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Biochem > Exam 3 Ch 10, 11, 12 > Flashcards

Exam 3 Ch 10, 11, 12 Flashcards

1
Q

What are fatty acids

A

Hydrocarbon derivatives
-carboxylic acids with hydrocarbon tails from 4 to 36 carbons long
-can be saturated or unsaturated, branched or unbranched

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2
Q

Oxidation of fatty acids (to CO2 and H2O) is highly…

A

Exergonic

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3
Q

most common fatty acids have ___ number of C atoms in an _____ chain of __ to __ C’s

A

even
unbranched
12 to 24

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4
Q

in monosaturated fatty acids, the double bond is usually between

A

c9 and c10

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5
Q

in polysaturated fatty acids

A

the double bonds are usually c 12 and c 15
double bonds seperated by a methylene group

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6
Q

double bonds in general in fatty acids

A

in cis config

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7
Q

describe poly unsaturated fatty acids

A

-have more than one double bond in their backbone
-omega 3 have db between c3 and c4 relative to the most distant carbon
-omega 6 have db between c6 and c7

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8
Q

PUFA and human nutrition

A

-humans must obtain omega 3 PUFA a-linolenic acid (ALA) 18:3 from diet
-humans use ALA to make EPA and DHA
-the optimal diet ratio of omega6 to omega3 PUFA is between 1:1 and 4:1

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9
Q

triaclyglycerols

A

simplest lipids made from fatty acids
-made of 3 fatty acids, each in ester linkage with a glycerol
-can be one kind of fatty acid or mixed of 2-3 kinds
-non polar, hydrophobic

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10
Q

solubility of fatty acids

A

poor solubility in water bc of nonpolar HC chain
-increased chain length dec solubility
-dec db number dec solubility

-carboxylic acid group is polar and ionized at neutral pH

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11
Q

melting points of fatty acids

A

at RT: saturated fatty acids are waxy
-unsat fatty acids are oily liquids

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12
Q

triclyglycerols provide…

A

stored energy and insulation against low temp

-vertebrates store triclyglycerols as lipid droplets in fat cells

-plants store triclyglycerols in the seeds

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13
Q

lipases…

A

enzymes that catalyze hydrolysis of stored triclyglycerols, releasing fatty acids for export to sites where theyre required as fuel

-fat cells and germinating seeds contain lipases

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14
Q

advantages of triclyglycerols uses as stored fuels

A

-oxidation of fatty acids yields more energy

-triclyglycerols are hydrophobic and unhydrated, so the organism doesnt have to carry the extra weight of water hydration thats associated with stored polysaccharides

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15
Q

partial hydrogenation

A

process that converts many of the cis db in the fatty acids to single bonds

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16
Q

______________________ to aldehydes and carboxylic acids causes lipid rich food to become rancid

A

oxidative cleavage of db in unsaturated fatty acids

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17
Q

effects of partial hydrogenation

A

-improves shelf life
-increases the melting temp
-converts some cis db to trans db

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18
Q

trans fatty acids

A

dietary intake of trans fatty acids= cardiovasc disease

and:
-level of triaglycerols in the blood
-raise level of LDL- bad cholesterol in the blood
-lower level of HDL- good cholestreol in the blood
-inc body inflammatory response

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19
Q

waxes serve as…

A

energy stores and water repellant

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20
Q

biological waxes

A

esters of long chain saturated and unsat fatty acids with long chain alcohols
-have higher mp than triaglycerols
-firm consistency

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21
Q

features of linoleic acid

A

-two db
-one carbox acid group
-C-C db between carbons 9 and 10

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22
Q

membranes are

A

double layer of lipids that acts as a barrier to polar molecules and ions

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23
Q

membrane lipids

A

-amphipathic (one end is Np, the other polar)
-hydrophobic regions associate w e/o
-hydrophilic regions associate w water

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24
Q

general types of membrane lipids 3

A

-phospholipids- hydrophobic regions with 2 fatty acids joined to glycerol or sphingosene

-glycolipids- contain simple sugar or a complex oligosaccharide at the polar ends

