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OLD "MBS 602" > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

Biological membranes are __layers

A

bilayers

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2
Q

What are biological membranes made of?

A

lipids and proteins
(sometimes glycolipids/glycoproteins)

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3
Q

What are 3 important properties of biological membranes?

A
  1. fluid (lipid/protein migration occurs)
  2. mosaic (not uniform)
  3. asymmetric (two layers are not the same)
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4
Q

Why are membranes arranged into a bilayer?

A

their lipids are amphipathic

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5
Q

What are the 4 types of membrane lipids?

A
  1. phospholipids
  2. glycolipids
  3. sterols
  4. ether lipids
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6
Q

What are the possible backbones of phospholipids?

A

glycerol or sphingosine
(glycero-phospholipids or shingo-phospholipids)

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7
Q

What are the possible backbones of glycolipids?

A

glycerol or sphingosine

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8
Q

Do humans have ether membrane lipids?

A

no (archaebacteria)

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9
Q

How many carbons is a glycerol backbone?

A

3

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10
Q

How many carbons is a sphingosine backbone?

A

18

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11
Q

How many tails do glycero-phospholipids have?

A

2

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12
Q

How many tails do sphino-phospholipids have?

A

1

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13
Q

What determines the function of a phospholipids?

A

functional group added to the head of lipid

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14
Q

Some glycero-phospholipids have _____ linkage at C1 position of glycerol

A

ether

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15
Q

On glycero-glycolipids, the C3 is linked to _________ instead of a phosphate group (like phospholipids)

A

galactose

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16
Q

What kind of membrane lipid is most common especially in plants?

A

glycero-glycolipids

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17
Q

What glycolipids is abundant in the brain and nerve tissue?

A

sphingo-glycolipids

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18
Q

What membrane lipid is a derivates of ceramides?

A

sphingo-glycolipids

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19
Q

What do sterols look like?

A

4 fused carbon ring

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20
Q

What is the major sterol in humans?

A

cholesterol

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21
Q

What is special about ether lipids?

A

resistant to high temperatures and extreme pHs

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22
Q

Lipid composition of membranes depends on their __________

A

function

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23
Q

Phophatidycholine and sphingomyelin are mainly in the ______ monolayer

A

outer

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24
Q

Phosphatidyl serine and phosphatidylinositol are mainly in the _______ layer

A

inner

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25
Q

What is a flippase?

A

flips lipids from outer to inner

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26
Q

What is a floppase?

A

flips lipids from inner to outer

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27
Q

What is a scramblase?

A

can flip lipids outer to inner and vise versa

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28
Q

Why don’t lipids flip bilayers often?

A

the polar head has to pass through the non-polar tail region which is no favored

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29
Q

What is a hypotonic environment?

A

(cell swells)
more salt inside the cell so water flows inside the cell

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30
Q

What is a hypertonic environment?

A

(cell shrivels up)
more salt outside the cell so water flows out of cell

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31
Q

At low temperatures, bilayer lipids are ______ forming a gel phase called ______-______ state

A

ordered
solid-ordered state

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32
Q

At high temperatures, bilayer lipids are _______ forming a ________-_______ state

A

moving
liquid-disordered state

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33
Q

Membranes with cholesterol have a 3rd possible state known as _____-_______ state, which is where lipids are moving but ordered

A

liquid-ordered state

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34
Q

Membranes have _______ enriched with specific lipids and proteins

A

microdomains

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35
Q

Membranes that carry out many enzyme-catalyzed reactions and transport activities are richer in __________

A

proteins (ex: mitochondria inner membrane)

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36
Q

What are the 3 types of membrane proteins?

A
  1. integral
  2. peripheral
  3. lipid-anchored
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37
Q

What kind of membrane protein is embedded in the membrane?

A

integral

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38
Q

What kind of membrane protein is transmembrane?

A

integral

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39
Q

What kind of membrane protein cannot be released without denaturing the membrane?

A

integral

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40
Q

What kind of membrane protein is not strongly bound to membrane?

A

peripheral

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41
Q

What kind of membrane protein can be detached with mild detergent and high salt?

A

peripheral

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42
Q

What kind of membrane protein are temporarily anchored?

A

lipid-anchored

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43
Q

What is the hydrophobicity index?

A

value assigned to each amino acid residue to determine hydrophobic to find transmembrane regions of proteins
(higher the number the more hydrophobic)

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44
Q

Do antibiotics target high or low hydrophobicity index regions?

A

low (outside the membrane)

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45
Q

Why are beta sheets used in membrane proteins?

A

don’t require as much genetic material

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46
Q

What kind of interaction bind peripheral proteins to membrane?

