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Foundations > Week 2 Foundations - Sheet1-1 > Flashcards

Week 2 Foundations - Sheet1-1 Flashcards

1
Q

Glycolysis: Phase I requires an investment of _______

A

2 ATP and Glucose,

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2
Q

Glycolysis: Phase II or the generating phase provides _____

A

2 ATP (net; 4 for this phase) and 2 NADH and 2 pyruvate

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3
Q

aldolase

A

glycolysis–cleaves glucose into two molec

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4
Q

hexokinase

A

catylizes the first rxn of glycolysis in most tissue. The rxn requires an invenstment of ATP –> ADP. Regulation primarily by substrate and product.

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5
Q

glucokinase

A

catylizes the first rxn of glycolysis in LIVER. This rxn requires an investment of ATP–>ADP. Note that this enzyme has a larger Km. Regulation primarily by substrate and product.

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6
Q

glucose 6-phosphate

A

result of the rxn from glucose using hexokinase/glucokinase. This second molec in glycolysis can be used in gluconeogenesis, glycogenolosis, and pentose phosphate pathway.

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7
Q

Phosphoglucose isomerase (a.k.a. phosphoglucomutase)

A

reversably converts glucose 6-phosphate fructose 6-phosphate

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8
Q

phosphofructokinase-1

A

fructose 6-phosphate fructose 1,6-bisphosphate. This rxn requires ATP–>ADP and is the last investment. Allosteric regulation by (+) AMP and fructose 2,6-bisphosphate (produced by PFK-2); (-) ATP and citrate

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9
Q

Fructose 2,6-bisphosphate

A

produced by PFK-2 in the reaction Fructose 6-phosphate Fructose 2,6-bisphosphate; this serves as an inhibitor of PFK-1. This reaction is not a part of glycolosis and serves as a secondary messenger

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10
Q

If there is a high [fructose 6-phosphate], what will happen? Think glycolysis…

A

PFK-2 will convert to fructose 2,6-bisphosphate, which allosterically activates PFK-1 and converts fructose 6-phosphate to fructose 1,6-bisphosphate–thus increasing glycolysis. PFK-2 is activiated by glucagon and AMP

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11
Q

pyruvate kinase (PK)

A

converts phosphenolpyruvate —> pyruvate (provides ADP–>ATP). Regulated by substrate and product in ADULT tissue.

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12
Q

fight or flight response

A

epinephrine–>heterotrimeric G protein coupled receptor–>cAMP, PKA—> glycogenolosis—>glucose into circulation

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13
Q

glycogenolosis

A

(glycogen–>glucose 1-phosphate—-> glucose 6-phosphate) hepatocyte)—-> glucose

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14
Q

Important relationship between ATP and PFK-1

A

ATP is substrate and regulator of PFK-1. There are to binding sites: 1 for use in kinase activity and 2 allosteric inhibition site. At higher concentrations ATP is an allosteric inhibitor.

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15
Q

PFK-1 has an overall significance in glycolysis…

A

rate limitiing step

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16
Q

PK-M2 splice varient

A

Normally expressed only in embryonic tissue, but can be expresed in cancer. This is thought to contribute to cancer cells’ altered metabolism

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17
Q

Cancer cells have an increased rate of glucose uptake. How does PK-M2 help a cancer cell?

A

PK-M2 is a low activity isoform of pyruvate kinase. This slows down glycolysis flux and increases the diversion of substrates from glycolysis.

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18
Q

2,3-bisphosphoglycerate

A

binds at a site distant from the oxygen-binding site and regulates the O2-binding affinity of hemoglobin. 2,3-BPG stabilizes deoxyhemoglobin; thus increaseing O2 delivery to tissue. Draw out mechanism and enzymes

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19
Q

Pathology: PDH deficiency
poison, e.g. cyanide
ischemia (lack of O2)
ethanol

Implications for glycolysis?