-sterols- rigid system of 4 fused HC rings

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25
Q

glycerophospholipids are derivatives of …

A

phosphodatic acid

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26
Q

glycerophospholipids

A

membrane lipids that have two fatty acids are attached using ester linkage to the 1st and 2nd carbons of glycerol and a highly polar or charged group is attached through phosphodiester linkage to the 3rd carbon

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27
Q

glycerol is…

A

prochiral

-attachment of phosphate at one end of glycerol converts it to a chiral compound

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28
Q

glycerophospholipds are named as…

A

derivatives of phosphodatic acid

-a phosphodiester bond joins the head group to a glycerol
-the phosphate group can bear a negative, neutral, or positive change

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29
Q

the fatty acids in glycerophospholipds

A

-can be wide variety
-in general contain:
c16 or c18 saturated fatty acid at c1
c18 or c20 unsat fatty acid at c2

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30
Q

ether lipids (some glycerophospholipds have ether linked fatty acids)

A

one of the 2 acyl chains is attached to a glycerol in ether linkage rather than ester linkage

-chain may be saturated
-may have a db between c1 and c2 as in plasmalogens

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31
Q

platelet activating factor

A

an ether lipid that serves as a potent molecular signal
-released from basophils
-stimulates platelet aggregation and serotonin release
-plays a role in inflammation

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32
Q

sphingolipids are a derivative of…

A

sphingosine

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33
Q

what are sphingolipids?

A

large class of membrane phospholipids and glycolipids
-they have a polar head group and 2 non polar tails
-no glycerol
-one molecule of long chain amino alcohol sphingosine or one of its derivatives

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34
Q

_________ are the structural parent of all sphingolipids

A

ceramides

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35
Q

what is a ceramide

A

-created when a fatty acid is attached in an amide linkage to the NH2 on the C2
(structure is similar to diaclyglycerol)

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36
Q

__, __, and ___ of sphingosine are structurally analogous of the 3 carbons of glycerol in glycerophospholipids

A

C1 , C2, and C3

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37
Q

sphingomyelins

A

subclass of sphingolipids that have phosphocholine or phosphoethanolamine as their polar head group

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38
Q

glycosphingolipids

A

have head groups with 1+ sugars connected to the OH at C1 of the ceramide moiety
(dont have a phosphate, and they occur in the outer face of plasma membranes)

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39
Q

cerebrosides

A

have single sugar linked to ceramide
no charge at pH 7

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40
Q

cerebrosides with galactose

A

are found in the plasma membrane of cells in neural tissue

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41
Q

cerebrosides with glucose

A

are found in the plasma membrane of cells in non neural tissues

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42
Q

globosides

A

glycosphingolipids with 2+ sugars, usually D glucose, D galactose, or N-acetyl-D-galactosamine

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43
Q

gangliosides

A

oligosaccharides as their polar head group and 1+ residue of N-acetylneuraminic acid (Neu5Ac), a sialic acid, at the termini

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44
Q

gangliosides:
1 sialic acid residue

A

Gm (mono)

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45
Q

gangliosides:
2 sialic acid residue

A

GD (di)

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46
Q

gangliosides:
3 sialic acid residue

A

GT (tri)

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47
Q

sphingolipids at cell surfaces are sites of…

A

recognition.

-they’re prominent in the plasma membranes of neurons
-human blood groups are determined partly by the oligosaccharide head groups of these glycosphingolipids

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48
Q

phospholipids and sphingolipids are _____ in lysosomes

A

degraded.

-phospholipases of the A type remove one of the 2 fatty acids
-lysophospholipases remove the remaining fatty acid
-lysosomal enzymes catalyze the stepwise removal of sugar units of gangliosides

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49
Q

sterols have four….

A

fused carbon rings

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50
Q

what are sterols?

A

structural lipids that are in the membranes of most euk cells

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51
Q

steroid nucleus consists of …

A

-four fused rings
-almost planar
-relatively rigid

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52
Q

explain cholesterol

A

-major sterol in animal tissue
-amphipathic
-polar head group
-NP hydrocarbon body
-membrane constituents
-similar to stigmasterol in plants and ergosterol in fungi

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53
Q

______ hormones regulate gene expression

A

steroid

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54
Q

bile acids

A

polar derivatives of cholesterol that emulsify dietary fats in the intestine to make them more readily accessible to digestive lipases

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55
Q

__________ are a parent compound of sphingolipids

A

ceramides

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56
Q

what are the products of phospholipase D’s degradation of phospphatidylethanolamine

A

phosphatidate and ethanolamine

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57
Q

phosphatidylinositols and sphingosine derivatives act as…..

