Carbohydrate Metabolism Flashcards
(146 cards)
1
Q
What is associated with deficiency of hexokinase?
A
Maturity onset diabetes of the youth
2
Q
What converts fructose-6-phosphate in glycolysis?
A
Phosphofructokinase-2 and 1 (PFK) converts F6P to fructose-2,6-bisphosphate and fructose-1,6,bisphosphate, respectively
3
Q
How does fructose-2,6-bisphosphate induce glycolysis?
A
By upregulating PFK-1
Citrate and ATP inhibit PFK-1
4
Q
What endocrine signal upregulates PFK-2?
A
Insulin
PFK-2 converts F6P to F-2,6-bP
5
Q
Glucagon decreases the concentration of ______
Glycolytic enzyme
A
F-2,6-bP, increasing activity of fructose-1,6-bisphophatase
Halts hepatic glycolysis and results in gluconeogensis
6
Q
Decreased pyruvate kinase activity in RBCs
A
Equals decreased ATP, and hemolysis
Decreases the cells ability to pump cations against a concentration gradient
7
Q
TCA cycle
A
8
Q
What inhibits the first step of TCA cycle?
A
ATP inhibits citrate synthase
9
Q
Elevated conc. of citrate blocks ______ ?
A
PFK-1 of glycolysis
Activates acteyl-coA-carboxylase of fatty acid synthesis
10
Q
Isocitrate DH
A
Rate-limiting step
Requires Niacin
Produces CO2/NADH/alpha-ketoglutarate
Inhibited by ATP and NADH
Activated by ADP
11
Q
Cofactors involved in alpha-ketoglutarate DH activity
A
Thiamine (B1)
Lipoic acid
CoA (B5, pantothenic acid)
FAD (vitamin B2, riboflavin)
NAD (B3, niacin)
“TLC for Nancy”
12
Q
alpha-ketoglutarate DH
A
Converts alpha-ketoglutarate to succinyl-CoA
Produces NADH and CO2
Inhibited by ATP/NADH/Succinyl-CoA
Activated by Ca2+ in skeletal muscle
13
Q
Wernicke-Korsakoff syndrome
A
Thiamine (B1) deficiency
sxs: ataxia, opthalmoglegia, and memory loss
14
Q
Disorders related to thiamine deficiency
A
Dry-Beriberi
Wet-Berberi
Wernicke-Korsakoff
15
Q
TCA cycle enzymes that require niacin (B3)
A
Isocitrate DH
alpha-ketoglutarate DH
Malate DH
NAD+ -> NADH (part of each of the above enzymatic processes)
16
Q
What TCA cycle enzymes require riboflavin (B2)
A
alpha-ketoglutarate DH
Succinate DH (FADH2 to and from FAD)
17
Q
What is complex II of the ETC?
A
Succinate DH
Also part of TCA cycle
18
Q
Where does beta-oxidation and TCA cycle take place?
A
The mitochondria
19
Q
The malate-aspartate shuttle
A
20
Q
Reduction potential of the ETC complexes and carriers
A
21
Q
When one oxygen molecule accepts electrons from the ETC, how many water molecules are produced?
A
Two H2O
22
Q
How many total protons are pumped across the inner mitochondrial matrix when NADH+H+ reacts to with complex I to form NAD+?
A
Ten total H+’s are pumped
4 four complex I
2 from Q
2 from complex III
2 from complex IV
Becuase FADH2 reacts at complex II (which itself does not pump protons) only six protons are transferred as result
23
Q
How many protons must transfer back through ATPase to generate one ATP?
A
Just over three protons
24
Q
ATP equivalents of high-energy electron carriers produced by other metabolism?
Other than ETC
A
25
What toxic molecules bind to complex IV and prevent the reduction of O2 to H2O?
