Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cell Bio (final)- test 1 +new > Lectures 27-30 (new) > Flashcards

Lectures 27-30 (new) Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What is visible light spectrum

A

segment of electromagnetic spectrum that human eye can view (colors)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

longer wavelength = ? (in regard to energy)

A

less energy carried

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

most energy is carried by (in regard to wavelength)

A

short wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is fluorescence

A

emission of light by a substance that has absorbed light or other reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

some excited proteins emit ___

A

light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how do fluorescent molecules work (how do they emit light)

A

absorb light (photon) at one wavelength and emit it at another longer wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is light also referred to as

A

Photon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens when a fluorescent molecule absorbs a photon

A

fluorescent molecule absorbs photon, is in excited state, emits photon/light at longer wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

when is fluorescence at its highest

A

at excitation peak

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

when is the most light emitted?

A

at emission peak

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

when does fluorescence occur (in regard to electron)

A

fluorescence occurs when electron returns to its ground state & emits a photon of light at a longer wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is photobleaching

A

too much exposure to light destroys the fluorochrome molecule (loss of fluoresce ability)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is immunofluorescence used for

A

method to localize molecules on fixed cells or tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe immunofluorescence (how it happens with antibodies)

A

primary antigen binds to antigen, secondary antibody w/marker coupled (marker fluoresces when binding happens)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are antibodies

A

proteins produced by vertebrate immune system as a defense against infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What fluorescent protein emits green light

A

GFP (green fluorescent protein)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what bioluminescent protein emits blue light

A

Aequorin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What works together to luminesce green

A

Aequorin & GFP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do Aequorin & GFP work to luminesce

A

Aequorin & GFP convert Ca2+-induced luminescent signals into green luminescence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

explain steps of green luminescence

A

ATP & Ca2+ binds to aequorin (exciting it), transmits light to GFP, GFP excites and emits green light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how does GFP work

A

absorbs blue light & emits green light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how can GFP be made? does it need additional groups/cofactors

A

it can be genetically encoded (chromophore is made by amino acids); it doesn’t need a prosthetic group or cofactor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what makes the GFP chromophore

A

amino acids (therefore, it is genetically encoded)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does GFP do direct visualization

A

GFP fuses to coding sequence of a gene of the target protein allows for direct visualization of protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how does GFP fusion to coding sequence of a gene change the sequence

A

original coding sequence (RNA): promoter site, protein, stop signal
GFP fused coding sequence (RNA: promoter site, protein, GFP (so the mRNA will be read and the protein will be coded for + the GFP protein that makes light)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How is GFP fused into RNA coding sequence used to visualize the target protein

A

put in blue light, in the dark we see the GFP emit green light (localizing the target protein)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is a peptide location signal

A

signal that directs something to a particular cell compartment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what can be added to GFP to direct it somewhere

A

peptide location signal can be added to GFP to direct to particular cell compartment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Where does NLS-GFP direct protein to

A

into nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

where does KDEL-GFP directed to go

A

into ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what do mutations in GFP result in

A

change absorption & emission colors (changes excitation & emission peaks)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what fluorescent properties can be changed due to mutation

A

brightness stability, maturation time (ex doesn’t emit light right away)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is RFP

A

protein that emits red light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What can fluorescent proteins do

A

track movement of proteins & cells in-vivo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what can a fluorescent indicator help us visualize

A

intracellular Ca2+ conc’s (more Ca2+ present = more bright light)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what is GCaMP? Function?

A

GFP Calmodulin Protein; measures Ca2+ conc (more = brighter light)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is Ca2+ imaging used for

A

monitoring activity of distinct neurons in brain tissue, in vivo (living thing)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what does a change in calcium mean (seen in calcium imaging)

A

change in Ca2+ = neuron activity (change in Ca2+ is observed by increase fluorescence when active)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

how does GFP fluorescence respond to pH changes

A

rapidly & reversibly; fluorescence intensity increases with increase in pH (more basic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what is photobleaching

A

photochemical alteration of a fluorophore, loses its ability to fluoresce

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is FRAP

A

Fluorescence recovery after photobleaching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what does FRAP tell us

A

indicates dynamics of a protein in living cell (i.e. how fast proteins move to recover)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

what are photoactivatable fluorescent proteins

A

fluorescent proteins that display unique changes in their spectral properties upon exposure to specific wavelength of light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what are the types of photoactivatable fluorescent proteins

A

irreversible: UV light goes from protein 1 to protein 2, which emits light (ex black to green, only green will ever be emitted)
photoconvertible: protein 1 can emit light or pass the UV light to protein 2, which can emit light of a diff wavelength (ex Green & red, could see either)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

do fluorescent proteins change color?