A

intracellular signals

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58
Q

phosphatidylinositol and its phosphorylated derivatives regulate…

A

cell structure and metabolism

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59
Q

phosphatidylinositol 4, 5 Biphosphate (PIP2)

A

-exists in the cytoplasmic face of plasma membranes
-serves as a reservoir of messenger molecules that release in response to extracellular signals

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60
Q

_____________ hydrolyzes PIP2 to IP3 and diaclyglycerol, which are intracellular messengers

A

phospholipase C

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61
Q

Inositol phospholipids serve as points of….

A

nucleation

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62
Q

signaling proteins bind to ____________________ in the plasma membrane to initiate the forming of multienzyme complexes at the membranes cytosol surface

A

(PIP3)

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63
Q

ceramide and sphingomyelin are regulators of…

A

protein kinases

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64
Q

ceramide/its derivatives are involved in the regulation of:

A

-cell division
-differentiation
-migration
-programmed cell death

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65
Q

eicosanoids

A

paracrine hormones, act only on cells near the point of hormone synthesis instead of being transported in the blood

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66
Q

eicosanoids are involved in:

A

-reproductive function
-inflammation
-forming blood clots
-regulating blood pressure
-gastric acid secretion

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67
Q

eicosanoids are derived from…

A

arachidonic acid

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68
Q

what are the 4 classes of eicosanoids

A

prostaglandins
thromboxanes
leukotrines
lipoxins

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69
Q

prostaglandins

A

class of eicosanoids that have a 5 carbon ring

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70
Q

prostaglandins functions

A

-stimulate contraction of smooth muscle of uterus
-affect blood flow to specific organs, wake/sleep cycle, hormone responsiveness
-elevate body temp
-cause inflammation/pain

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71
Q

thromboxanes

A

class of eicosanoids that have a 6 carbon ring with an ether
-produced by platelets AKA thrombocytes

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72
Q

thromboxanes functions

A

act in formation of blood clots and reduction of blood flow to site of clot

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73
Q

leukotrines

A

class of eicosanoids that have 3 conjugated double bonds

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74
Q

leukotrines functions

A

-theyre powerful biological signals
-leukotrine D4 induces the contraction of smooth muscle lining airways to the lung

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75
Q

lipoxins, and their function

A

class of eicosanoids that are linear and have several hydroxyl groups
-potent anti inflammatory agent

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76
Q

what are steroids

A

oxidized derivatives of sterols.

-dont have the alkyl chain thats attached to ring D of cholesterol
-more polar than cholesterol
-they move through the blood stream on protein carriers to target tissues

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77
Q

what are the steroids derived from cholesterol

A

-testosterone
-cortisol
-prednisone
-B-Estradiol
-Aldosterone
-Brassinolide

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78
Q

Vitamins A and D are…

A

hormone precursors

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79
Q

what are vitamins?

A

compounds essential to health that cant be synthesized

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80
Q

fat soluble vitamins

A

A, D, E, K

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81
Q

Vitamin D3 (cholecalciferol)

A

formed in skin from 7-deydrocholesterol, in a photochemical reaction driven by UV
-not biologically active
-converted by enzymes in the liver/kidney to calcitriol

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82
Q

what is calcitriol

A

hormone that regulates calcium uptake in the intestine, and calcium levels in kidney/bones

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83
Q

vitamin A1 - all trans retinol

A

acts in processes of development like cell growth and differentiation and vision
-can be stored for some time in the body

-can be converted enzymatically to all trans retinoic acid

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84
Q

all trans retinoic acid

A

retinoid hormone that acts thru a family of nuclear receptor proteins to regulate gene expression

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85
Q

carotenoids

A

natural products, extensive system of conjugated db’s, to make strong absorption of visible light
-B carotene pigment is a source of vitamin A

