Quiz 1 Flashcards Preview

Biochem 2 > Quiz 1 > Flashcards

Flashcards in Quiz 1 Deck (255):
1

What gene when mutated causes cystic fibrosis

CFTR gene

2

What does the CFTR gene code for

chlorine transporter

3

Within the cell, what does the chlorine transporter do

transports Cl- from inside the cell to the outside

4

What does the ENaC gene code for

a sodium channel

5

What does the sodium channel do

allow the transport for Na from outside to the inside

6

What happens if the ENaC gene is mutated but the CFTR is working

There is excess hydration of the lung tissue

7

What happens when the CFTR gene is mutated but the ENaC gene is not

there is a large influx of sodium resulting in volume depletion

8

What is passive transport

transport that does not use ATP energy

9

What types of passive transport are there

facillitated diffusion
simple diffusion
ionophore mediated
ion channel

10

What is facilitated diffusion

a substrate moves down its electrochemical gradient via a channel

11

What is simple diffusion

nonpolor compounds are drawn down their concentration gradient across the membrane

12

Does simple diffusion use a channel

no

13

What is ionophore mediated

ion is transported down its electrochemical gradient by binding to a protein that transports it across

14

What is ion channel

ions move down electrochemical gradient through the channel

15

What can occur to the channel in regards to struture

can be ligand gated or ion gated

16

Before equilibrium what is the net flux of ions

large flux from high to low gradients, low flux from low to high gradients

17

At equilibrium, what is the net flux of ions

no net flux

18

Before equilibrium is reached, what is the Vm for ions

greater than zero

19

Why is the Vm greater than zero

large flow of negative ions toward positive and large flow of positive to negative, small flow of positive to positive and negative to negative

20

At equilibrium what is Vm

zero

21

How does a channel/ transporter effect activation energy

lowers the delta G for transport

22

How does the activation, free energy differ between simple diffusion to diffusion with a transporter

simple diffusion has a greater free energy whereas the diffusion with a transporter has a lower energy

23

Why is simple diffusion a higher free energy

amount of energy to strip hydration of molecule, energy to move through hydrophobic membrane and then the energy need to rehydrate

24

Why is diffusion with a transporter lower in free energy

easier to strip molecule, easily moves through the channel that matches its charges and easy rehydration

25

What type of protein is the glucose transporter

integral protein

26

How mmany hydrophobic sections does the glucose transporter have

12

27

What do the 12 hydrophobic sections code for

12 transmembrane segments

28

How many conformations does the glucose transporter have

2

29

What are the two confomations for the glucose transporter

T1
T2

30

In the transmembrane alpha helices, where do the charged and polar amino acids reside

in the interior of the alpha helice

31

Where do the hydrophobic amino acids reside in the transmembrane helices

on the exterior

32

What is the T1 conformation

the channel when it is open to the exterior and allows glucose to bind to the channel

33

What is the T2 conformation

when the channel opens to the inside once glucose binds and allows its release

34

WHat does transportation have

enzyme-like properties

35

What is Kt equivalent to

Km

36

What is Kt

1/2 max velocity of glucose entry

37

In the burk. plot, what is the crossing of the y axis stand for

1/vmax

38

On the burk plot, what does the interception on x axis code for

-1/Kt

39

What is the y axis on the burk plot

1/V0

40

What is the x axis on the burk plot

1/ [S]out

41

what is an epimer

differs at 1 carbon on carbons

42

How do D and L glucose differ

on the 6th carbon one is up or down

43

How does the change on the 6th carbon affect GLUT1

changes the rate.

44

What does the chloride bicarbonate exchanger allow for

antiport exchange of Cl- for HCO3-

45

In respiring tissues what direction does Cl- and HCO3- flow

Cl- transported in
HCO3- transported out

46

In lungs, which direction does Cl- flow and HCO3- flow

Cl- flows out
HCO3- flows in

47

In respiring tissues what direction does CO2 flow

CO2 uptake

48

In lungs what direction does CO2 flow

CO2 released

49

What direction does the bicarbonate formula flow in respiring tissues

CO2+ H2O --> HCO3- +H (allows Cl- in)