A

Yes, some florescent proteins change color overtime, so we can test the “age” of proteins & cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is FRET

A

fluorescence resonance energy transfer; technique to gauge distance between 2 chromophores (protein to protein binding)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

in proximity vs not, in regard to FRET

A

In proximity = FRET (proteins close enough to transfer UV excitation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Describe how FRET transfers UV excitation/light

A

first fluorescent protein is excited, excitation is transferred to protein close by, this protein emits light of its wavelength (ex: blue to yellow, both fluoresce, but blue fluoresces less bright)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

if not in proximity what protein fluoresces in FRET

A

the protein that receives UV excitation emits light (the protein far away is not excited)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

what can be used to make genetically encoded fluorescent biosensors? How?

A

FRET; proteins are linked by linker, if close together, energy is passes and second protein fluoresces (linker is bent when close together/flat when apart & first protein fluoresces)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

How do split GFP proteins form 1 GFP protein

A

when close together, they spontaneously assemble into functional protein (protein-protein interactions, cell-cell contacts)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What are the steps of Central Dogma

A

DNA goes through transcription to be mRNA, mRNA goes through translation (ribosome) to make protein (chain of peptides)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Where does transcription occur

A

nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

where does translation occur

A

cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What is hybridization

A

combination of 2 complementary single-stranded DNA or RNA & allowing them to form a double stranded molecule (thru base pairing)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What are the bases that pair together

A

A&T/U, C&G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

RNA hybridization allows detection of what

A

mRNA molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

types of RNA hybridization

A
  1. target hybridization (fluorophore attaches to oligonucleotide & glows)
  2. fluorescence imaging (view under microscope)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

what is the effect of injecting in single stranded RNA (for muscle protein) in parent

A

no effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

what is the effect of injecting dsRNA (codes for muscle protein) in parent

A

Twitching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

what does injection of dsRNA do

A

inhibit synthesis of specific proteins (destroys mRNA that would code for protein to be formed)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

injection of dsRNA promotes?

A

dsRNA promotes mRNA degradation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

RNA interference is?

A

RNAi is a mechanism of gene regulation (destroy mRNA, so a protein isn’t made)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

steps of RNAi

A

dsRNA injected, binds to protein Dicer which cleaves dsRNA into smaller fragments, one RNA strand is loaded into RISC complex (nuclease that degrades), RISC complex linked to mRNA strand by base pairing, mRNA cleaved & destroyed (no protein synthesized)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What is a Dicer

A

nuclease enzyme; cleaves dsRNA into small fragments called small interfering RNAs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

what are siRNAs

A

small interfering RNAs; small fragments of dsRNA (cut by Dicer)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

where does an siRNA go

A

a single strand of an siRNA goes into/becomes RISC complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

What binds ds siRNAs to RISC complex

A

Argonaute cleaves ds siRNA to be 1 strand and binds it to RISC complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

what does RISC stand for

A

RNA-induced silencing complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

what is RISC

A

complex of ribonucleic acid & RNA-binding proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

what is RISC composed of

A

Argonaute, RNA, RNA-binding proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

what does Argonaute do in RNAi

A

cleave ds siRNA and binds one strand to the RISC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

summary of steps of RNA interference

A

dsRNA cleaved into siRNA by Dicer, siRNA joins RISC, Argonaute cleaves siRNA into 1 strand, the RISC binds & degrades complementary mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

what is RNAi used for

A

defense against viruses & jumping genes (key for plants, worms, insects - bc they cannot make antibodies)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

viruses have what (DNA, RNA..?)

