the membrane

A

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
Q

what does it mean for a protein to be lipid-linked to the membrane

A

where the protein is connected to a lipid that is within the membrane, but the protein itself doesn’t cross the surface

118
Q

what does it mean for a protein to be protein-attached to the membrane

A

where there are two proteins, and the membrane crossing protein is connected to a peripheral protein which is not touching the membrane.

119
Q

if a protein were to want to cross the membrane, what conformation is best and why

A

alpha helix because the hydrophobic side chains contact the hydrophobic tails and the hydrophilic parts of the backbone line the interior

120
Q

what is a transmembrane hydrophilic pore

A

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
Q

what does a detergent do and what is it’s structure

A

it has a hydrophilic and hydrophobic end, and this is used to disrupt the bilayer by releasing membrane proteins

122
Q

what is a cell cortex

A

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
Q

what experiment showed that plasma membrane proteins can move freely laterally (around) the membrane

A

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
Q

how is lateral mobility—diffusion—of membrane proteins restricted (4 ways)

A
  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
Q

what is the FRAP photobleaching method

A

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
Q

what do the different patterns of diffusion show (really wide path, mid path, practically no path)

A
  • 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
Q

what are all eukaryotic cells coated with

A

carbohydrates (connected to the bilayer or the proteins)

128
Q

why are the membrane carbohydrates important

A

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
Q

what is selective transport

A

this facilitates the passive diffusion of specific molecules, or actively pumps specific molecules, into or out of the cell

130
Q

what type of bilayer is impermeable to most water-soluble molecules

A

a protein-free artificial lipid bilayer, ex: liposome

131
Q

what determines the rate at which a molecule crosses a protein-free, artificial lipid bilayer by simple diffusion, and what are some examples

A

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
Q

what are lipid bilayers always impermeable to

A

ions and most uncharged polar molecules

133
Q

T/F channels are always open

A

FALSE: sometimes they can be gated which changes the ability for specific molecules and ions to pass the membrane

134
Q

T/F transporters are very selective and transfer solutes very fast

A

FALSE: transporters are very selective, but they actually transport the solutes at a much slower rate than channels

135
Q

is there more Na+ inside or outside the cell

A

more outside

136
Q

is there more K+ inside the cell or outside

A

inside

137
Q

is there more H+ inside or outside the cell

A

more inside (lower pH inside 7.2 vs 7.4 outside)

138
Q

is there more Cl- inside or outside the cell

A

outside

139
Q

what creates the membrane potential (voltage)

A

the difference in concentrations of the ions across the cell membrane

140
Q

what is active vs passive transport

A

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
Q

what is a concentration gradient

A

more inside less outside means solutes will favor wanted to even this out and will bring flow more outside to get there

142
Q

T/F active transport requires energy input

A

TRUE: usually in the form of ATP

143
Q

what is the electrochemical gradient

A

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
Q

how does water diffuse

A

diffuses rapidly through aquaporin channels in the plasma membrane of some cells

145
Q

what is osmotic swelling

A

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
Q

how do some cells avoid osmotic swelling

A
  • 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
Q

T/F each membrane contains many different sets of transporters

A

TRUE: each membrane has their own characteristic set of transporters that regulate their specific needs for solutes inside and outside the cell

148
Q

what direction does passive transport move solutes

A

along its electrochemical gradient

149
Q

how many conformation changes does the transporter have

A

3 - open in, closed, open out

150
Q

T/F: a transporter can only make solutes go one direction

A

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
Q

what do pumps do

A

they actively transport solutes against the electrochemical gradient

152
Q

what are three ways that active transport will get energy to move a solute against the electrochemical gradient

A
  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
Q

how does the Na+ pump work

A

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
Q

how many K+ come in and how many Na+ go out when the Na+ pump goes

A

3 Na+ get pushed out, and 2 K+ get pushed in

155
Q

why is the Na+ pump useful

A

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
Q

why is a high concentration of Na+ outside the cell beneficial

A

this is a source of potential energy outside the cell that can be used to do work