A

ionic (can be disrupted by salt)

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47
Q

What kind of interaction bind lipid-anchored proteins to membrane?

A

covalent bonds (not affected by salt)

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48
Q

What are 2 types of lipid-anchored proteins?

A
  1. amide-linked myristol anchors
  2. GPI anchors
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49
Q

Where are amide-linked myristol anchors located?

A

N terminal (beginning)

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50
Q

What are amide-linked myristol anchors always linked to?

A

Gly residue

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51
Q

Where are GPI anchors located?

A

C terminal (end)

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52
Q

What direction do GPI anchor proteins face?

A

outside the cell

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53
Q

Integral membranes proteins with ______ shape can induce curvature

A

conical

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54
Q

What is required for diffusion to occur?

A

concentration difference

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55
Q

Select the correct transport(s)…
goes down the concentration gradient

A

passive
facilitated

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56
Q

Select the correct transport(s)…
requires transport proteins

A

facilitated
active

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57
Q

Select the correct transport(s)…
requires ATP

A

active

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58
Q

Select the correct transport(s)…
transports small non-polar molecules

A

passive

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59
Q

Select the correct transport(s)…
goes up the concentration gradient

A

active

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60
Q

Select the correct transport(s)…
does not require transport proteins

A

passive

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61
Q

Select the correct transport(s)…
does not require ATP

A

pasive

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62
Q

Select the correct transport(s)…
transports large/polar/charged molecules

A

facilitated
active

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63
Q

Select the correct transport…
transports O2 and steroids

A

passive

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64
Q

Select the correct transport(s)…
transports Cl-, Na+, H2O

A

facilitated

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65
Q

Select the correct transport(s)…
glucose, histidine

A

active

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66
Q

How does reaching equilibrium change when the passive diffusion molecule has a charge?

A

the concentrations may be different because of the potential differences

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67
Q

Is the delta G positive or negative for facilitated diffusion?

A

negative (thermodynamically favored)

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68
Q

Why does facilitated diffusion have a hyperbolic curve?

A

its faster at lower [ ]s and levels off at higher [ ]s because the proteins become saturated

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69
Q

What are 5 types of pores/channels?

A
  1. ionophores
  2. porins
  3. ion channels
  4. aquaporins
  5. transporters
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70
Q

What are ionophores used for?

A

used to kill bacteria (not in humans)

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71
Q

____ channels can be opened and closed upon signals

A

ion channels

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72
Q

What are uniports?

A

transport one thing one way

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73
Q

What are symports?

A

transports two things one way

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74
Q

What are antiports?

A

transports 2 things in opposite directions

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75
Q

Potassium channels are highly selective of K+, how?

A

specific highly conserved AA sequence at entrance of channel

76
Q

How many subunits does a potassium channel have?

A

4

77
Q

How is K+ transported through the potassium channel?

A

in a line with H2O between each K+ to prevent repulsion

78
Q

Potassium channel is gated by intracellular ____ meaning _____ is the entrance signal

A

pH
H+ (protons)

79
Q

Potassium channels are open at ______ pH and closed at ______ pH

A

open: low pH
closed: neutral pH

80
Q

What is a primary active transporter?

A

use ATP as an energy source

81
Q

What are examples of secondary active transporters?

A

symporters and antiporters (use electrochemical gradient)

82
Q

What is an example of a primary active transporter?

A

sodium/potassium pump

83
Q

How do Na+/K+ pumps maintain the negative intracellular cellular charge?

A

pumping 3 Na+ out and 2 K+ in (-1 inside)

84
Q

What is the energy source of Na+/K+ pumps?

A

ATP hydrolysis

85
Q

What are the 2 conformations of Na+/K+ pumps?

A

open to inside (E1)
open to outside (E2)

86
Q

Why do Na+/K+ pumps have 2 conformations?

A

prevents ions from freely traveling in and out of cell

87
Q

What are the 4 domains of Na+/K+ pumps?

A

N (nucleotide-binding)
A (actuator)
P (phosphorylation)
T (transport)

88
Q

What domain does K+ bind to in Na+/K+ pumps?

A

T domain

89
Q

What is endocytosis?

A

transport into cell via vesicle

90
Q

What is exocytosis?

A

transport out of cell via vesicle

91
Q

What is CFTRs function?

A

Cl- channel

92
Q

Where is Cl trying to go in cystic fibrosis?

A

out of the cell but it cannot

93
Q

Cystic fibrosis is the impairment of _____ transport

A

Cl-

94
Q

What is juxtacrine signaling?

A

signaling between adjacent cells

95
Q

What is paracrine signaling?