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86
Q

precursors of retinoids

A

B Carotene and Vitamin A1

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87
Q

Vitamins E and K and the liquid quinones are

A

oxidation reduction cofactors

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88
Q

vitamin E

A

collective name for a group of lipids- the tocopherols

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89
Q

tocopherols

A

hydrophobic compounds, containing a substituted aromatic ring and a long isoprenoid side chain.
-associated w cell membranes, lipid deposits, and lipoproteins
-biological antioxidants

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90
Q

vitamin K

A

has an aromatic ring that undergoes cycle of oxidation and reduction during the formation of prothrombin

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91
Q

prothrombin

A

blood plasma protein essential in blood clotting

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92
Q

ubiquinone (coenzyme Q) and plastoquinone

A

isoprenoids.
-they function as lipophilic electron carriers in the ox-redux reactions that drive ATP synthesis in mitochondria and chloroplasts

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93
Q

dolichols

A

isoprenoid alcohols.
-they activate and anchor sugars to cellular membranes.
-sugar groups are used in the synthesis of complex carbs, glycolipids, and glycoproteins
-they allow attached sugars to participate in sugar transfer reactions

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94
Q

conjugated dienes

A

-have carbon chains with alternating single and double bonds
-allow delocalization of electrons
-compounds can be excited by light
-many natural pigments are lipidic conjugated dienes

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95
Q

eicosanoids are made from _____ and act as ______ hormones

A

-arachidonate
-paracrine

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96
Q

glycerophospholipids, sphingolipids, and sterols:

A

-insoluble in water
-spontaneously form microscopic lipid aggregates when mixed with water

97
Q

the lipid bilayer is ____ in water

A

stable

98
Q

micelles

A

spherical structures with amphipathic molecules arranged with hydrophobic regions in the interior, and hydrophilic head groups on the exterior.

-favored when cross-sec areas of head group is greater than the acyl side chains

99
Q

vesicle (liposome)

A

forms spontaneously when a bilayer sheet folds back on itself to form a hollow sphere

100
Q

bilayer formation

A

lipid aggregate in which two lipid monolayers form a 2D sheet

-favored when cross-sec areas of head group and acyl side chains are similar

101
Q

fluid mosaic

A

pattern formed from individual lipid and protein units in a membrane
-the pattern can change while maintaining the permeability membrane

102
Q

what are the functions of biological membranes

A
  • permit shape changes that accompany cell growth and movement

-permits exocytosis, endocytosis, and cell division

-serve as molecular gatekeepers

103
Q

transporters (membrane)

A

aka translocases.
move organic solutes, inorganic ions across membrane

104
Q

receptors (membrane)

A

sense extracellular signals and trigger molecular changes in the cell

105
Q

ion channels (membrane)

A

mediate electrical signaling between cells

106
Q

adhesion molecules (membrane)

A

hold neighboring cells together

107
Q

single membrane surrounds:

A

ER
golgi apparatus
lysosomes
small vesicles

108
Q

double membrane surrounds:

A

nucleus
mitochondria
chloroplasts

109
Q

membrane trafficking

A

membrane lipids and proteins are synthesized in the ER and move to their destination organelle or plasma membrane

110
Q

lipids and proteins undergo covelent modification in the…

A

golgi apparatus

111
Q

what changes happen during membrane trafficking

A

sphingolipids and cholesterol largely replace phosphatidycholine

plasma membrane lipids are asymmetrically dist between the layers of the bilayer

112
Q

groups of membrane proteins

A

-receptors for extracellular signals
-transporters to carry polar or charged compounds across the PM or between organelles
-enzymes

113
Q

posttranslational mod of membrane proteins

A

glycosylation and attachment of +1 lipids (which serve as hydrophobic anchors or targeting tags)

114
Q

glycosylation

A

attachment of oligosaccharides to proteins

115
Q

integral membrane proteins

A

firmly embedded within the lipid bilayer

116
Q

peripheral membrane proteins

A

associate with the membrane through electrostatic interactions and H bonding

117
Q

amphitropic proteins

A

associate reversibly with membranes (found in membranes and cytosol)

118
Q

monotopic proteins

A

have small hydrophobic domains that interact with only a single leaflet of the membrane