A

If there is a problem downstream of pyruvate, the cell must get all its ATP through glycolysis, with lactic acid as the product. This will decrase blood pH

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20
Q

Ischemia

A

is a loss of blood perfusion and oxygen delivery to tissue. If a cell doesn’t have oxygen. . .

The NADH/NAD+ ratio increases
Product inhibition of the pyruvate dehydrogenase reaction
Substrates for lactate dehydrogenase (pyruvate and NADH) favors lactate production

The AMP / ATP ratio increases
AMP acts as an allosteric activator of PFK-1
AMP activates AMP-K, which activates PFK-2, making more F-2,6-bP, activating PFK-1
The rate of glycolysis is increased

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21
Q

HIF pathway and ischemia

A

ischemia means tissue hypoxia–> HIF pathway activated. Hypoxia-inducible factor (HIF) regulates gene expression such that glycolysis increases. One way is through activation of PDH kinase, which phosphorylates and shuts down PDH –> so [pyruvate] increases and Lactate DH activity increases.

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22
Q

two essential amino acids in diet

A

linoleic (18:2), linolenic (18:3)

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23
Q

hormone sensitive lipase reacts with what three hormones?

A

stored fat mobilization occurs due to glucagon, epinephrine, norepinephrine

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24
Q

How does palimtoyl-CoA cross the impermeable inner mitochondrial matrix?

A

It takes the carnitine shuttle.

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25
Q

Enoyl-CoA hydratase can only accept what kind of double bond?

A

can only accept trans-double bonds, but most unsaturated FA in diet have trans!? So **enoyl CoA isomerase converts cis to trans in previos step

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26
Q

What happens when the liver’s store of glycogen is depleted?

A

3-hydroxybutyrate, acetoacetate

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27
Q

The ______ is the site of ketone body synthesis

A

Liver

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28
Q

Ketone bodies produced in the liver can be used as fuel by

A

brain, heart, and skeletal muscle

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29
Q

The absence of elevated ketone bodies in a hypoglycemic patient suggests a defect in ____________________, such as ________________.

A

fatty acid metabolism; medium chain acyl-CoA dehydrogenase deficiency (MCAD).

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30
Q

activation of fatty acids is required for beta-oxidation. This requires…

A

binding to acyl-CoA. This involves Fatty Acyl Co-A synthetase and requires ATP—> AMP. So ATP + FA —-> Fatty Acyl CoA + AMP + 2Pi

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31
Q

Reye Syndrome

A

Multisystem organ failure, particularly affecting the brain and liver, caused by mitochondrial dysfunction

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32
Q

What are the two routes to gain NADPH?

A

malic enzyme (malate—> pyruvate) and the pentose phosphate pathway

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33
Q

malate dehydrogenase

A

enzyme of the CAC. Converts Malate—->OAA (NAD+ —> NADH)

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34
Q

citrate lyase

A

cytosolic: converts citrate (from mito; CAC) to acetyl CoA and OAA. **Acetyl CoA can then enter FA synthesis

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35
Q

In conditions of excess energy, ___________________ is inhibited by a high NADH/NAD+ ratio. This drives citrate towards fatty acid synthesis.

A

The CAC is inhibited and specifically inhibits **isocitrate dehydrogenase, which is responsible for increasing [citrate] –> leaves mito, is converted by citrate lyase to acetyl CoA (FA synthesis) and OAA (which can reenter mito).

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36
Q

In lipid synthesis, _____ is produced to continue glycolysis

A

NAD+

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37
Q

NADPH is involved in what kind of pathways

A

biosynthetic pathways

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38
Q

pentose phosphate pathway (main point)

A

biosynthetic purposes and production of NADPH

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39
Q

The pyruvate / malate cycle has two functions in lipogenesis

A

1) Transports acetyl CoA from the mitochondria to the cytosol. 2) Malic enzyme generates NADPH to power fatty acid synthesis.