A

short distance signaling (cytokines)

96
Q

What is endocrine signaling?

A

long distance signaling (hormones)

97
Q

What are 2 examples of juxtacrine signaling?

A

gap junctions
membrane-bound ligands

98
Q

What are gap junctions?

A

(juxtacrine signaling) connexins connect 2 cells allowing ions the flow

99
Q

What is signaling by membrane-bound ligands?

A

(juxtacrine signaling) direct contact between cell 1 ligand and cell 2 receptor

100
Q

_________ are signaling molecules that bind specifically to a receptor

A

ligands

101
Q

What is a ligand-gated ion channel?

A

ion channels that open upon binding of ligand (ion)

102
Q

What is an example of a ligand-gated ion channel and what was its ligand?

A

K+ channel (H+ ligand; low pH intracellular environment)

103
Q

Ligand gated ion channel have _____ distinct conformations. Why?

A

2
prevents ions from freely going where ever

104
Q

What is the special 3rd conformation of ligand-gated ion channels?

A

desensitized (won’t open even if ligand binds)

105
Q

Where are nuclear hormone receptors located?

A

in cytosol or nucleus
** inside cell

106
Q

What kind of ligands do nuclear hormone receptors use?

A

non-polar (must get inside of cell easily to get to receptor)

107
Q

What do type I nuclear hormone receptors look like ligand bound and unbound?

A

unbound: monomer
unbound: homodimer

108
Q

What is an example of a type I nuclear hormone receptor?

A

estrogen

109
Q

Estrogen receptor has a ton of functions, how is this possible?

A

uses co-activators and co-repressors for transcription

110
Q

What’s the largest family of cell surface receptors and is a major drug target?

A

GPCR

111
Q

How many domains does GCPR have?

A

7

112
Q

Are GCPR integral proteins?

A

yes

113
Q

In GPCR, binding of ligand to GPCR induces a conformational change that activates ___________

A

G-protein

114
Q

G-alpha protein interact with ______ and binds ______

A

GCPR
GTP/GDP

115
Q

G-alpha+gamma are ________ anchored

A

lipid anchored (need to be able to move near receptor which is integral)

116
Q

G protein is active when ____ is bound and inactive when ____ is bound

A

GTP
GDP

117
Q

What is GAP? (GPCR)

A

increases GTPase activity
(GTP hydrolysis)

118
Q

What is GEF? (GPCR)

A

promotes exchange of GDP to GTP

119
Q

What are the 3 subunits of the G-alpha trimeric protein?

A
  1. Gs
  2. Gi
  3. Gq
120
Q

trimeric Gs protein activates _________ which increases ________

A

adenylyl cyclase
cAMP

121
Q

trimeric Gi protein inhibits _________ which decreases _________

A

adenylyl cyclase
cAMP

122
Q

What makes cAMP?

A

adenylyl cyclase

123
Q

cAMP, Ca2+, IP2 and DAP are examples of?

A

secondary messengers

124
Q

___________ is the main mediator of cAMP signaling

A

protein kinase A
(cAMP–>PKA—>gene effect)

125
Q

Activated Gq trimeric protein activates ___________

A

phospholipase C-B

126
Q

Activated phospholipase C hydrolyzes ______ which yields ______ and _____

A

PIP2
IP3 & DAG

127
Q

What is the fate of DAG once its made from PIP2?

A

stays in membrane and activates protein kinase C

128
Q

What is the fate of IP3 once its made from PIP2?

A

diffuses into cytosol and induces release of Ca2+

129
Q

How is the GPCR signaling termianted?

A

arrestins bind to phosphorylated receptor preventing G protein from binding

130
Q

What happens to GPCR after arrestins bind?

A

receptor is endocytosed and can continue to signal

131
Q

Where is adenylyl cyclase located?

A

membrane

132
Q

NOTCH signaling is a highly ______ pathway

A

conserved

133
Q

What are the ligands for NOTCH?

A

JAG and DLL

134
Q

How many types of NOTCHs are there in mammals?

A

4

135
Q

What is an example of proteolysis regulated receptors?

A

NOTCH

136
Q

Where is notch located?

A

membrane

137
Q

What activates NOTCH receptor?

A

binding of ligand and cleavage

138
Q

Why is NOTCH cleaved?

A

can enter nucleus

139
Q

What is NOTCH important for?

A

cell fate

140
Q

Is notch contact or paracine signaling?

A

contact

141
Q

Are hormones a ligand for NOTCH?

A

no (contact signaling)

142
Q

How many times can you activate NOTCH?

A

once (its cleaved)

143
Q

IP3 causes the release of _____

A

calcium

144
Q

enzyme linked receptors have how many transmembrane domains?

