Biochemistry- Metabolism Flashcards
What metabolic functions occur in the mitochondria?
fatty acid oxidation (beta-oxidation)
acetyl-CoA production
TCA cycle
oxidative phosphorylation
What metabolic functions occur in the cytoplasm?
glycolysis fatty acid synthesis cholesterol synthesis steroid synthesis (SER) protein synthesis (RER) HMP shunt
What metabolic functions occur in both the cytoplasm and mitochondria?
Heme synthesis
Gluconeogenesis
Urea cycle
What is the function of a kinase?
Uses ATP to add a phosphate group onto a substrate
What is the function of a phosphorylase?
Adds a phosphate group onto a substrate WITHOUT using ATP
What is the function of a phosphatase?
Removes a phosphate group
What is the function of a dehydrogenase?
catalyzes oxidation-reduction reactions
What is the function of a hydroxylase?
adds a hydroxyl group onto a substrate
What is the function of a carboxylase?
transfers CO2 groups with the help of biotin
What is the function of a mutate?
relocates a functional group within a molecule
How many ATP does aerobic glycolysis produce?
32
How many ATP does anaerobic glycolysis produce?
2
How many ATP does arsenic cause glycolysis to produce?
0
What type of processes is NAD+ generally used in?
catabolic processes
What type of processes is NADPH generally used in?
anabolic processes (steroid and fatty acid synthesis)
NADPH is also used in what other functions of the cell?
anabolic processes
respiratory burst
cytochrome P-450 system
glutathione reductase
Where is hexokinase located and what are some characteristics about the enzyme?
Most tissues
higher affinity (lower Km)
higher capacity (lower Vmax)
NOT induced by insulin
Feedback-inhibited by glucose-6-phosphate
NO gene mutation assoc. w/ maturity-onset diabetes of the young (MODY)
Where is glucokinase located and what are some characteristics about the enzyme?
Liver, beta-cells of pancreas
lower affinity (higher Km)
lower capacity (higher Vmax)
Induced by insulin
Feedback is NOT induced by glucose-6-phosphate
Gene mutation associated with maturity-onset of diabetes of the young (MODY)
How many ATP are produced through glycolysis?
2 ATP
FBPase-2 an PFK-2 are the same bifunctional enzyme who function is reversed by phosphorylation by what protein?
protein kinase A
What is the order of substrates in the TCA cycle?
Citrate Isocitrate alpha-ketoglutarate Succinyl-Coa Succinate Fumarate Malate Oxaloacetate
Citrate Is Kreb’s Starting Substrate For Making Oxaloacetate!
What are some electron transport inhibitors?
Rotenone (Complex I)
Cyanide (Complex IV)
Antimycin A (Complex III)
CO (Complex IV)
What is an ATP synthase inhibitor?
Oligomycin
What are some uncoupling agents?
2,4- dinitrophenol
aspirin
thermogenin in brown fat
What are the enzymes necessary for gluconeogenesis?
Pyruvate carboxylase
Phosphoenolpyruvate carboxykinase
Fructose-1,6-biphosphatase
Glucose-6-phosphatase
Pathway Produces Fresh Glucose
What organ does gluconeogenesis primarily occur in?
liver
What does propionyl-CoA form from?
odd chain fatty acids
Where in the TCA cycle can propionyl-CoA enter?
Succinyl-CoA
What are major products of the HMP shunt and what are these products used for in the body?
NADPH –> glutathione reduction inside RBCs, FA and cholesterol biosynthesis
Ribose –> nucleotide synthesis and glycolytic intermediates
Where does the HMP shunt occur?
lactating mammary glands
liver
adrenal cortex (sites for FA or steroid synthesis)
RBCs
What is the purpose of the respiratory burst (oxidative burst)?
Plays an important role in the immune response (both creation and neutralization with ROS)
What type of infections are patients with chronic granulomatous disease at an increase risk for and why?
Catalase + microorganisms because these organisms can neutralize their own H2O2
What is the most common human enzyme deficiency?
Glucose-6-phosphate dehydrogenase deficiency
What population is G6PD def. more common in?
African Americans
What can precipitate hemolytic anemia in individuals with G6PD deficiency?
fava beans sulfonamides primaquine anti-TB drugs infections
What type of inheritance is G6PD deficiency?
X-linked Recessive
What symptoms are seen with essential fructosuria? Is it a serious condition?
Fructose in the blood and urine
Benign condition
What inheritance pattern is seen in both essential fructosuria and fructose intolerance?