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40
Q

ACC

A

acetyl CoA carboxylase-first step of fatty acid synthesis. (Biotin!) Regulation: (+) Citrate allosterically activates (feed forward),
Insulin increases transcription, Xylulose 5-phosphate increases transcription, Insulin stimulates dephosphorylation, activating the enzyme; (-)
Palmitoyl CoA allosterically inhibits (product inhibition), Phosphorylation by AMP-PK inhibits, Glucagon –> cAMP –> PKA –> inhibitory phosphorylation

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41
Q

feed forward allosteric regulation

A

[substrate] of enzyme regulates

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42
Q

__________inhibits carnitine palmitoyl transferase I, preventing β-oxidation of newly synthesized fatty acids.

A

Malonyl CoA

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43
Q

AMPK or AMP-PK

A

AMP activated protein kinase. Responds to an increase in [AMP] (which means low ATP) and by phophorelating key enzymes to increase energy levels (and shut off FA synthesis and other biosynthetic paths.)

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44
Q

In β-oxidation of fatty acids, the reaction sequence is:

A

(occurs in mito) oxidation, hydration, oxidation, bond cleavage

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45
Q

In fatty acid synthesis, the reaction sequence is:

A

(occurs in cytoplasm) bond formation (decarboxylation), reduction, dehydration, reduction–one enzyme does all this!

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46
Q

Fatty acid synthase

A

Primary enzyme responsible for FA synthesis. Has two important active sites with sulfur groups–substrate flips back and forth adding carbon. Produces palmitate

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47
Q

Cofactor for FA synthase?

A

acetyl CoA?

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48
Q

FA synthesis: Elongation

A

Palmitoyl CoA can be elongated, two carbons at a time, in the endoplasmic reticulum. Malonyl CoA donates the two carbons, and the added keto group undergoes the same reduction, dehydration, and reduction to produce a saturated fatty acyl chain. Palmitate is produced and is saturated!

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49
Q

FA synthesis: Unsaturation

A

The body can unsaturate carbon carbon bonds if they are at least nine carbons away from the ω end.

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50
Q

ω-3 and ω-6 fatty acids are obtained from plant and fish oils, and are essential dietary precursors for synthesizing ________.

A

eicosonoids–paracrine hormones (substances that act only on cells near the point of hormone synthesis). ***Aracadonic acid is the precursor to eicosonoids. Nonsteroidal antiinflammatory drugs such as aspirin and ibuprofen block aracadonate from conversoin to eicosonoids

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51
Q

__________ and ________are the two most important dietary unsaturated fatty acids

A

Linoleic (18:2(9),1(2) and linolenic (18:3(9),(12),(15), (((arachidonic (10:4) also))))

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52
Q

Arachidonic acid

A

is a precursor of prostaglandins. It can not be synthesized de novo, because it has carbon – carbon double bonds near the ω carbon. Linolenic acid consumed in the diet can be converted to arachidonic acid by elongation and introducing two carbon – carbon double bonds.

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53
Q

FA synthesis occurs in the _____

A

Liver

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54
Q

Triacylglycerol is made up of

A

three fatty acyl chains linked to a glycerol backbone. Glycerol 3-phosphate is the source of the glycerol backbone.

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55
Q

The two enzymes that make glycerol 3-phosphate

A

glycerol kinase (FROM LIPOLYSIS in liver) (glycerol—-> glycerol 3-phosphate (Requires ATP–> ADP)), glycerol 3-phosphate dehydrogenase (FROM GLYCOLYSIS in liver and adipocytes) (dihydroxyacetone phosphate —> glyceral 3-phosphate (NADH–> NAD+))

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56
Q

lipoprotein lipase (LPL)

A

LPL cleaves off fatty acids, which then enter cells. They undergo β-oxidation for energy in muscle cells, and they are stored as triacylglycerols in adipocytes.

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57
Q

storage of lipids requires what active process in adeipocytes?

A

glycolysis to produce glycerol 3-phosphate via glycerol 3-phosphate dehydrogenase

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59
Q

phospholipids

A

use glycerol as a backbone. Have two FAs and Head Group

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60
Q

___________are mainly used in cell membranes, but also are constituents of lipoproteins, bile, and lung surfactant.

A

Glycerophospholipids

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61
Q

The inner mitochondrial membrane is rich in ….