119
Q

bitopic proteins

A

span the bilayer once, extending on either surface. have a hydrophobic seq somewhere in the molecule

120
Q

polytopic proteins

A

cross the membrane several times, have multiple hydrophobic seq of 20 residues, that each cross the membrane when in a-helical conformation

121
Q

_____% of proteins in organisms are integral proteins

A

20-30

122
Q

a-helical seq of 20-25 residues

A

is long enough to span the thickness of the lipid bilayer.
stabilized by H bonding and the hydrophobic effect

123
Q

hydropathy index

A

the free energy change associated with the movement of an AA side chain from a hydrophobic environment to water
-ranges fron exergonic to endergonic

124
Q

overall hydropathy index

A

estimated by summing up the free energies of transfer for all residues in the seq

125
Q

hydropathy plot

A

avg hydropathy index, plotted against residue number.

window= segment of given length

hydropathy index= y axis (avg hydropathy for a window)

residue number = x axis (residue number in the middle of the window)

126
Q

B Barrel

A

structural motif, 20+ transmembrane segments form B sheets that line a cylinder
-stabilized by H bonds

127
Q

porins

A

proteins that allow polar solutes to cross outer membrane of gram negative bacteria
-have B barrels lining the trans membrane passage

128
Q

B strands, B conformation

A

7-9 residues needed to span a membrane
alternating side chains project above and below the sheet

129
Q

B strands of membrane proteins

A

-every 2nd residue in the membrane spanning segment is hydrophobic, and interacts w lipid bilayer

-aromatic side chains are commonly found at the lipid protein interface

130
Q

__ and __ side chains serve as membrane interface anchors

A

Tyr , Trp

131
Q

positive inside rule

A

positively charged Lys and Arg residues (in the extra membrane loop of membrane proteins) occur more commonly on the cytoplasmic face

132
Q

acyl groups in bilayer interior
liquid order LO state

A

gel like state where all types of motion of individual molecules are strongly constrained

133
Q

acyl groups in bilayer interior
liquid disordered LD state

A

state in which the individual hydrocarbon chains are in constant motion

134
Q

lipids move freely in their monolayer

A

mobile within their monolayer.
rotation of phospholipids around their axes can occur.
phospholipids can move via lateral diffusion
both movements are rapid and random.

135
Q

the smooth ER membrane has proteins that catalyze the…

A

flip flop of membrane lipids AKA transverse diffusion.
Aka flippases

136
Q

lipids and proteins diffuse ____ in the bilayer.

A

laterally.

individual lipids undergo Brownian movement.

137
Q

FRAP

A

fluorescence recovery after photobleaching
-the rate is a measure of the rate of lateral diffusion of lipids

138
Q

the lipid bilayer behaves as…

A

a fluid, permitting the movement of lipids and proteins.

139
Q

fatty acid composition affects membrane fluidity

A

-long chain saturated fatty acids tend to pack into LO phase
-kinks in unsat fatty acids favor the LD state
-short chain fatty acyl groups favor the LD state

140
Q

sterols impact on membrane fluidity

A

-can interact with phospholipids that have unsat fatty acyl chains, constraining their motion

-can associate with sphingolipids, and phospholipids with long saturated fatty acyl chains, making the bilayer fluid

141
Q

transbilayer, flip flop movement has..

A

large positve free energy change

142
Q

membrane proteins facilitate the translocation of

A

lipid molecules

143
Q

flippases

A

-catalyze translocation of amino-phospholipids phosphatidyethanolamine (PE) and phosphatidylserine (PS) from the extracellular to the cytoplasmic leaflet of the PM

144
Q

floppases

A

move PM phospholipids and sterols from the cytoplasmic leaflet to the extracellular leaflet
-ATP dependent
-ABC transporter familu

145
Q

scramblases

A

move any membrane phospholipid across the bilayer down its conc gradient
-not dependent on ATP, some need Ca2+
-leads to randomization of head group composition of the 2 faces of the bilayer

146
Q

phosphatidylinositol transfer proteins

A

move phophatidylinositol lipids across lipid bilayers

147
Q

hop diffusion of lipids

A

-lipids diffuse laterally within small regions
-movement from one region to another (hop) is rare

148
Q

some membrane proteins can diffuse freely, others cant

A

membrane proteins are limited in movement by associating to form large aggregates/patches

and anchoring to internal structures

149
Q

microdomains/rafts

A

clusters of cholesterol and sphingolipids that make the bilayer thicker and more ordered.
can be up to 50% of the cell surface

150
Q

proteins must have hydrophobic helical sections long enough to..