Autosomal recessive
What is the sequelae of fructose intolerance?
fructose-1-phosphate accumulates –> decrease in available phosphate –> inhibition of glycogenolysis and gluconeogenesis
What are symptoms of fructose intolerance?
hypoglycemia
jaundice
cirrhosis
vomiting
What is the treatment for fructose intolerance?
decrease intake of both fructose and sucrose
What substrate accumulates in galactokinase deficiency?
galactitol
What are symptoms of galactokinase deficiency?
galactose in blood and urine
infantile cataracts
may present as failure to track objects or to develop a social smile
What enzyme is deficient in classic galactosemia?
galactose-1-phosphate uridyltransferase
What are symptoms of classic galactosemia?
failure to thrive jaundice hepatomegaly infantile cataracts intellectual disability
What is the treatment for classic galactosemia?
exclude galactose and lactose (galactose + glucose) from the diet
What is the pathogenesis of diabetes symptoms due to sorbitol metabolism?
chronic hyperglycemia –> increase glucose converted to sortbitol –> increase sorbitol accumulation –> osmotic damage –> peripheral neuropathy, cataracts, and retinopathy
What are findings associated with lactase deficiency?
bloating, cramps, flatulence, and osmotic diarrhea
What is the treatment for lactase deficiency?
avoid dairy products
add lactase pills
What are the essential amino acids?
Phe Val Thr Trp Ile Met His Arg Leu Lys
PVT TIM HALL
What are the acidic amino acids?
Asp. and Glu
What are the basic amino acids?
Arg., Lys, and His
Which amino acids are increased in histones?
Arg and Lys
What is the function of the urea cycle?
Excess nitrogen (NH3) generated by amino acid metabolism is converted to urea to be excreted by the kidneys
What is the pneumonic to remember the order for the urea cycle?
Ordinarily, Careless Crappers Are Also Frivolous About Urination
What are causes of hyperammonemia?
acquired (liver disease)
hereditary (urea cycle enzyme deficiencies)
What condition is caused by N-acetylglutamate deficiency?
hyperammonemia
What finding would indicate an N-acetylglutamate deficiency vs. a carbamoyl phosphate synthase I deficiency?
increased ornithine with normal urea cycle enzymes suggests hereditary N-acetylglutamate deficiency
What is the amino acid derivative of NE and epi?
phenylalanine
What is the amino acid derivative of NAD+/NADP+?
tryptophan
What is the amino acid derivative of melatonin?
tryptophan
What is the amino acid derivative of histamine?
histidine
What is the amino acid derivative of heme?
glycine
What is the amino acid derivative of GABA and glutathione?
glutamate
What is the amino acid derivative of creatine, urea, and NO?
arginine
What disease is caused by a deficiency in phenylalanine hydroxyls?
PKU
What disease is caused by a deficiency in tyrosinase?
albinism
What disease is caused by a deficiency in homogentisate oxidase?
alkaptouria
What is the treatment for homocystinuria due to cystathione synthase deficiency?
decrease methionine
increase cysteine
increase B12 and folate in diet
What is the treatment for homocystinuria due to a decreased affinity of cystathione synthase for B6?
REALLY increase B6 in diet
increase cysteine in diet
What is the treatment for homocystinuria due to homocysteine methyltransferase deficiency?
increase methionine in diet
What are the findings for homocystinuria?
REALLY increased homocysteine in urine intellectual disability osteoporosis atherosclerosis tall stature kyphosis lens subluxation (down and inward) thrombosis
What is the cause of cystinuria?
defect in transport in PCT in kidney and intestinal cells
What amino acids or substrates does the defected transporter in cystinuria usually transport?
COLA
Cysteine
Ornithine
Lysine
Arginine
What test is diagnostic for cystinuria?
urinary cyanide-nitroprusside test
What mode of inheritance is cystinuria?
AR
What is the enzyme deficiency in Maple Syrup Urine Disease?
decrease in alpha-ketoacid dehydrogenase (B1)
What amino acids accumulate in Maple Syrup Urine Disease?
isoleucine
leucine
valine
What is the mode of inheritance for Maple Syrup Urine Disease?
AR
What are the physical findings in Maple Syrup Urine Disease?
severe intellectual disability
severe CNS defects
urine smells like maple syrup/burnt sugar
death
What is the treatment for Maple Syrup Urine Disease?
restrict leucine, isoleucine, and valine in diet
thiamine supplementation
What enzyme cleaves glucose - 1- phosphate residues off branched glycogen?
glycogen phosphorylase
What is the enzyme deficient in Von Gierke Disease (type I)?
glucose-6-phosphate
What is the treatment for Von Gierke Disease?
frequent oral glucose/cornstarch
avoidance of fructose and galactose
What is the enzyme deficient in Pompe Disease (type II)?
lysosomal alpha - 1, 4- glucosidase (acid maltase)
What are the findings in Pompe Disease?
cardiomyopathy and systemic findings leading to early death
hypotonia
What is the enzyme deficient in Cori Disease (type III)?
debranching enzyme (alpha-1,6-glucosidase)
What are the findings in Cori Disease?
milder form of type I (Von Gierke Disease) with NORMAL blood lactate levels
What is the enzyme deficiency in McArdle disease (type V)?
skeletal muscle glycogen phosphorylase
What are the findings in McArdle disease?
increased glycogen in muscle but cannot break it down –> MUSCLE CRAMPS, MYOGLOBINURIA, and ARRHYTHMIA (d/t electrolyte imbalances)