50

WHat direction does the bicarbonate formula flow in lungs

HCO3-+ H--> H2O+ CO2

51

What enzyme allows the bicarbonate reaction to move forward or backward

carbonic anhydrase

52

What does active transport require

energy

53

Why does active transport require energy

moving substrates against gradient

54

What types of active transport are there

primary and secondary

55

What is primary transport

movement of one substrate against its electrochemical gradient

56

What is secondary transport

moves two items against substrates electrochemical gradient, driven by ion moving down its gradient

57

What is uniport transport

moving 1 substrate

58

What is cotransport

moving two substrates

59

What is symport

when two substrates move through 1 channel in same direction

60

What is antiport

when two substrates move through 1 channel in opposite directions

61

What are energetic costs

change in substrate to the product

62

How is the energetic costs calculated

deltaG= (8.315J/K*mol)(298K) ln (P/S)= J/mol

63

What is the function of ATPases

to create a gradient

64

WHat is the mechanism of the Na+K+ATPase

pump out 3 Na+ and pump 2 K+ in
creates a -50 to -70mV gradient

65

How much of resting energy is used for the Na+K+ATPase pump

25%

66

What type of protein is the ATPase

integral protein

67

What components make up the P-type ATPase

T,S membrane domains
A, P, N domains

68

What is the first step of P-type ATPase

calcium and ATP bind allowing N domain to move

69

After calcium and ATP bind and N domain moves what occurs

ADP phosphorylates an ASP in P domain

70

After ASP is phosphorylated what occurs

conformational change occurs causing calcium to be released to the lumen

71

What occurs after calcium is released

The A domain moves causing ADP to be released

72

After ADP is released what occurs

P domains becomes dephosphorylated

73

What happens after the P domain becomes dephosphorylated

the A domain resets

74

What happens after the A domain resets

P,T, and S domains reset to E1 conformation

75

What are two inhibitors of Na+K+ATPase

oubain
palytoxin

76

How does ouabain inhibit

locs ATPase open and prevents a conformational change

77

How does palytoxin inhibit

locks ATPase into an open channel

78

What are aquaporins

channels that permit water to cross membrane

79

What type of flow does aquaporins have

a constant flow

80

How many genes for aquaporins have in plants

38 genes

81

Why must H3O+ be kept out of aquaporins

H+ would destroy electrochemical potentials

82

What is an ionophore for K+

valinomyocin

83

Molecules within the aquaporin that help water flow through are what

Asn
His
Arg

84

What types of signals do cells receive constant input from

pH, osmotic strength, availability of food, oxygen, light, presence of noxious chemicals, predators, competitors of food

85

What do the signals that the cells receive elicit

appropriate responses

86

What are appropriate responses

moving towards or away from a cell

87

What is a signal

information that is detected by specific receptors and converted to a cellular response

88

What type of process is the response of a cell

chemical process

89

What is signal transduction

conversion of info into a chemical change

90

What is specificity

precise molecular complementary between the signal and receptor molecules

91

What mediates specificity

weak, non covalent forces

92

In multicellular organisms what else contributes to specificity

only certain cell types have certain receptors

93

What helps achieve sensitivity

high affinity
cooperativity
amplification

94

What helps aid high affinity

receptors have a high affinity for signal molecules, affinity is between ligand and the receptor

95

How is the affinity for the ligand and receptor expressed

Kd

96

What is Kd

dissociation constant

97

What helps aid cooperation

ligand receptor interaction, large changes occur in receptor activation with only small changes in ligand concentration

98

What is amplification

where a signal is amplified by an enzyme cascade

99

What is an enzyme cascade

the ligand binds to a receptor, activates an enzyme that is associated with the receptor, that enzyme activates multiple molecules of a second enzyme which also activates many molecules of another enzyme

100

How fast can an enzyme cascade produce a magnitude

milliseconds

101

Why must signals be terminated

so downstream effects are in proportion to strength of the original stimulus

102

What is modularity

interacting signaling proteins allow a cell to mix and match a set of signaling molecules to create complexes with different functions

103

What are scaffold proteins

proteins that have an affinity for several enzymes that interact in cascades and bring those proteins together

104

What do scaffold proteins ensure

interactions between proteins and enzymes occur at the right time and location

105

What is densitization

when a signal is constantly present the receptor system is desensitized

106

What occurs when the stimulus falls below threshold

the system becomes sensitized again

107

What is integration

the ability of a system to receive multiple signals and produce a unified response