A

dsRNA - when it infects cell, it injects its RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

what is shRNA

A

mimics dsRNA in RNAi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

Review L28, S16

A

Review L28, S16

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

role of snRNA in RNAi

A

microRNA gene makes shRNA that mimics dsRNA, Dicer recognizes it as dsRNA & cleaves, sent to RISC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

how are genes of interest silenced

A

introduction of dsRNA (RNAi therapies)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

what does shRNA stand for? what does it do?

A

short hairpin RNA; artificial RNA molecule with a hairpin turn that mimics dsRNA molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

RNAi allows what to happen

A

removal of specific proteins in cells & tissues without affecting the genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

types of RNAi

A

therapeutic: remove malfunctioning proteins, destroy viruses
research: study functions of individual proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

how do pressure gated channels work? example?

A

opens in response to mechanical force; PIEZO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

what may cure Huntington’s Disease

A

RNAi; HD is caused by mutations in Huntingtin gene, they accumulate in neurons & cause brain damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

what does RNAi screen in cells tell us

A

identifies cell morphology proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

steps of RNAi screen

A
  1. identify interesting process (eg. cell morphology)
  2. get library of dsRNA that cover all the genes
  3. incubate cells w/specific dsRNA
  4. score the changes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

2 protein-protein interaction methods:

A

in the organism
-immunoprecipitations (separate proteins using antibodies),
-biotinylation (tag proteins with biotin)
-FRET or BIFC (diff fluorescence based approaches)
in unrelated organism system or test tube:
-GST-Pulldown (test binding in a test tube)
- Two-hybrid (bacteria or yeast)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

what are electrophoresis & western blot used for

A

detect proteins on a sample.
separate proteins by size in electrophoresis (small, - molecules move down gel fastest), using Phenol red dye in western blot reveals all proteins, using antibodies to detect specific proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

what do co-immunoprecipitation experiments detect

A

protein-protein interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

what is co-immunoprecipitation experiment (steps)

A
  1. Preparation of sample.
    -have mix of protein complexes and free proteins,
  2. Antibody capture
    -antibody recognize bait protein (a part of protein complex),
    -binding occurs & bead on antibody weighs down the complex,
  3. Washing & elution
    -unbound protein is removed, beads at bottom contain the bait protein with all interacting proteins,
  4. detection via Western Blot
    -reveal the proteins using Western Blot
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

Western Blot is what kind of experiment

A

co-immunoprecipitation experiment

92
Q

how many targets can we have with WB

A

1 target at a time, time-consuming

93
Q

how to tell from WB if proteins are interacting

A

when probing for 1 protein, another protein is detected (bar of molecular weight visible), it is interacting with the probed protein

94
Q

What is Liquid Chromatography-tandem mass spectrometry (LC-MS/MS)

A

co-immunoprecipitation experiment that allows identification of all proteins in the mix;
LC separates components of peptide mixture, MS/MS measures the mass-to-charge ratio (m/z) - from here search database to guess identity proteins from library of peptides

95
Q

what is done if there is no antibody? examples?

A

fuse protein to a tag (tag goes on terminal end of protein); His and FLAG are examples

96
Q

what is proximity biotinylation

A

method that uses a biotin ligase to mark proteins that are close (biotinylates proteins - permanent)

97
Q

steps of proximity biotinylation

A

-fuse the bait protein to biotin ligase (BirA)
-BirA add biotin to exposed lysines on neighboring proteins

98
Q

What is the addition of biotin called

A

biotinylation

99
Q

what is streptavidin

A

protein produced by streptomyces avidinii w/strong biotin-binding ability

100
Q

what does streptavidin do

A

depletes biotin; separates all biotinylated proteins

101
Q

what does a streptavidin column do

A

separate biotinylated proteins (they will remain in column bound to agarose bead & rest will flow out)

102
Q

what do fluorescence methods tell us

A

where the interaction happens

103
Q

what are donor and acceptor in FRET

A

donor transfers energy and acceptor receives transferred energy

104
Q

Pros & Cons of BIFC & Fret

A

Pro: single cell resolution or better, temporal resolution
Con: only 2 proteins at a time, time-consuming, need a fluorescence microscope

105
Q

explain two hybrid systems in yeast

A

the GAI4 protein is cut in 2 parts: AD & BD
AD fuses to Prey protein
BD fuses to Bait protein
If AD & BD are together (therefore Prey and Bait together), a functional GaI4 protein will form and activate transcription of the reporter gene (Gal4 is a transcription factor binds to the UAS sequence)

106
Q

A yeast two-hybrid (Y2H) experiment detects what

A

physical interactions of protein through the downstream activation of a reporter gene

107
Q

Y2H experiment: if prey and bait don’t interact, what happens?