A

segregate into thicker bilayer regions of rafts

151
Q

lipid rafts are enriched in

A

-proteins with 2 long chain saturated fatty acids covalently attached through Cys residues
-GPI anchored proteins.

152
Q

caveolae

A

specialized rafts

153
Q

cavolin

A

integral protein that binds to the cytoplasmic leaflet of the PM
-it forms dimers
-associates with cholesterol rich membrane regions
-forces the bilayer to curve inward to make caveolae

154
Q

membrane curvature is important because

A

curvature changes are central to the ability of membranes to undergo fusion with other membranes and still maintain continuity

155
Q

to move phospholipids from inner leaflet to outer leaflet of PM, which enzyme?

A

flopppase

156
Q

which movement of membrane phospholipids is slowest

A

transbilayer diffusion

157
Q

_________ compounds can dissolve in the lipid bilayer and cross a membrane unassisted

A

nonpolar

158
Q

_________ compounds and ions require membrane protein carriers to cross membrane

A

polar

159
Q

simple diffusion

A

movement of solute from high conc to low conc

160
Q

membrane potential, Vm

A

transmembrane electrical gradient, occurs when ions of opposite charges are separated by a permeable membrane

-can produce forces that opposes ion movements that inc Vm
-drives movements that reduce Vm

161
Q

electrochemical gradient

A

determines direction in which a charged solute moves across a membrane

made of:
chemical gradient
electrical gradient (Vm)

162
Q

passive transport AKA facilitated diffusion

A

facilitate movement down a conc gradient, increasing transport rate

163
Q

active transport

A

moves substrates across membranes against a conc gradient or electrical potential

164
Q

primary active transport

A

use energy provided by chemical reaction
solute accumulation is coupled to an exergonic chemical reaction

165
Q

secondary active transport

A

couple uphill transport of one substrate with downhill transport of another

-endergonic transport of one solute is coupled to the exergonic flow of a different solute that was pumped uphill by primary active transport

166
Q

transporters proteins reduce energy of activation for diffusion by

A

-forming noncovalent interactions with the dehydrated solute
-providing a hydrophilic transmembrane pathway

167
Q

ion channels

A

provide aqueous path across membrane that inorganic ions can diffuse at very high rates

168
Q

features of ion channels

A

most have a gate regulated by a signal
typically show specificity for an ion
not saturable with their ion substrate
flow stops when gate is closed or when theres no electrochemical gradient

169
Q

whats the difference between ion channels and transporters

A

ion channel has a single gate
transporter has alternating gates

170
Q

glucose transporter of erythrocytes GLUT1 mediates…

A

passive transport

171
Q

glucose enters the erythrocyte by passive transport via…

A

GLUT1

172
Q

GLUT1

A

integral membrane protein, has 12 hydrophobic segments that form 12 membrane spanning helices
-helices are amphipathic

173
Q

glucose transport to erythrocytes

A

-cycles between 2 conformations:
T1= glucose binding site exposed on the outer membrane surface
T2= glucose binding site exposed on the inner surface

174
Q

transport of glucose into myocyte by GLUT4 is regulated by…

A

insulin

175
Q

chloride bicarbonate exchanger

A

anion exchanger essential in CO2 transport to the lungs from tissues
-passive transport system
-no net transfer of charge

176
Q

cotransport systems

A

simultaneously transport 2 solutes across a membrane

177
Q

cotransport- antiport and symport

A

antiport- move in opposite direction
symport- move in same direction

178
Q

uniport system

A

carry only one substrate

179
Q

active transport is thermodynamically..