108

What does integration allow

conversing to occur at several levels

109

What does integraiton help maintain

homeostasis

110

What are the 6 basic receptor types

g protein coupled
receptor tyrosine kinase
receptor guanyly cyclase
gated ion channels
adhesion receptors
nuclear receptors

111

What does GPCR stand for

Gprotein coupled receptors

112

What 3 components make up the G protein pathway

G-protein complex, transmembrane receptor, effector enzyme

113

What is the structure of the transmembrane receptor

binding site for ligand, 7 transmembrane helical segments

114

What occurs to the G protein to make it active vs inactive

The GDP gets swapped out for GTP to become active

115

Where is the effector enzyme located

within the membrane

116

What does the enzyme produce

the second messenger

117

What does the second messenger do

affects downstream targets

118

The human genome encodes how many GPCRs

350

119

What are orphan receptors

receptors that do not have their natural ligands identified

120

What do adrenergic receptors bind

epinephrine

121

What is epinephrine

fight or flight hormone, binds to the receptor in the membrane

122

What are the 4 types of adrenergic receptors

alpha1
alpha2
beta 1
beta 2

123

What defines the differences in the adrenergic receptors

their affinities and responses, location within different tissues

124

What is an agonist

structured analogs that bind to the receptor and result in a similar effect to the natural ligand

125

What is an antagonist

analogs that bind without triggering the normal effect and block agonists and natural ligands

126

Where are beta adrenergic receptors found

muscle, liver, adipose tissue

127

What do beta adrenergic receptors do

mediate changes in fuel metabolism and increase the breakdown of glycogen and fats

128

What is the structure of a beta adrenergic receptor

integral protein, 7 transmembrane helices of 20 to 28 AA

129

What is an alternative name for receptors with 7 transmembrane helices

heptahelical receptors

130

What does the binding of epinephrine to the receptor result in

a conformation change

131

Where does the conformational change occur

to the intracellular domain

132

What does the conformational change to the intracellular domain result in

promotes dissociation of GDP and binding of GTP

133

What occurs to the g protein subunit

it separates into complexes

134

What two complexes

beta gamma and then alpha

135

Which complex moves away to activate the next step

the GalphaS

136

What does the GalphaS complex activated

adenyly clyclase

137

What is adenyly cyclase catalize

cAMP

138

What is cAMP catalyzed from

ATP

139

What does cAMP do

activates protein kinase A

140

What does protein kinase A do

regulates downstream effects

141

G proteins that are composed of three parts are what

trimeric

142

What is the stimulatory protein for the G protein complex

alpha subunit

143

What is the structure of adenyly cyclase

integral protein of plasma membrane

144

How does GalphaS attach to the membrane

via covalently attached palmitoyl groups

145

What inactivates the G alpha unity

intrinsic GTPase

146

What does intrinsic GTPase do

self limits

147

What does Protein Kinase A do

phosphorylate Ser or Thr residues of target proteins

148

In its inactive state, what does protein kinase A structure

two catalytic subunitys and two regulatory subunits

149

When bound together, what is the strucure of PKA like

auto inhibitory domain of each subunit occupies the substrate binding cleft of catalytic domains

150

when cAMP binds to PKA R subunitys, what occurs

R moves out of catalytic domain and dissociates R and C subunits

151

What is a consensus sequence

neighboring residues needed to make Ser or Thr residue for phosphorylation

152

What are the 3 mechanisms that cause G protein termination

concentration of epinephrine
hydrolysis of GTP bound to G alpha subunit
remove 2nd messenger

153

How does the concentration of epinephrine lead to termination of G protein complex

when epinephrine drops belows Kd, the hormone dissociates from the receptor and resumes inactive conformation

154

How does inactivation through hydrolysis of GTP bound to G alpha subunit occur

GTPase activity occurs and GTP becomes GDP

155

How does removing the 2nd messenger inactivate complex

hydrolysis of cAMP to 5'AMP

156

What causes the hydrolysis of cAMP to 5'AMP

cyclic nucleotide phosphodiesterase

157

What does desensitization cause

dampening the response even when the signal persists

158

What mediates densitization

protein kinase that phosphorylates receptor on intracellular domain

159

What does Beta ARK do

phosphorylate Ser residues

160

What does BARK function

creates a binding site for Beta arrestin

161

What does beta arrestin do

prevents further interaction of receptor and G-protein
facilitates receptor sequestration removal of receptors from membranes into vesicles