A

no gene transcription occurs; interaction of bait and prey protein fusions will dictate reporter expression

108
Q

what does reporter gene do to yeast

A

turns yeast blue (can sequence the blue colonies to reveal the interacting proteins)

109
Q

parts of a neuron

A

cell body (contains nucleus), long axon, short branching dendrites (coming from cell body), terminal branches of axon (connects w/other neurons or muscle)

110
Q

fundamental task of neuron, or nerve cell?

A

to receive, integrate, conduct, and transmit signals

111
Q

what cells are neurons

A

discrete cells

112
Q

can neurons decide to transmit info or not

A

yes

113
Q

what do dendrites do

A

receive info from other neurons, pressure, heat

114
Q

is axon unidirectional or not

A

axon is unidirectional -> sends info to another neuron or muscle

115
Q

Membrane potential is what? what mV?

A

difference in the conc of ions on opposite sides of a membrane; -70 to -40mV

116
Q

what is depolarization? mV?

A

interior voltage becomes less negative (more positive); -70 to -60mV

117
Q

what is hyperpolarization? mV?

A

interior voltage becomes more negative; -70 to -80mV

118
Q

what does change in voltage mean

A

change in voltage is used as an intracellular signal

119
Q

what ions are usually outside cell more

A

Na+ & Cl-

120
Q

what ions are inside cell more

A

K+

121
Q

what is the membrane potential called when neuron is not active

A

resting potential

122
Q

What do excitatory signals open in neuron

A

Na+ channels, depolarizes membrane

123
Q

what do inhibitory signals open in neuron

A

Cl- channels or K+ channels, Hyperpolarizing membrane (suppresses firing)

124
Q

does membrane potential propagate through membrane

A

yes, neighboring voltage-gated ion channels become depolarized, once reaches threshold, AP starts, repolarization occurs when K+ channels open (delayed opening), depolarization spreads forward down axon

125
Q

what channels are on axon

A

voltage-gated ion channels

126
Q

what is the part of axon that begins the action potential

A

axon hillock (first voltage-gated ion channel on axon)

127
Q

what transmits signals in wave through nervous system? (neurons)

A

Voltage-gated Na+ channels

128
Q

if voltage difference is high (membrane), are Na+ channels open or closed? at low?

A

tightly closed; low voltage difference channels open and allow Na+ to pass

129
Q

At what voltage difference do Na+ channels open

A

low voltage difference; Na+ ions start depolarization of membrane (enter neuron)

130
Q

what channels open and repolarize the membrane

A

delayed K+ channels; they open in response to membrane depolarization (they are voltage-gated & let K+ move out of cell)

131
Q

When passing through its channel, what ion loses bound water molecules

A

K+ channels (its selectivity filter is composed of oxygens that strip the bound water from K+)

132
Q

what gives rise to a traveling action potential

A

changes in Na+ channels, K+ channels, and current flows

133
Q

what is propagation

A

the action potential travelling down axon

134
Q

what is absolute refractory period

A

includes depolarizing phase (and peak), beginning of repolarizing phase

135
Q

what is relative refractory period

A

hyperpolarizing phase (undershoot)

136
Q

What is the hyperpolarizing phase

A

membrane potential is more negative than resting potential (delayed K+ channels are still open, Na+ already closed)

137
Q

are ion channels open or closed at resting membrane potential

A

Na+ and K+ channels are closed

138
Q

what is absolute refractory period caused by

A

Na+ channel inactivation (depolarizing -> repolarizing)

139
Q

when does electrical signal going down axon stop

A

when it reaches the synapse (end of axon terminals, beginning of target cell)

140
Q

when are receptors on target cell exposed

A

when they receive signal (depolarization) they are brought to surface/synapse

141
Q

chemical vs electrical synapses

A

Chemical: NT release & receptor binding, synaptic cleft, common
Electrical: gap junctions (ions diffuse), no NTs, faster (works as one cell)