A

cardiolipin

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62
Q

cardiolipin

A

is a component of the inner mitochondrial membrane. It is formed by linking phosphatidyl glycerol (a glycerophosphate with a glycerol head group) with CDP diacylglycerol. Is more ridged and larger than most membrane lipids—> impermiability

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63
Q

Sphingolipids

A

use ceramide instead of glycerol for their backbones. Ceramide is derived from serine and palmitoyl CoA.

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64
Q

The most important sphingolipid is ______________, which is present in the myelin sheaths of nerve fibers. The head group is choline.

A

sphingophospholipid sphingomyelin

65
Q

Surfactants are required in the lungs to prevent ______

A

alveolar collapse

66
Q

The ratio of what two lipids in amniotic fluid is a useful indicator of gestational progress

A

sphingomyelin to phosphatidylcholine

67
Q

leptin

A

released from adipocytes–>acts on hypothalmus—>satiety (behavior)

68
Q

Leptin and STAT

A

JAK receptors bind leptin, JAK phosphorylates STAT—> which acts as transcription factor for anorexigenic factors that depress appetite

69
Q

malonyl CoA decarboxylase

A

Involved in FA synthesis. Opposite of ACC. Converts malonyl CoA into acetyl CoA (and loses CO2)

70
Q

cell structure: Phospholipids

A

establish basic membrane structure. Can be glycosylated

71
Q

cell structure: Cholesterol

A

stiffens membranes

72
Q

cell structure: Glycolipids

A

have sugar component (minor population in membrane). Can be neutral or negatively charged. Glycolipids carry out functions in cell recognition and adhesion, and charged glycoproteins can influence the electrical properties of membranes. Enriched in neurons and apical surfaces of epithelial cells.

73
Q

cell structure: Phosphatidylinositols

A

involved in cell signaling (minor population in membrane). Kinases can phosphorelate different portions of the inositol portion

74
Q

amphipathic molecules

A

possess hydrophobic and hydrophilic regions

75
Q

inositol 1,4,5 trisphosphate (IP3)

A

binds to smooth endoplasmic reticulum and opens calcium ion channels to release Ca++ into the cytoplasm, which is then able to bind and modulate the functions of many calcium-binding proteins

76
Q

DAG

A

diacylglycerol– serves as docking site for protein kinase C.

77
Q

phosphoglyceride synthesis

A

in ER

78
Q

sphingomyelin synthesis

A

made from sphingosine in the Golgi

79
Q

Glycolipid synthesis

A

made from sphingosine in the Golgi

80
Q

flipases

A

recognizes specific phospholipids and flip them between leaflets

81
Q

There is a net ____ charge on the cytosolic side of the plasma membrane

A

negative, due to serine and amine functionalities. If there is a negative charge on outside–> signals poor cell health

82
Q

lipid rafts

A

-Special membrane domains composed of specific types of lipids and proteins
•Rich in sphingolipids, cholesterol, and certain proteins
•May be sorted to transport vesicles and involved with *signal transduction events and other specialized functions.

83
Q

Glycocalyx

A

function as barrier of protection. Have covelently attahced sugar groups.

84
Q

Three ways proteins can be organized in membranes.

A

A: self-assembly into aggregates; B: tethered to extracellular molecules; C: tethered to intracellular molecules; D: bound to proteins on adjacent cells. Also, cell junctions (specifically, tight junctions) can establish apical and baso-lateral domains in membranes of epithelial cells.

85
Q

The integral membrane protein integrin

A

binds to extracellular molecules such as collagen and fibronectin, as well as to intracellular elements such as the cytoskeleton. Binding to the extracellular matrix can organize integrins into patches, and affect their function as environmental sensors.

86
Q

Cadherin

A

is a large integral membrane protein that self-associates in the presence of calcium ions. It is an important adhesive molecule, linking cells together that express the same type of cadherin

87
Q

Functions of the ER:

A

§ Synthesizes protein (RER). SER; § Synthesizes lipid (RER and SER). § Metabolizes and detoxifies harmful compounds (SER). § Helps regulate Ca++ levels in the cell (RER and SER).

88
Q

RER produces

A

All integral membrane proteins (including ER, Golgi, lysosomes, endosomes, secretory vesicles, and plasma membrane), except those of mitochondria and peroxisomes. § Luminal and secreted proteins.

89
Q

what determines whether a polyribosome becomes attached to an ER membrane or remains free-floating in the cytoplasm?

A

Contained within produced polypeptide itself: ER signal sequence

90
Q

prostagladins

A

any of various oxygenated unsaturated cyclic fatty acids of animals that are formed as cyclooxygenase metabolites especially from unsaturated fatty acids (as arachidonic acid) composed of a chain of 20 carbon atoms and that perform a variety of hormonelike actions (as in controlling blood pressure or smooth muscle contraction)

91
Q

pyruvate carboxylase

A

pyruvate —> Oxaloacetate. Requires **Biotin!!!

92
Q

Single electron (e-) transfers to oxygen generate three reactive oxygen species (ROS)

A

superoxide, hydrogen peroxide, and hydroxyl radical

93
Q

NADH dehydrogenase (Complex I)

A

Requires FMN and Fe-S. 4 H+ per NADH. Feeds into CoQ

94
Q

succinate dehydrogenase (Comlex II)

A

Part of CAC. Converts succinate to fumarate. Reduces FAD to FAD2H. Feeds e- to CoQ. Not a transmembrane enzyme; pumps NO H+

95
Q

cytochrome b-c1 complex (Complex III)

A

Pumps 4 H+ for each CoQH2(red). Feeds e- to cytochrome C. Has *heme group

96
Q

cytochrome c oxidase (Complex IV)

A

Has *heme, *copper, *zinc, which pass electrons to O2. Pumps 2H+ for eacy Cytochrome C(red)

97
Q

Cytochrome c

A

has *heme group

98
Q

UCP1

A

uncoupling protein 1 (aka thermogenin). Dissapates H+ gradient accross inner mito membrane. This allows fat to be utilized for heat independently of ATP consumption

99
Q

The effects of PDH deficiency are primarily neurological, affecting brain development. Why?

A

Brain can not utilize fatty acids, and needs glucose for fuel.

100
Q

Hereditary or acquired PDH deficiency can result in lactic acidosis (a.k.a. lacticacidemia). Why?

A

pyruvate cannot get converted to acetyl CoA, so pyruvate is converted to lactate + **H+

101
Q

Nitrogen balance equation

A

Nitrogen (g) = nitrogen intake (g) - urinary urea nitrogen (g) - X (g) **0.16g Nitrogen/gram protein

102
Q

Symptoms of ammonia toxicity

A

lethargy, headache, seizure, etc. Neuronal cells are particularly vulnerable to the toxicity of ammonia.

103
Q

proteases

A

cut peptide bonds found in protein

104
Q

Transport of amino acids from the gut lumen into intestinal epithelial cells is by ______________

A

secondary active transport–requires energy. Active transport of Na+ into intestinal lumen, then Na+ and amino acid symport into intestinal cell.

105
Q

Glutamate: what is formed through deamination? what role does this play?

A

intracellular: a-ketoglutarate The amino group pool of the cell

106
Q

In fed state: what happens to dietary aa?

A

insulin promotes storage pathways (in the case of aa, they are stored in protein through translation). Liver is responsible for

107
Q

In fasted state: Nitrogen leaves muscle cell as either _____ and ______

A

glutamine and alanine

108
Q

Production of urea occurs in the _______

A

Liver

109
Q

Fasted state: what are the three hormones that promote the mobilization of stored fuels?

A

Glucagon, cortisol, epinephrine and norepinephrine

110
Q

Glutamate donates the amine group to…

A

pyruvate, forming alanine. Alanine is transported to the liver. *fasted state

111
Q

a-ketoglutarate (a-KG) acts as the _______, forming ________

A

universal amine acceptor, forming glutamate. In *fasted state

112
Q

Alanine’s carbon is used for ___________, and the nitrogen is converted to ____for excretion.

A

gluconeogenesis; urea

113
Q

______________ and ____________ can add free ammonium to “fix” it as glutamine. These reactions require energy.

A

Glutamate dehydrogenase and glutamine synthase

114
Q

glutamate dehydrogenase

A

glutamate—–> a-ketoglutarate (NAD(P)+ –> NAD(P)H). This is a deamination rxn. This is *reversable

115
Q

glutamine synthetase

A

Glutamate + ATP + NH3 → Glutamine + ADP + phosphate

116
Q

The urea cycle occurs in the _____

A

Liver

117
Q

hepatic encephalopothy

A

is the occurrence of confusion, altered level of consciousness, and coma as a result of liver failur

118
Q

carbamoyl phosphate synthetase I (CPS I)

A

**fixes free ammonia. takes carbonate and ammonia —> carbamoyl phosphate (requires 2 ATP) occurs in mito!

119
Q

ornithine transcarbamoylase

A

takes ornithine —-> citrulline; this can leave mito and enter cytosol

120
Q

arginine and the urea cycle

A

increases synthesis of N-acetyl-glutamate (NAG) by N-acetyl-glutamate synthase. NAG acts as an allosteric activator of carbamoyl phosphate synthetase I.

121
Q

4 things than can cross the inner mitochondrial membrane

A

NH3, O2, H2O, CO2

122
Q

Arginine is a major regulator of the urea cycle. When arginine builds up. . .

A
  1. It increases the synthesis of N-acetyl-glutamate (NAG). NAG allosterically activates CPS-I. 2. It increases arginase activity
123
Q

Elevated urinary orotic acid is characteristic of

A

urea cycle disorders downstream of CPS-I.

124
Q

If there is a defect in CPS I, will we see high or low [orotic acid]?

A

low. b/c CPSI produces carbamoyl phosphate, which is precursor to orotic acid

125
Q

defect in the ornithine / citrulline antiporter causes what?

A

HHH syndrome (hyperamonia … …). Increase in orithine

126
Q

Measuring free ammonium and blood urea nitrogen (BUN)

A

incubate blood with recombinant GDH

127
Q

The goal of hyperammonia treatment: Decrease blood [NH4+]. How?

A

Low protein diet; N-carbamoylglutamic acid; Eliminate nitrogen in alternative pathways: Arginine, Benzoic acid, Phenylbutyrate

128
Q

How do phenylbuterate and benzoic acid work as a treatment for disorders of the urea cycle?

A

They are used to make amino acids more excretable

129
Q

Arginine can be used as a treatment for inherited disorders of the urea cycle. How does it work? regenerate ornithine in the case of arginosuccinate lyase deficiency.

A

regenerate ornithine in the case of arginosuccinate lyase deficiency. arginosuccinate in urine (mildly excreatable)

130
Q

N-carbamoyl-glutamate can be used as a treatmenf for inherited disorders of the urea cycle. How does it work?

A

N-carbamoyl-glutamate is an analog of N-acetyl-glutamate. It can be used to treat NAG synthase deficiency.

131
Q

arginosuccinate lyase deficiency blocks what step in the urea cycle

A

the conversion of arginionsuccinate to arginine. Would expect to see increased argininosuccinate and citruline. Low arginine and ornithine, and uria

132
Q

Detoxification mostly occurs where

A

Smooth ER, (some RER)

133
Q

Formation of ____ and ____ coated vesicles involves GTP-binding proteins

A

COPI and COPII

134
Q

ca++ is important for SER

A

ER membranes possess Ca++ transporters that actively transport Ca++ into ER lumen. This is important for muscle contraction.