162

Can PKA move into the nucleus

yes

163

When PKA moves into the nucleus what does it do

phosphorylates CREb

164

What are adaptor proteins

proteins that hold together other protein molecules

165

What is the receptor tyrosine kinase family

large family of plasma membrane receptors with intrinsinc protein kinase activity

166

How do tyrosin kinase family receptors transduce extracellular signals

via the ligand binding domain and enzyme

167

Where is the ligand binding domain on the receptor

on extracellular side

168

Where is the enzyme domain on the receptor

intracellular side

169

How are the ligand binding domain and enzyme connected

by a single transmembrane segment

170

What is the enzyme of the tyrosine kinase family do

phosphorylate Tyr residues in specific target proteins

171

What is the type of enzyme in tyrosine kinase family

tyrosine kinase

172

What is the function of insulin

regulates metabolic enzymes and gene expression

173

Does insulin enter the cells

no

174

What does insulin do to change gene expression

initiates a signal that travels a branched pathway from PM to insulin sensitive enzymes in cytosol and nucleus

175

The units that make up the extracellular receptor are what

identical alpha subunits

176

What are the units that make up the intracellular receptor

identical beta subunits

177

the tyrosine receptor is made up of what

two alpha/beta monomers to make a dimer

178

which subunit has insulin binding domain

alpha

179

which subunit has kinase activity

beta

180

What does the tyrosine kinase do

transfers phosphate from ATP to hydroxyl group of tyrosine residues

181

each beta subunit phosphorylates what

3 tyrosine residues in beta subunit

182

What type of phosphorylation is this

autophosphorylation

183

What does autophosphorylation cause

opens up the active site so the enzyme can phosphorylate tyrosine residues of other target proteins

184

In the insulin what occurs first

autophosphorylation of INSR occurs

185

What is the target of INSR

insulin receptor substrate 1

186

What does INSR do to INRS-1

phosphorylates on several tyrosine residues

187

What occurs to the activated IRS1 molecule

becomes point of nucleation for complex of proteins that carry message from insulin receptor to targets in cytosol and nucleus