A

1

145
Q

Receptor tyrosine kinase is an example of what kind of receptor?

A

enzyme linked receptor

146
Q

What kind of receptor is receptor-like tyrosine phosphatase?

A

enzyme-linked receptor

147
Q

What is the intracellular part of receptor tyrosine kinase?

A

tyrosine kinase

148
Q

On the receptor tyrosine kinase, binding of the ligand activates ______________ domain

A

tyrosine kinase

149
Q

receptor tyrosine kinase is __________ when inactive and ________ when active

A

monomer
dimer

150
Q

When receptor tyrosine kinase dimerizes what happens?

A

autophosphorylation

151
Q

Phosphorylated tyrosine kinase on RTK acts as a _________ for intracellular signaling proteins

A

docking site

152
Q

proteins that use receptor tyrosine kinase but don’t have SH2 or PTB domains rely on _________ to create a docking site to bind to receptor

A

scaffolding protein

153
Q

What are the 3 possible pathways for receptor tyrosine kinase?

A

1, MAPK
2. PI3K
3. PLC

154
Q

MAPK pathway has _____ kinases in succession

A

3

155
Q

What is the first kinase in the MAPK pathway?

A

Ras (monomeric G protein)

156
Q

How is Ras connected to membrane?

A

lipid anchored

157
Q

Ras is the GEF for monomeric G proteins. What is the GEF for trimeric G proteins?

A

the GPCR

158
Q

What kind of kinase is used in PI3K pathway?

A

lipid kinase

159
Q

In the PLC pathway, _________ is cleaved into ______ and _______

A

PIP2
DAG & IP3

160
Q

What pathway of receptor tyrosine kinase uses G proteins?

A

MAPK (monomeric G protein

161
Q

What does Ras GEF do in receptor tyrosine kinase?

A

exchanges GDP for GTP

162
Q

How does receptor tyrosine kinase use localization in MAPK pathway?

A

moves Ras GEF closer to receptor for activation

163
Q

How is MAPKK a dual specificity kinase?

A

can phosphorylate tyrosine and threonine/serine

164
Q

_____ domain of receptor tyrosine kinase binds specifically to phosphorylated tyrosine residues

A

SH2

165
Q

_____ activates a downstream serine/threonine phosphorylation cascade that includes MAP kinase

A

Ras

166
Q

In the PI3K pathway, PIP3 —-> _____ —–>

A

AKT
mTORC1

167
Q

What does PTEN do in the PI3K pathway?

A

dephosphotylates PIP3 to stop signaling

168
Q

PI3K is a major pathway in cell _____________

A

growth/survival

169
Q

What is made in the PLC-g pathway?

A

IP3 and DAG

170
Q

What is a signaling pathway used by tyrosine kinase associated receptors?

A

JAK/STAT

171
Q

What is STAT?

A

transcription factor

172
Q

How is the JAK/STAT pathway terminated?

A

dephosphorylation of STAT and JAK

173
Q

What is the ligand for receptor-like tyrosine phosphatase?

A

unknown

174
Q

The _____________ domain of receptor serine/threonine kinase is serine and threonine kinase

A

intracellular

175
Q

What is an example of a receptor serine/threonine kinase signaling pathway?

A

TGF-B

176
Q

In TGF-B signaling, ligand first binds to type II receptor then type ____

A

type I

177
Q

Activated receptor serine/threonine kinase in the TGF-B signaling pathway recruits ________

A

Smads

178
Q

What is the secondary messenger for receptor guanylyl cyclase?

A

cGMP

179
Q

The secondary messenger, cGMP, of receptor guanylyl cyclase activates ______ and _______

A

Protein kinase G
cGMP Ca2+ channel

180
Q

Can signaling pathways combine?

A

yes

181
Q

Do some reponses require activation of multiple pathways?

A

yes

182
Q

Steroid hormones, such as cortisol, typically act by entering the cell and binding to receptor or binding on cell surface?

A

entering cell and acting as transcription regulators

183
Q

The endogenous GTPase activity of G-proteins serves to hydrolyze ______, returning the G-protein to a pre-stimulation level of activity

A

GTP

184
Q

What’s the difference between a channel and a transporter?

A

transporters are never full open (they have 2 conformations)
channels are just a hole that opens

185
Q

For receptor tyrosine kinase, proteins that have ____ and ____ domains can bind to tyrosine docking site

A

SH2
PTB

186
Q

Most glycolipids in mammals is derived from _______

A

ceramides

187
Q

Can simple diffusion be saturated?
Can facilitated diffusion?

A

simple: no
facilitated: yes

OLD "MBS 602" (7 decks)

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