A

unfavorable- endergonic.

must be coupled to an exergonic process
results in accumulation of solute above eq point

180
Q

free energy change for transport of an uncharged solute

A

no bonds broken and change in G is zero

181
Q

free energy change for transport of an ion

A

without movement of an accompanying counter ion the process is electrogonic (produces electrical potential)

182
Q

P type ATPases undergo…

A

phosphorylation during their catalytic cycles

183
Q

P type ATPases

A

family of cation transporters that are phosphorylated by ATP as part of transport cycle

-integral proteins with 8 or 10 predicted membrane spanning regions
-sensitive to inhibition by the transition state analog vanadate

184
Q

Na+ K+ Atpase

A

animal cell antiporter for Na+ and K+

couples phosphorylation dephosphorylation of the Asp to the movement of Na+ and K+ against their electrochemical gradients
-maintains low Na+ and high K+
-essential for action potentials

185
Q

H+ atpase

A

plant and fungi transporter

186
Q

SERCA pump (sarcoplasmic ER Ca2+ ATPase)

A

uniporter for Ca2+ ions

187
Q

P type ATPases

A

critical Asp residue in the P domain undergoes phosphorylation and dephosphorylation

188
Q

mechanism for SERCA

A

each catalytic cycle moves 2 Ca2+ ions across the membrane and converts an ATP to ADP and Pi

E1 and E2 interconvert

189
Q

V type ATPases

A

class of proton transporting ATPases responsible for acidifying intracellular compartments

V0 is a proton channel
V1 is the ATP binding site and ATPase activity

190
Q

F type ATPases

A

catalyze uphill transmembrane passage of protons driven by ATP hydrolysis

F0 provides pathway for protons
F1 protein uses energy of ATP to drive proteins uphill

191
Q

F type ATPases catalyze reactions in both directions

A

a large proton gradient can supply the energy to drive ATP synthesis
when functioning in this direction, F type ATPases are called ATP synthases

192
Q

ABC transporters

A

ATP driven transporters that pump substrates across a membrane against a conc gradient
- 2 ATP binding domains and 2 trans membrane domains

193
Q

mechanism of ABC transporters

A

substrates move across the membrane when 2 forms of the transporter interconvert
-this is driven by ATP hydrolysis

194
Q

multidrug transport, MDR1

A

human ABC transporter with broad substrate specificity
-its encoded by the ABCB1 gene and removes toxic compounds
-creates resistance of tumors to drugs

195
Q

Na+ glucose symporter

A

takes up glucose from the intestine in a process driven by the downhill flow of Na+

196
Q

ion gradients provide energy for secondary active transport

A

strong thermodynamic tendency for Na+ to move into the cell provides energy needed for the transport of gluclose into cell

197
Q

peptide ionophore called valinomycin is an antibiotic

A

it acts as a shuttle to carry K+ across the membrane down its conc gradient, and deflating that gradient

198
Q

ionophores

A

compounds that shuttle ions across membranes

199
Q

aquaporins

A

provide channels for movement of water molecules across plasma membranes

-each protein has a specific location/role

-low activation energy suggests water moves in continuous stream

-doesnt allow for passage of protons

200
Q

ion selective channels

A

-allow rapid movement of ions across membranes

-not saturable

-gated in response to cellular event

201
Q

ligand gated channels

A

binding of an extracellular or intracellular small molecule forces an allosteric transition in the protein, which will open or close the channel

202
Q

voltage gated ion channels

A

change in the transmembrane electrical potential causes a charged protein domain to move relative to the membrane, opening or closing the channel

203
Q

patch clamping

A

currents are measured through a region of the membrane surface that has only one or a few ion channel molecules

204
Q

the structure of a K+ channel

A

channel is only wide enough to accommodate an unhydrated metal ion like K+

K+ passes 100000 times more easily than Na+

205
Q

mechanism of K+ channel

A

polar transmembrane passage will precisely fit the K+ ion

206
Q

what membrane will move a hydrophobic molecule from high to low conc

A

this wont need a transporter
-simple diffusion

207
Q

Ion channels/transporters (the gate)

A

when the gate is open, ions move through ion channel at a rate thats only limited by the max rate of diffusion

208
Q

signal tranduction

A

conversion of info into a chemical change

-the signal represents info thats detected by reporters

-conversion of the signal into a cellular response involves a chemical process

209
Q

signal specificity

A

created by precise molecular complementarity by the signal and receptors

-mediated by weak noncovalent forces

210
Q

signal sensitivity

A

results from high affinity of receptors for their ligands

211
Q

signal amplification

A

results when an enzyme is activated by a receptor and catalyzes the activation of many molecules of a 2nd enzyme in an enzyme cascade