188

What does the phosphorylate tyrosine domain of IRS1 bind

SH2 domain of Grb2 protein

189

What is Grb2 protein

an adaptor protein

190

What does Grb2 protein have

SH3 domain

191

What does the SH3 domain bind

proline rich SOS that acts as guanosine nucleotide exchange factor

192

What does the guanosine nucleotide exchange factor do

replace bound GDP with GTP on Ras, a G-protein

193

What is Ras

a small family of G-proteins

194

What does Ras do

activates Raf-1

195

What is Raf-1

protein kinase

196

What does Raf1 do

activates MEK

197

What does MEK do

activates ERK

198

How are MEK and ERK activated

phosphorylation of both threonine and tyrosine residues

199

What does ERK do

enters nucleus and phosphorylates transcription factors

200

What does ERK phosphorylate

Elk1

201

What does Elk1 do

modulates 100 insulin regulated genes

202

What does insulin act as

growth factor

203

What family does ERK belong to

MAPK

204

What does MAPK stand for

mitogen activated protein kinase

205

What is mitogen

extracellular signals that induce mitosis and cell division

206

What family does MEK belong to

MAPKK

207

What family does Raf1 belong to

MAPKKK

208

What do MAPK, MAPKK, MAPKKK make up

the MAPK cascade

209

What functions as a branch in the insulin signaling pathway

PIP3 pathway

210

Where does the PIP3 pathway branch in the insulin signaling pathway

where the insulin receptor substrate 1 is phosphorylated

211

What interacts with IRS1 through its SH2 domain

PI3K

212

What does PI3K do

convert PIP2 to PIP3

213

What does the charged phosphorylated head protrude into

the cytoplasmic side

214

What attaches to PIP3

protein kinase B

215

What occurs to PKB when attached to PIP3

phosphorylated by PDK1

216

What occurs once PKB is phosphorylated

it phosphorylates Serine and threonine residues of glycogen synthase kinase 3

217

when phosphorylated by PKB is glycogen synthase kinase3 inactive or active

inactive

218

What does PKB trigger

clathrin aided movement of glucose transports from internal vesicles to PM

219

What terminates PI3K activity

PIP3 specific phosphatase

220

What type of kinase activity does the JAK STAT signaling system involve

tyrosine

221

In the JAK STAT signaling system, is there always kianse activity

no

222

When is there JAK STAT signaling system when is there kinase activity

when the ligand binds

223

When the ligand binds, what binds to give the receptor kinase activity

tyrosine kinase

224

Whay is a cytokine for JAK STAT system

erythropoeitin

225

Where is erythropoeitin produced

in kidneys

226

When the tyrosine kinase binds what occurs to the receptor

receptor dimerizes and activates JA kinase

227

What is the function of the JA kinase

phosphorylates Tyr residues in cytoplamic domains of EPO receptor

228

What are STATs

collection of transcription factors that are targets of JAK

229

STATs bind what

phosphorylate tyroside residues in EPO receptor

230

phosphorylates STATS move where

into the nucleus

231

What do phosphoylated STATs moving into the nucleus result in

transcription of specific genes

232

What can JAK also trigger

MAPK cascade

233

What are the general features of a receptor protein of enzyme

ligand binding domain or active site
transmembrane segment

234

Under what conditions is insulin released

when blood glucose levels are high

235

What does signal transduction mean

converting information into a chemical signal to result in cellular responses

236

What is a hormone

a small chemcial molecule produced by various tissue types that bind to receptor to stimulate cell response. Hormones are produced by one cell and act upon another

237

What is the end product of most signals

phosphorylation for enzyme activation and inhibition

238

How do gated ion channels work

open or close in response to concentrations of signal ligand

239

How do receptor enzymes work

ligand binding to extracellular domain stimulates enzyme activity in intracellular domain

240

How do serpentine receptors work

external ligand binding to receptor activates GTP binding protein which regulates an enzyme

241

What is receptor with no intrinsic enzymatic activity work

interacts with cytosolic protien kinase which activates a gene regulating protein to change gene expression

242

How do adhesion receptors work

binds molecules in extracellular matrix and changes conformation thus altering its interaction with cytoskeleton

243

How do steroid receptors work

steroid binding to a nuclear receptor protein allows the receptor to regulate the expression of specific genes

244

What does a smaller Kd mean

has greater affinity for ligand and receptor

245

How is glycogen phosphorylase b activated by epinephrine

epinephrine binds
activates G protein
activates adenyly cyclase to produce cAMP
cAMP activates protein kinase A
PKA phosphorylates phosphorylase b
phosphoylase b phosphoylates glycogen phosphorylase b to become active

246

How is PKA regulated by cAMP

allosterically by binding at a site other than active site

247

WHat enzyme is responsible for the degradation of cAMP

cyclic nucleotide phosphodiesterase

248

What does cAMP become

5'AMP

249

What allows beta arrestin to bind

after Barr phosphorylates Serine residues of the carboxyl terminus of the receptor

250

When arrestin is bound to the receptor what occurs

the receptor enters cell via endocytosis

251

In the inactive state of the insulin receptor what is its arrangement and structure

an unphosphorylated tyrosine domain keeps the activation loop in a position that blocks substrate binding site

252

In active state what is structure of receptor

the negative aspartate groups nearby the phosphorylate tyrosine cause conformational change that moves the activation loop to move making room for target protein in substrate to bind

253

What is the signaling pathway for insulin

insulin binds to receptor
receptor undergoes autophosphorylation
receptor phosphorylates IRS-1 on Tyr residues
SH2 domain of Grb2 binds to IRS1, SOS binds to Grb2 and then to Ras
causes GDp release and GTP binding to Ras
Ras binds to Raf1/activates it
Raf1 phosphorylates MEK on serine residues
MEK phosphoryles ERK on threonine residues
ERK moves into nucleus
ERK phosphorylates Elk1
Elk1 joins SRF to stimulate the transcription of genes

254

What is the signaling pathway for glycogen synthesis

IRS1 activates PI3K (binds to SH2 domain)
PI3K converts PIP2 to PIP3
PKB bound to PIP3 is phosphorylated by PDK1
PKB inactivates GSK3
GSK3 cannot convert glycogen synthase to inactive form
synthesis of glycogen is accelerated
PKB stimulates movement of glucose transporter to PM

255

What is PIPs

cell membrane lipids