142
Q

what is a Neurotransmitter

A

small signal molecule secreted by the presynaptic nerve cell at a chemical synapse to relay the signal to the postsynaptic cell

143
Q

examples of neurotransmitters

A

ACh, Norepinephrine, dopamine, GABA, serotonin…

144
Q

what happens when an AP arrives at presynaptic site

A

depolarization of membrane opens Ca2+ channels on presynaptic membrane, Ca2+ influx triggers NT release into cleft (by exocytosis), NT diffuses across cleft & provokes electrical change in postsynaptic cell by binding to and opening ligand-gated ion channels.

145
Q

Fluorescent Ca2+ sensors are used for what

A

measure increases in intracellular Ca2+ in neurons as a sign of neuronal activity (if neuron is firing, intracellular Ca2+ is high)

146
Q

what is neuromuscular junction

A

specialized chemical synapse between motor neuron & muscle cell

147
Q

what NT is used from motor neuron to muscle cell

A

ACh

148
Q

what is acetylcholine receptor

A

ligand-gated ion channel that opens by acetylcholine released from motoneuron (causing depolarization in muscle cell membrane)

149
Q

what is triggered when incoming AP activates a Ca2+ channel in T-tubule membrane (muscle cell)

A

it triggers the opening of Ca2+-release channel in sarcoplasmic reticulum membrane (it stores Ca2+, releases when depolarized)

150
Q

what is optogenetics

A

biological technique to control the activity of neurons with light (achieved by expression of light-sensitive ion channels in neurons)

151
Q

example of photosensitive ion channel

A

Rhodopsins

152
Q

when do photosensitive ion channels open

A

open in response to light (specific wavelength of light stimulates neuron)

153
Q

what are second messengers

A

intracellular signaling molecules released by cell in response to exposure to extracellular signaling molecules (first messengers)

154
Q

are intracellular molecules soluble

A

yes, can go through nuclear envelope

155
Q

hormones vs local mediators

A

hormones are used for signaling to a far away target cell (endocrine)
local mediators signal to cells in contact, close by, or itself (juxtacrine, paracrine, autocrine)

156
Q

what are 4 different types of receptors

A
  1. ligand-gated ion channel
  2. G protein-coupled receptor (GPCR) (cAMP & Ip3 are second messengers)
  3. Enzyme-coupled receptor (ex: receptor tyrosine kinase)
  4. Nuclear receptor (ex: receptor in cytoplasm brings in lipid)
157
Q

GPCR have how many transmembrane passes

A

7

158
Q

how do GPCRs work

A

hydrolysis of GTP; G protein binds to transmembrane GPCR receptor, receives GTP & becomes activated, leaves and binds/activates enzyme (hydrolysis of GTP inactivates enzyme/G protein)

159
Q

how does signal get across membrane with GPCR

A

GPCR molecules bind to their ligands, then transmit signal across membrane to heterotrimeric G proteins

160
Q

specifics of G protein activation (in GPCR)

A

GPCR is activated when ligand binds; when activated, G protein binds & is activated

161
Q

how long are G proteins active for

A

short period of time

162
Q

What happens when G protein is activated

A

activated G protein triggers cascade of signals inside cell

163
Q

what subunits make up G protein

A

alpha, beta, and gamma (beta and gamma don’t separate)

164
Q

Steps of G protein activation

A

ligand binds to GPCR, G protein binds to GPCR (G-alpha releases GDP & gets GTP), G-alpha (takes GTP) separates from G-beta & -gamma, G-alpha binds to target protein (initiating signal transduction) & G-b&g binds to another protein, G-alpha hydrolyzes its GTP to GDP (becomes inactive), subunits recombine to form inactive G protein

165
Q

how does G protein stay attached to inside of membrane

A

anchored by lipid tail

166
Q

what do some G proteins activate

A

Adenylyl cyclase (is sometimes a target protein)

167
Q

what does adenylyl cyclase make

A

cAMP (converted from ATP to cAMP)

168
Q

what G protein subunit binds to adenylyl cyclase

A

G-alpha

169
Q

What does cAMP act as

A

second messenger of some G proteins

170
Q

what does cAMP activate

A

PKA (protein kinase A), a cAMP-dependent protein kinase (phosphorylate to activate/inactivate pathway)

171
Q

what is the part of PKA that phosphorylates things

A

catalytic subunit phosphorylates things when active

172
Q

what happens when cAMP binds to PKA

A

it binds to regulatory subunit, conformational change happens so catalytic site is available to phosphorylate

173
Q

What do GPCRs use as second messengers

A

cAMP & IP3

173
Q

G protein activates ?