157
Q

what does the Ca2+ pump do

A

this is in muscle cells to keep the inside Ca2+ concentration low by pumping it into a sarcoplasmic reticulum

158
Q

what is uniport transport

A

one solute is passively transporting in one direction

159
Q

what is antiport transport

A

a coupled transport that has the two solutes going in opposite directions across the membrane

160
Q

what is symport transport

A

a couples transport that has the two solutes going in the same direction across the membrane

161
Q

T/F some transporters need multiple specific binding sites to be occupied before it will switch conformations

A

TRUE: such as an Na+ gradient transport that also helps drive glucose against it’s concentration gradient

162
Q

T/F animal cells use Na+ symport transporters to bring other solutes across the membranes

A

TRUE: this helps the cell bring in and push out solutes that should/shouldn’t be there

163
Q

T/F in plant cells, there are symports that push H+ into the cell wall

A

TRUE: this helps regulate the internal environment of the cell

164
Q

what are ion channels selective of

A

ion-selective and are often gated

165
Q

what is selectivity of ion channels largely based on

A

charge and size

166
Q

how does an ion channel let a specific ion in

A

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
Q

what molecular group lines the walls of the K+ ion channel

A

carbonyl groups

168
Q

are ions channels or transporters faster

A

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
Q

where is the membrane potential calculated from

A

the ions that are closely lining the membrane determine the membrane potential

170
Q

what plays a large role in determining the membrane potential in animal cells

A

the K+ leak channels and K+ concentration gradient that help the K+ ions move/not move across the membrane

171
Q

what does the nernst equation tell us

A

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
Q

what technique is used to study and monitor ion channel activity

A

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
Q

what are the three ways that an ion channel can be gated

A

mechanically gated, ligand-gated (outside or inside), voltage gated

174
Q

what is an example of a mechanically gated ion channel and what does it mean

A

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
Q

what is an action potential

A

allows rapid long-distance communication along axons

176
Q

what is the structure of a neuron

A

cell body, axon, dendrites,

177
Q

what does a dendrite do

A

receives signals from the axons of other neurons

178
Q

what does the axon do

A

sends signals away to other neurons and to target cells

179
Q

how do researchers typically study axons

A

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
Q

what are action potentials mediated by

A

the voltage-gated cation channels
- without channels, the action potential doesn’t cross the threshold amount

181
Q

what opens a voltage-gated Na+ channel

A

the membrane potential (voltage) on the opposite sides can cause the channel to be open, closed, or inactivated

182
Q

what channels open when the action potential is moving down an axon

A

the voltage-gated Na+ channels open when the action potential arrives at it’s location and Na+ begins to flow in

183
Q

when does a voltage-gate Na+ channel become inactivated

A

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
Q

T/F action potential propagates along the length of an axon

A

TRUE: it moves along through the axon depolarizing the spot it’s at by the Na+ channels opening

185
Q

how does an axon return to it’s resting membrane potential after an action potential has passed

A

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
Q

T/F multiple action potentials can propagate down an axon at once

A

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
Q

what is it called when an axon is waiting for the Na+ channels to return to their closed state in action potential occurrences

A

the membrane is resistant or refractory to stimulation while it waits for the conformation change of Na+ channels from inactivated to closed

188
Q

what are voltage gated Ca2+ channels used for

A

in the nerve terminals (synaptic cleft to the dendrite cell), these channels convert electrical signals into chemical signals

189
Q

how does a voltage gated Ca2+ channel turn an electrical signal into a chemical signal

A

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
Q

what happens to the neurotransmitters once they have been released into the synaptic cleft

A

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
Q

what can be either excitatory or inhibitory

A

neurotransmitters

192
Q

what does it mean to have an excitatory neurotransmitter

A

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
Q

what does it mean for a neurotransmitter to be inhibitory

A

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
Q

T/F as long as there is at least one excitatory signal, an action potential will be triggered

A

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
Q

T/F an experiment was done where a light was turned on/off that affected a mouse’s behavior

A

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

biology (4 decks)

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