212
Q

modular signaling

A

has multiple domains to recognize specific features
-this allows cells to mix and match a set of signaling molecules

213
Q

scaffold proteins

A

non enzymatic proteins that bring together enzymes that interact in cascades

214
Q

desensitization of receptor systems

A

receptors are no longer responsive to a signal
-occurs when a signal is present continuously

215
Q

integration of receptor systems

A

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

216
Q

signaling pathways are divergent

A

branched rather than linear
-it occurs when a signal is present continuously

217
Q

response localization in signaling

A

cells confine signaling system components to a structure to regulate processes locally

218
Q

features of signal transduction

A

-signal/ligand interacts with receptor
-activated receptor interacts with cell machinery to make a second signal or change in protein activity
-cell metabolic activity changes
-transduction event ends

219
Q

G protein coupled receptors (GPCRs)

A

receptors that act through a member of the guanosine nucleotide binding family

220
Q

three parts of the signal transduction through GPCRs

A

-PM receptor with 7 transmembrane helical segments

-G protein that cycles from active GTP bound and inactive GDP bound forms

-an effector enzyme or ion channel in the PM thats regulated by the activated G protein

221
Q

first messenger signal

A

extracellular signal that activates a receptor from outside the cell

222
Q

second messenger signal

A

low MW metabolite or inorganic ion that changes in conc due to the effector enzyme
-functions to activate or inhibit downstream targets

223
Q

adrenergic receptors

A

protein receptors in the PM that bind epinephrine
(4 types : a1, a2, B1, B2)

224
Q

B-adrenergic receptors

A

B1 and B2 protein receptors

225
Q

agonist (in signaling)

A

molecule that binds a receptor and produces effects of the natural ligand

226
Q

antagonist (in signaling)

A

analog that binds the receptor and blocks the effects of the agonist including the natural ligand

227
Q

GPCRs

A

span the membrane 7 times and interact with heterotrimeric G proteins

228
Q

heterotrimeric G proteins

A

conserved family of signaling proteins with the subunits a, B, and γ

-a subunit is the binding site for GDP and GTP

229
Q

the B adrenergic pathway

A

GPCR acts as a guanosine nucleotide exchange factor GEF

-G protein stimulates its effector, so its referred to as stimulatory G protein: Gs

230
Q

adenylyl cyclase

A

integral protein in the PM that catalyzes synthesis of cAMP from ATP when associated with Gsa

231
Q

the synthesis and hydrolysis of cAMP

A

cAMP activates pKA

degradation of cAMP reverses activation of pKA

232
Q

the GTPase switch

A

Gsa has GTPase activity that switches Gsa to its inactive form by converting its GTP to GDP

233
Q

cyclic AMP activates protein Kinase A

A

cAMP dependent protein kinase (A or pKA)= activated by cyclic AMP

-catalyzes the phosphorylation of Ser and Thr of target proteins

234
Q

R2C2 complex

A

catalytically inactive, the auto-inhibitory domain of each R subunit occupies the substrate binding of each C subunit

235
Q

cyclic AMP is an allosteric activator of pKA

A

binding of cAMP yields 2 active C subunits

236
Q

displacement of an autoinhibitory domain mediates allosteric activation of many protein kinases

A

structure of the substrate binding in pKA is the prototype of all known protein kinases

237
Q

consensus seq

A

contain the target for phosphorylation (Ser or Thr) by protein kinases

238
Q

FRET

A

measures non-radiative transfer of energy from fluorescent probes attached to the protein
-to determine if 2 proteins interact and where in the cell they interact

239
Q

measuring cAMP with FRET

A

-when cAMP is low, R and C subunits of pKA are associated and FRET is exhibited

-when cAMP rises, R and C subunits of pKA dissociate and FRET stops

-when pKA is inactive, Ser is not phosphorylated and FRET is not observed

-when pKA is active, the Ser is phosphorylated and FRET is observed

Biochem (8 decks)

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