A

phospholipase C (PLC)

174
Q

What does PLC do

A

cleaves PIP2 into DAG & IP3

175
Q

what happens to PIP2 when it is cleaved

A

it becomes DAG (stays anchored to PM) & IP3 (soluble 2nd messenger)

176
Q

What does IP3 bind to/activate

A

IP3 binds to Ca2+ channel at the ER membrane & activates it

177
Q

Ex of Enzyme-coupled receptors/Protein kinase receptors

A

insulin receptor; insulin binds to ligand-gated receptor in dimer form & phosphorylates/activates catalytic domain of receptor

178
Q

structure of enzyme-coupled receptors/protein kinase receptors

A

EGF-binding site (epidermal growth factor receptor) outside PM, 1 transmembrane pass thru PM, tyrosine kinase (in cytosol), cytosolic tail

179
Q

activation of Enzyme-coupled receptor/protein kinase receptor

A

when ligand is bound (extracellular), 2 receptors next to each other will fold their Tyrosine cytosolic tail onto the other, phosphorylating each other

180
Q

what conformational change happens when Enzyme-coupled receptor/protein kinase receptor is activated

A

conformational change exposing kinases (unfolded = catalytic domain exposed = active)

181
Q

example of tyrosine kinase receptor

A

insulin receptor (has binding pocket extracellular, 1 pass through PM, and tyrosine kinase inside

182
Q

what is a steroid hormone

A

steroid that acts as a hormone; they are lipids, soluble/no receptor needed to pass PM or nuclear envelope (have many rings)

183
Q

T or F: nuclear receptors often directly interact with DNA

A

True

184
Q

domains/regions of receptor sequence

A

N-terminal domain, DNA binding domain, hinge region (flexible), ligand binding domain, C-terminal domain

185
Q

example of nuclear receptor

A

molting hormone receptor

186
Q

what is ecdysone

A

steroid hormone that controls insect molting

187
Q

phases of cell cycle

A

G1 (synthesis of proteins, ribosomes, machinery), S (DNA replicated), G2 (gap phase), M phase (mitosis & cytokinesis)

188
Q

what are the phases of mitosis

A

prophase, prometaphase, metaphase, anaphase, telophase (PPMAT)

189
Q

what is everything in cell cycle called that is not mitosis

A

interphase

190
Q

when do chromosomes get duplicated (in cell cycle)

A

S phase

191
Q

mitosis vs cytokinesis

A

mitosis: nuclear division
cytokinesis: cell division

192
Q

Important proteins in cell cycle

A

Cdk & cyclins

193
Q

what has yeast and temperature taught us

A

high temps are restrictive (cells stay in G1 phase), low temps permit cell cycle

194
Q

what happens to cdc mutant cells (in cell cycle)

A

arrest before cytokinesis (need proteins to transition from one stage of cell cycle to another)

195
Q

what happens to cdc2 mutant cells

A

they grow longer and longer, don’t know when to start dividing (mitosis)

196
Q

what is cell-cycle control system based on

A

cyclically activated protein kinases (ex cyclin-dependent kinase = Cdk)

197
Q

when cyclin forms a complex with Cdk, what happens

A

protein kinase is activated (ATP binds to Cdk) to trigger specific cell-cycle event (without binding of cyclin, Cdk is inactive)

198
Q

what do kinases do

A

phosphorylate proteins

199
Q

how is Cdk activity terminated

A

cyclin degradation

200
Q

M-Cdk vs S-Cdk

A

M-Cdk: Cdk + M-cyclin bind to trigger mitosis machinery
S-Cdk: Cdk + S-cyclin bind to trigger DNA replication machinery