HCN/CO/N3
26
Biguanide
Metformin - selectively inhibits complex I of the ETC, leading to increased levels of ADP and AMP (AMP inhibits adenyl cyclase which produces cAMP)
## Footnote
cAMP inhibits adenyl cyclase - inhibiting gluconeogenesis and lowering blood glucose levels (acts as a glucagon antagonist)
27
Answer: B. Decreased ATP production in erythrocytes
Rationale: **Pyruvate kinase deficiency** results in reduced ATP production in erythrocytes. This leads to inadequate energy for maintaining the membrane cytoskeleton, resulting in hemolytic anemia. The characteristic spiculated red cells (echinocytes) are a result of this membrane instability.
28
Answer: C. Jejunoileal bypass surgery
Rationale: D-lactic acidosis is an unusual form of lactic acidosis caused by the accumulation of D-lactic acid in the colon due to **bacterial carbohydrate metabolism**. This condition is observed in patients with jejunoileal bypass or intestinal resection, which alters the gut microbiome and carbohydrate metabolism.
29
Answer: B. Inhibits phosphofructokinase-1
Rationale: Citrate is an **allosteric inhibitor of phosphofructokinase-1** (PFK-1), a key regulatory enzyme in glycolysis. High levels of citrate indicate an abundance of biosynthetic precursors and energy, signaling a reduced need for glycolysis.
30
Answer: A. Decreased NADH oxidation in mitochondria
Rationale: The malate-aspartate shuttle is crucial for transferring reducing equivalents (electrons) from cytosolic NADH into the mitochondria. A defect in this shuttle would result in decreased NADH oxidation in mitochondria, leading to reduced ATP production through oxidative phosphorylation.
31
Answer: C. Glucokinase is primarily found in the liver
Rationale: Glucokinase (hexokinase IV) is primarily found in liver cells and has different kinetic properties compared to other hexokinase isoforms. It has a higher KM (lower affinity) for glucose, allowing it to respond to higher glucose concentrations and regulate glucose metabolism in the liver
32
Answer: C. Oxidative phosphorylation
Rationale: Leigh syndrome is a mitochondrial disorder characterized by progressive loss of mental and movement abilities. It typically results from mutations affecting oxidative phosphorylation, either in mitochondrial DNA or nuclear DNA encoding mitochondrial proteins
33
Answer: C. Inhibition of ATP synthase
Rationale: Oligomycin is an **inhibitor of the F0 portion of ATP synthase**. It blocks the channel through which protons flow back into the mitochondrial matrix, thereby inhibiting ATP synthesis. This leads to a buildup of the proton gradient and a decrease in ATP production through oxidative phosphorylation.
34
Answer: C. Used to reduce pyruvate to lactate
Rationale: In erythrocytes, which **lack mitochondria**, the NADH produced during glycolysis cannot be oxidized via the electron transport chain. Instead, it is used to reduce pyruvate to lactate via the enzyme **lactate dehydrogenase**. This regenerates NAD+ to allow glycolysis to continue, providing ATP for the erythrocyte
35
Answer: A. Decreased conversion of pyruvate to acetyl-CoA
Rationale: The pyruvate dehydrogenase (PDH) complex catalyzes the conversion of pyruvate to acetyl-CoA, which is the **first committed step in aerobic metabolism**. A mutation in this complex would lead to decreased conversion of pyruvate to acetyl-CoA, resulting in pyruvate accumulation and lactic acidosis.
36
Answer: B. Phosphofructokinase-1
Rationale: Phosphofructokinase-1 (PFK-1) is the **main control point for glycolysis**. Cancer cells often exhibit increased glycolysis rates (Warburg effect), and upregulation of PFK-1 would promote increased glucose utilization.
37
Answer: C. Decreased activity of pyruvate dehydrogenase complex
Rationale: **Thiamine diphosphate is an essential coenzyme for the pyruvate dehydrogenase complex**. Thiamine deficiency results in decreased PDH activity, leading to impaired pyruvate utilization and neurological symptoms due to inadequate energy production in neural tissues.
38
Answer: C. Increased glycolysis in cancer cells
Rationale: Cancer cells exhibit significantly increased rates of glycolysis, **even in the presence of oxygen (Warburg effect).** PET scans use radioactive glucose analogs, which accumulate in tissues with high glucose uptake and metabolism, making them effective for detecting cancer cells.
39
Answer: C. Inhibition of pyruvate dehydrogenase complex
Rationale: Arsenic poisoning results in the inactivation of the pyruvate dehydrogenase (PDH) complex due to **irreversible binding of arsenates to the sulfhydryl groups of lipoic acid**, a crucial component of the PDH complex. This inhibition blocks energy production through aerobic carbohydrate metabolism.
40
Answer: D. Activates phosphofructokinase-1
Rationale: AMP serves as an important **allosteric activator of phosphofructokinase-1 (PFK-1)**. It is a more sensitive indicator of ATP consumption than ADP and effectively activates PFK-1 to increase glycolysis when energy levels are low
41
Answer: B. Decreased proton gradient across the inner mitochondrial membrane
Rationale: Complex III is crucial for electron transport and proton pumping across the inner mitochondrial membrane. A defect in Complex III would lead to a decreased proton gradient, impairing ATP production through oxidative phosphorylation.
42
Answer: B. Decrease proton gradient
Rationale: Uncoupling proteins, particularly UCP1 in brown adipose tissue, allow protons to leak across the inner mitochondrial membrane. This decreases the proton gradient, uncoupling electron transport from ATP production and dissipating energy as heat, a process important for thermogenesis.
43
Answer: C. Electron transport chain
Rationale: LHON is a mitochondrial disorder caused by mutations in mitochondrial DNA. These mutations typically affect **complex I** of the electron transport chain, leading to impaired oxidative phosphorylation and energy production, particularly affecting high-energy demand tissues like the optic nerve.
44
Answer: C. Glucokinase is primarily found in the liver
Rationale: Glucokinase (hexokinase IV) is primarily found in liver cells and has different kinetic properties compared to other hexokinase isoforms. It has a higher KM (lower affinity) for glucose, allowing it to respond to higher glucose concentrations and regulate glucose metabolism in the liver.
45
Answer: B. Activates α-ketoglutarate dehydrogenase
Rationale: ADP serves as an activator of several enzymes in the citric acid cycle, including α-ketoglutarate dehydrogenase. High levels of ADP indicate a need for increased energy production, stimulating the cycle to generate more reducing equivalents for ATP synthesis.
46
Kinetics of glucokinase vs. hexokinase
Hexokinase remains highly active even when glucose levels are low, ensuring the viability of glucose-dependent tissues.
Glukokinase allows rapid conversion to G6P when blood glucose is high, buffering blood glucose levels
47
Possible fates of G6P
Conversion to pyruvate (glycolysis)
Conversion to ribose-phosphate (pentoses, hexose monophosphate pathway)
Conversion to glycogen
Conversion to glucose (only in the liver, kidney, and intestines)
48
Synthesis of 2,3-bisphosphoglygerate
In erythrocytes, 1,3 BPG is converted to 2,3 BPG by BPG mutase.
49
Possible fate of pyruvate
50
Lactate DH - H isoform
Prominent in heart muscle
H isoform favors the conversion of lactate to pyruvate (found in lactate utilizing tissues such as the heart)
## Footnote
H4
Elevation of this form in serum indicates myocardial infarction since heart tissue damage releases this
51
Lactacte DH - M isoform
Prominent in skeletal muscle
The M isoform favors the conversion of pyruvate to lactate
## Footnote
M4 predominate form in skeletal muscle tissue
52
Under anaerobic conditions, _______ is produced
L-lactic acid
53
D-Lactic acidosis
Observed in patients with jejunoileal bypass or intestinal resection. Due to bacterial carbohydrate metabolism and accumulation of D-lactic acid in the colon.
54
Causes of lactic acidosis
Poor tissue oxygenation (inadequate circulation), diseased or compromised tissues (diabetes or malignancy) or drugs/toxins that interfere with oxidative metabolism.
55
Pyruvate kinase inhibition (liver isoform)
Inhibited by ATP, acetyl CoA, and fatty acids. Helps regulate energy utilization and the TCA cycle when energy stores are high and the cycle is slow.
56
PFK regulation
AMP is more sensitive allosteric activator than ADP - displaces ATP (allosteric inhibitor)
Citrate - another allosteric inhibitor
57
The TCA cycle represents the convergence of the metabolism of what macromolecules?
Carbohydrates/fats/proteins
58
Where is PDH?
Pyruvate DH complex is in the mitochondria (pyruvate has to be transported in from the cytosol)
59
PDH kinase
Phosphorylates PDH complex to deactivate it
## Footnote
PDH kinase activity is activated by ATP, NADH, and acetyl-CoA
Inhibited by ADP, NAD+, CoASH
60
PDH phosphatase
Removes phosphate from PDH complex, converting it into a more active form
61
The brain (and neural tissue in general) rely heavily on what for energy production?
The brain and neural tissue rely almost exclusively on glucose for energy production.
PDH complex dysfunction affects these tissues first
62
Beriberi
Thiamine deficiency - results in low rate of pyruvate utilization (ATP is inadequate).
Neurologic disorders, muscle weakness, and increased blood pyruvate levels.
Wet Beriberi - heart failure
63
Arsenic poisoning
Ingestion of arsenates results in the inactivation of PDH reactions due to irreversible binding of the sulfhydryl groups of lipoic acid (lipoamide). This blocks energy production through aerobic carbohydrate metabolism.
Because arsenic binds sulfhydryls of collagen in hair and nails, it can be detected in tissue samples.
sxs: nausea, vomiting, weakness, and dyspnea.
64
Genetic defects in the PDH complex
Cerebral lactic acidosis, encephalopathies, ataxia, and mental retardation.
Brain obtains almost all of its energy from aerobic oxidation of glucose
65
Regulated steps of TCA cycle
Citrate synthase
Isocitrate DH
Alpha-ketoglutarate DH
66
Citrate synthase
67
Isocitrate DH
68
Alpha-ketoglutarate DH
69
Succinate DH
## Footnote
AKA complex II of ETC
70
Malate DH
71
Substrate level phosphorylation in the TCA cycle
Succinyl CoA synthetase (GDP - GTP)
72
The conversion of FADH2 to FAD (and vice versa) requires what coenzyme?
Riboflavin (B2)
73
Net reaction of TCA cycle
74
TCA cycle's role in lipid synthesis
Acetyl-CoA is the primary source of carbons for fatty acids and cholesterol.
Citrate also serves as a source of acetyl-CoA.
Acetyl-CoA cannot pass across the inner mitochondrial membrane, and citrate serves as mechanism to transport acetyl-CoA out of the mitochondria, where it is metabolized using the enzyme **ATP citrate lyase**.
75
What can be used as a source of glucose through gluconeogenesis?
| From TCA cycle
Malate and oxaloacetate
76
What TCA cycle intermediates can be converted to AA's?
Oxaloacetate -> aspartate
alpha-ketoglutarate -> glutamate
## Footnote
Through transamination reactions
77
Succinyl-CoA is a precursor for the heme group of ______
Porphyrin
78
Pyruvate carboxylase
Allosterically activated by acetyl-CoA
Carboxylates pyruvate to form oxaloacetate, requiring the expenditure of one ATP
Biotin (B7) is an essential component of pyruvate carboxylase and serves as a carrier of the carboxyl group (CO2)
79
What hormones regulate the TCA cycle?
The TCA cycle is not directly regulates by hormones.
Instead, the rate of the cycle is controlled by substrate availability and allosteric regulation of enzyme activity.
The PDH complex is a major control point of the TCA cycle
TCA flux can also be regulated by the citrate synthase rx'n, du to reduced availability of oxaloacetate (substrate availability)
Increased NAD+/NADH ratio activates TCA cycle DH's
80
Major metabolic controls of TCA cycle
81
What mitochondrially membrane is most selectively permeable?
The inner membrane, the outer membrane contains porins
82
Galactose metabolism
83
Primary vs. secondary lactose intolerance
Secondary - acquired (damage to small intestines - crohn's disease, ulcerative colitis...etc.)
84
How does the increased formation of galactitol impact the eyes?
Can result in the formation of cataracts
85
Galactokinase deficiency
Deficiency - buildup of galacticol and can result in infantile cataracts
86
What converts galactose-1-phosphate to glucose-1-phosphate?
Galactose-1-phosphate uridyltransferase
## Footnote
Deficiency - **classic galactosemia**
galactose-1-phosphate is toxic - builup in liver - damage
Also, cataracts
Susceptible to sepsis with E. coli infections
87
Fructose metabolism
Underline - where enters glycolysis
88
What enzyme traps fructose inside of the cell?
Fructokinase converts fructose into fructose-1-phosphate
89
How do people with fructokinase deficiency still metabolize fructose?
Hexokinase converts fructose to fructose-6-phosphate (glycolytic intermediate)
90
Essential fructosuria
Accumulation of fructose in blood and urine
## Footnote
Detected by copper reduction test (any reducing sugar)
91
Hereditary fructose intolerance
Dysfunction of aldolase-B
More serious than essential fructuria - fructose-1-phosphate is trapped in the cell
92
Deficiency of the enzyme aldolase-B - ATP is wasted by producing fructose-1-phosphate (cannot be utilized)
*New food
93
Polyol pathway
Increased levels of sorbitol (due to hyperglycemia) - osmotic damage - cataracts
94
ETC inhibitors/disruptors
Rotenone is more important than amytal
95
Pentose phosphate pathway
Aka hexose monophosphate shunt
96
Where are the enzymes of the PPP located?
Cytoplasm of tissues where there are high levels of fatty acid biosynthesis and steroid biosynthesis (both use large amounts of NADPH)
## Footnote
Liver/Adipose/Adrenal Cortex/Testis/lactating mammary glands
97
What do erythrocytes use to reduce glutathionine, how is this reducing agent made?
NADPH is synthesized in RBC's via the HMP shunt
98
PPP - oxidative pathway
99
PPP - Non-oxidative pathway
## Footnote
Transketolase - key enzyme in non-oxidative branch (requires thiamine pyrophosphate - TPP)
100
When is the combined activity of the oxidative/non-oxidative branches of HMP shunt utilized?
When NADPH generation is needed but ribose is not
## Footnote
Tissues where fatty acid synthesis is active
Ribose-phosphates generated from oxidative branch can be converted to glycolytic intermediates through the nonoxidative branch rx'ns
101
High ratio of NADP+/NADPH
##Footnote
Effect on dehydrogenase enzymes
Increases activity of DH enzymes
102
G6PD Deficiency (pattern of inheritance)
**X - chromosome (x-linked recessive)**
More frequently expressed in males (one copy of the x chromosome)
103
Pyruvate DH complex
104
Rotenone (Amytal is stronger inhibitor = sicker Pt)
105
A researcher is studying the role of proteins in the inner mitochondrial membrane. She identifies a protein that allows protons to leak across the membrane, leading to heat production without ATP generation. What class of proteins is she most likely studying?
Uncoupling proteins
106
A 28-year-old male presents with sudden central vision loss. His family history reveals that his maternal grandfather and uncle had similar symptoms in their 20s. Which mitochondrial diseases is most likely responsible for the patient's condition?
Leber hereditary optic neuropathy (**LHON**) is often characterized by bilateral, painless subacute loss of central vision most commonly during young adult life. In most cases, symptoms begin with one eye first, followed a few weeks later by visual failure in the other eye.
107
Which enzyme is responsible for the conversion of glucose to sorbitol in the polyol pathway?
Aldose reductase
108
Which disorder is characterized by nausea, vomiting, and hypoglycemia after ingestion of fructose?
Hereditary fructose intolerance
109
Which enzyme deficiencis associated with "Classical galactosemia"?
Galactose-1-P uridytransferase
110
Which enzyme is crucial for the maintenance of reduced glutathione in the cell?
Glutathione reductase
111
G6PD deficiency primarily affects which cell type, leading to increased sensitivity to oxidative stress?
Erythrocytes
112
Which of the following conditions is characterized by the presence of fructose in the urine?
Essential fructosuria
113
A researcher is studying the regulation of blood glucose levels. She administers a compound that inhibits the conversion of oxaloacetate to phosphoenolpyruvate. Which pathway is she most likely targeting?
Gluconeogenesis
114
A patient presents with symptoms of hypoglycemia. Laboratory tests reveal a deficiency in an enzyme that catalyzes the conversion of fructose-1,6-bisphosphate to fructose-6-phosphate. Which of the following pathways is most likely impaired in this patient?
Gluconeogenesis
115
A researcher is studying the effects of a new drug on glucose metabolism. She observes that the drug inhibits the action of a hormone that decreases the conversion of glucose to pyruvate in the liver. Which hormone's action is most likely being inhibited by the drug?
Glucagon
116
Classical galactesemia
117
Glycogen
It is a very large, branched polymer of α(1→4) glucose residues with α(1→6) branches every 8‐10 residues. Glycogen can be broken down to yield glucose molecules when energy is needed.
118
Why can't glycogen in **muscle** be converted to free glucose?
Muscle lacks glucose-6-phosphatase
119
Glycogen phosphorylase
Hydrolyzes residues from the nonreducing ends through phosphorolysis. The enzyme will not cleave beyond four residues from a branch.
Active when phosphorylated (muscle)
120
Glucan transferase
A debranching enzyme. Glucan transferase moves three residues from a branch to the main chain.
121
α(1→6) glucosidase
aka **debranching enzyme**
Another debranching enzymes. α(1→6) glucosidase removes the remaining glucose residue (steps two and three are two activities of the same enzyme)
122
What organs contain the enzyme glucose-6-phosphatase
The liver and kidneys
123
Why doens't glucose-6-phosphatase interfere with glycolysis?
Glucose-6-phosphatase can only be found within the ER of liver/kidney cells
124
What transporter facilitates glucose leaving the cell?
GLUT2
125
Glycogen synthase
Adds UDP-glucose to the non-reducing ends of glycogen particles
Active when dephosphorylated (muscle)
126
Glycogenin
Protein that serves as primer for glycogen synthesis. Catalyzes the transfer of a glucose from UDP-glucose to the hydroxyl group of a Tyr residue on the protein. The chain is extended, eventually becoming a substrate for glycogen.
## Footnote
Glycogenin remains buried in the core of the glycogen molecule
127
What activates glycogen phosphorylase (molecular level)?
The addition of a phosphate, added by glycogen phosphorylase kinase.
128
Glycogen metabolic regulation
Primarily by hormones - insulin, glucagon, epinephrine
In skeletal muscle - allosterically (ATP, AMP, Ca2+)
129
Difference in glycogen regulation between glycogen found in liver and muscle
Muscle - hormonal regulation is through epinephrine instead of glucagon (Epi causes and increase in cAMP and affects enzymes similar to glucagon in the liver)
Glycogen phosphorylase can be directly activated by AMP
Calcium activates glycogen phosphorylase kinase. One of the subunits is calmodulin, a calcium-binding protein. Calcium stimulates the acctivation of glycogen phosphorylase and glycogen breakdown during contraction.
130
Comparison of glycogen metabolism in muscle vs liver
131
Liver glycogen storage disease
Result in hepatomegaly and hypoglycemia, or cirrhosis
132
Muscle glycogen storage disease
Result in skeletal and cardiac myopathies and/or energy impairment.
## Footnote
McArdle disease - glycogen phosphrylase impaired
133
Von Gierke (type I) disease
Due to a deficiency in glucose-6-phosphatase, which is needed for the release of glucose produced from either gluconeogenesis or glycogen. Results in severe fasting hypoglycemia. It causes hepatomegaly due to the accumulation of glycogen stores in the kidney and liver.
134
Pompe's disease (type II)
Due to a defect in a lysosomal enzyme, lysosomal acid glucosidase, that is responsible for the turnover of glycogen particles. It acts similarly to maltase in the digestive tract but functions in lysosomes and is sometimes referred to as acid maltase.
**It results in severe cardiac and skeletal muscle myopathy.**
135
Cori's disease
Due to a loss of the debranching enzyme and results in glycogen accumulation in muscle and fasting hypoglycemia.
136
McArdle disease
Due to a deficiency in muscle glycogen phosphorylase. Primary sx is cramping, muscle pain, and myoglobinuria following exercise.
137
Defect in glycogen synthesis
| Name and describe disease
**Anderson's disease** - due to defect in the branching enzyme of glycogen synthesis and results in very long, unbranched glucose chains being stored in glycogen. The long unbranched molecules have a low solubility which leads to glycogen precipitation and deposits that build up in body tissue.
138
Metabolism of alcohol
| Pathway
139
Alcohol DH
| Methanol substrate
Produces formaldehyde and ehtylene glycol to ultimately yield glycolic and oxalic acids
140
Acetaldehyde DH
Converts acetaldehyde to acetate, which is converted to acetyl-CoA by acetyl-CoA synthase
141
Elevated NADH and depleted NAD+
Leads to the inhibition of gluconeogenesis (Can lead to hypoglycemia, esp in malnourished)
Inhibition of TCA cycle
Inhibition of lactate DH (shifts in metabolism of glucose toward lactate) - can lead to lactic acidosis (slowed E production can lead to hypothermia)
142
Fatty liver
Aka hepatic steatosis - caused by the altered NADH/NAD+ of exess alcohol intake.
Inhibits gluconeogenesis
Inhibits fatty acid oxidation
Inhibits TCA
## Footnote
Each of these inhibited pathways results in the diversion of acetyl-CoA into de novo fatty acide synthesis.
143
Fetal alcohol syndrome
Most common nonheritable cause of intellectual disability.
Dx: Pre/postnatal growth retardation, facial dysmorphology, CNS dysfunction, neurobehavioral disabilities
EtOH crosses placenta, rapidly reaching the fetus (depends on maternal hepatic detox - disrupts DNA/protein syn.
144
A 2-month-old infant presents with severe cardiomyopathy, hypotonia, and hepatomegaly. Genetic testing reveals a deficiency in lysosomal acid glucosidase. Which of the following best explains the systemic nature of this patient's symptoms?
A. Impaired glycogen synthesis in multiple tissues
B. Enhanced glycogenolysis leading to hypoglycemia
C. Defective glucose transport in cardiac and skeletal muscle
D. Increased production of G6P
E. Accumulation of glycogen in lysosomes across various cell types
E. Accumulation of glycogen in lysosomes across various cell types
145
The activity of what enzyme is upregulated in Pt's w/ essential fructosuria?
Patients with essential fructosuria have fructokinase deficiency and thus cannot convert fructose to fructose-1-phosphate. Hexokinase (found in adipocytes and myocytes) becomes the primary enzyme responsible for fructose metabolism and converts it to fructose-6-phosphate, which can be used for glycolysis or converted to glucose-6-phosphate by glucose-6-phosphate isomerase. Fructose that is not converted by hexokinase is excreted in urine, which leads to the presence of reducing substances.
## Footnote
AMBOSS
146
What vitamin is a component of CoA?
Pantothenic acid (B5)