135
Q

Formation of membrane vesicles usually involves specific coat proteins. COPII coats

A

COPII mediates ER-to-Golgi transport,

136
Q

Formation of membrane vesicles usually involves specific coat proteins. COP I coats

A

COPI mediates intra-Golgi and Golgi-to-ER transport

137
Q

Familial hypercholesterolemia (FH): an example of a specific deficit in an endocytic pathway

A

Normal LDL particles *are normally taken up and processed by hepatocytes via receptor-mediated endocytosis. In FH, LDL particles are produced and released by the liver; taken up by all cells.

138
Q

IRE1, PERK, ATF6

A

kinase, that phosphorelates itself and can recognize misolfed protein in ER

139
Q

Ceremide is made in _____

A

ER, transported to Golgi and used to make glycolipids and sphingomyelin

140
Q

function of chaperones

A

help proteins fold correctly (present in both cytoplasm and ER).

141
Q

Proteosomes

A

misfolded proteins are ubiquinated (taged) and destroyed in the proteosome

142
Q

retrotranslocation and missfolded proteins

A

misfolded proteins in the ER are translocated to the cytoplasm, taged by ubinquitin and degraded in proteosome

143
Q

N-linkage

A

A 14-sugar oligosaccharide is first assembled on a membrane lipid called dolichol, and subsequently transferred to an *asparginine on the polypeptide chain as it spools into the ER lumen.

144
Q

O-linkage

A

Few cytoplasmic proteins (made by free ribosomes) are glycosylated (*O(serine or threinine)-linked with small oligosaccharide chains).

145
Q

sugar groups of glycoproteins are always located on the________side of membranes.

A

non-cytosolic (ER lumin)

146
Q

Proteoglycans

A

class of very heavily glycosylated proteins. The protein core of a proteoglycan is made in the ER, but glycosylation (via an O-linkage) occurs either in the Golgi or cytosol. The sugars are usually sulfated and negatively charged, which attract cations and water, leading to the **formation of hydrated gels.

147
Q

cis face of the Golgi

A

receives product from the ER in the form of membrane bound vesicles. mannose-6-phosphate (M6P) ‘tag’ is added to lysosomal acid hydrolases

148
Q

trans face of the Golgi

A

is associated with clathrine and receptors for M6P concentrate lysosomal enzymes into vesicles, which bud off of the Golgi and fuse with early endosomes.

149
Q

Formation of COPI and COPII coated vesicles involves GTP-binding proteins

A
  1. GEF catylizes Sar1-GDP —> Sar1-GTP 2. Sar1-GTP recruits adaptor proteins, and cargo receptor proteins which concentrates the cargo and begins to curve the membrane. 3. Sec13/31 is then recruited, which forms a cage-like structure, helping the vesicle to further form and pinch off.
150
Q

insulin activates ________

A

phosphatases

151
Q

insulinoma

A

are islet-cell tumors of the pancreas that excrete insulin, leading to hypoglycemia. Diagnostics: plasma glucose, insulin, C-peptide.

152
Q

N-acetylglutamate synthase

A

an enzyme that catalyses the production of N-acetylglutamate from acetyl-CoA and glutamate

153
Q

N-carbamoyl-glutamate

A

is an analog of N-acetyl-glutamate. It can be used to treat NAG synthase deficiency.

154
Q

blood urea nitrogen (BUN) test

A

measure free ammonia in a patient, incubate their blood with recombinant GDH, a-ketoglutarate, and NADPH (reduced). NADPH absorbs UV light, so absorption decreases as it is oxidized. The decrease in light absorption is proportional to the concentration of NH4+

155
Q

HHH syndrome

A

In hyperammonaemia, hyperornithaemia, homocitrullinaemia syndrome (HHH syndrome), the ornithine / citrulline antiporter is defective.

156
Q

Where does NH4+ come from in the mito for its inclusion in the urea cycle

A

from deamination of amino acids, e.g. glutaminase or glutamate dehydrogenase

157
Q

Transcytosis

A

movement of material through cells, from one side to another

Foundations (5 decks)

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