201
Q

what 3 cyclin classes are required in eukaryotic cells

A
  1. G1/S-Cdk (activate Cdks at end of G1 & commit cell to DNA replication)
  2. S-Cdk: activate Cdks during S phase & are required for initiation of DNA replication)
  3. M-Cdk: promote events of mitosis
202
Q

what is a fourth common cyclin? Name the 3 main

A

4th = G1-cyclin / G1-Cdk
Main:
G1/S-cyclin, S-cyclin, M-cyclin

203
Q

True or false: each cyclin-Cdk complex phosphorylates a different set of substrate proteins

A

true; cyclins confer specificity to the Cdk/cyclin complex

204
Q

what adds another layer of control to Cdk/cyclin complexes

A

Phosphorylation

205
Q

Wee1 kinase vs Cdc25 phosphatase (don’t need to memorize names)

A

Wee mutant: speeds up G2 –> M phase (frequent mitosis)
Cdc25 mutant: inhibits G2–>M phase (cells grow long)

206
Q

what are the final stages of cell division triggered by

A

protein degradation

207
Q

what promotes protein degradation (end of cell division)

A

Anaphase promoting complex (APC); promotes degradation of M-cyclin, promotes anaphase, activated at end of metaphase

208
Q

how does active APC know to degrade M-cyclin

A

M-cyclin is tagged for degradation with polyubiquitin chain

209
Q

what is the main problem in M phase

A

accurately separating & segregating its chromosomes

210
Q

centrosomes in G1 vs G2

A

G1: cell has 1 centrosome
G2: cell has 2 centrosomes

211
Q

where is APC needed

A

transition from metaphase to anaphase

212
Q

Chromosomes before S phase vs after

A

before: 1 chromosome, 1 centromere
after replication: 2 sister chromatids, 1 centromere (holds sister chromatids together)

213
Q

what holds siter chromatids together before chromosome replication

A

cohesin (encircles un-replicated chromosomes as they become sister chromatids

214
Q

what happens at prophase

A

replicated chromosome condense, mitotic spindle assembles outside nucleus (from centrosomes)

215
Q

what happens in prometaphase

A

nuclear envelope breaks, microtubules attach to chromosomes at kinetochore (connection between chromosome & microtubule from centrosome)

216
Q

what end of kinetochore microtubules are attached to sister chromatid pairs

A

Plus end

217
Q

what happens in metaphase

A

chromosomes align to center of spindle (centrosomes head towards poles)

218
Q

what composes mitotic spindle

A

astral and kinetochore microtubules
Astral: short microtubules, may attach to each other but not chromosomes
Kinetochore: microtubules from centrosome that attach to kinetochore on chromosomes

219
Q

What do motor proteins do in mitosis

A

prevent attached astral microtubules from falling off

220
Q

Roles of Kinesin-5, Kinesin-14, Kinesin-4/10

A

Kinesin-5: slide microtubules oriented in opposite directions
Kinesin-14: crosslink antiparallel microtubules at center & moves one of them
Kinesin-4/10: plus directed & push chromosome to center

221
Q

what happens at anaphse

A

sister chromatids separate into 2 chromosomes (shortening of kinetochore microtubules bring chromosomes to poles)

222
Q

what is Aurora B (mitosis)

A

a kinase force sensor that tells cell chromosomes are oriented properly
Low tension = active Aurora B kinase = phosphorylates thing to prevent chromosome separation
High tension = inactive Aurora B kinase = cell ready to transition into anaphase

223
Q

How does Aurora B prevent transition to anaphase

A

when there is low tension, Aurora-B kinase phosphorylates Ndc80 complex, which discourages binding of microtubule to kinetochore

224
Q

what is the cysteine protease responsible for triggering anaphase by hydrolyzing cohesin

A

Separase

225
Q

what happens during telophase

A

chromosomes arrive to poles, new nuclear envelope assembles, contractile ring made & starts contracting; mitosis ends & telophase starts

226
Q

what happens during cytokinesis

A

separates 2 cells using contractile ring (made of actin & myosin) = cleavage furrow, complete nuclear envelope surrounds decondensing chromosomes

Cell Bio (final)- test 1 +new (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions