A Usmle Biochem

Front 1

X-linked recessive
alpha galactosidase deficiency
ceramide trihexoside accumulation
renal failure
peripheral neuropathy hands/feet
CV disease

Back 1

Fabry's disease

Front 2

Autosomal recessive
Bgalactosidase def
galactocerebroside accumulation
optic atrophy
peripheral neuropathy/spasticity
developmental delay

Back 2

Krabbe's disease

Front 3

glucocerebrosidase def
glucocerebroside accumulation
hepatosplenomegaly
aseptic necrosis of femoral head
bone crises

Back 3

Gaucher's disease

Gaucher's cells (macrophages)

Front 4

Autosomal recessive
sphingomyelinase def
sphingomyelin accum in reticuloendothelial cells/parenchyma
leading to organomegaly and progressive neurodegeneration
cherry red spot on macula

Back 4

Niemann-Pick disease

No Man PICKs his nose w/ a SPHINGer

Front 5

Autosomal recessive
Absence of hexosaminidase A
GM2 ganglioside accumulation
death by age 3
cherry red spot on macula

Back 5

Tay-Sachs disease

Askenazi Jews (carriers = 1/30)

Front 6

Autosomal recessive
arylsulfatase A deficiency
demyelination with w/ ataxia, dementia
Cerebroside sulfate in brain, liver, kidney, PNS

Back 6

Metachromatic Leukodystrophy

Front 7

Autosomal recessive
alpha-L-iduronidase deficiency
corneal clouding
gargoylism
developmental delay

Back 7

Hurler's syndrome
Hurlers (shot put) do more damage than hunters (arrows)

Front 8

X-linked recessive
iduronate sulfatase deficiency
mild retardation
with aggressive behavior
no corneal clouding

Back 8

Hunter's syndrome

Front 9

Factors required for pyruvate dehydrogenase complex:

Back 9

B1 (Thiamine)
B2 (FAD)
B3 (NAD)
B5 (CoA)
Lipoic Acid

Front 10

buildup of pyruvate and alanine
reduced to lactate -> acidosis
seen in alcoholics in B1 deficiency
Rx: high fat/ketogenic nutrients

Back 10

Pyruvate Dehydrogenase Deficiency

Front 11

shuttles lactate from muscle to liver for regeneration to pyruvate
allows muscles to fxn anaerobically

Back 11

Cori cycle

Front 12

rate limiting enzyme of HMP shunt
necessary for RBCs to produce NADPH for GSH regeneration
loss leads to hemolytic anemia
triggered w/ oxidizing agents: sulfas, primaquine, fava beans
Heinz bodies - Hb precipitates
prevalent in Af-Am
X-linked recessive

Back 12

Glucose 6 Phosphate Dehydrogenase Deficiency

Front 13

aldolase B deficiency
all phosphate accum in F1P
inhib glycogenolysis/gluconeogenesis
hypoglycemia, jaundice, cirrhosis

Back 13

Fructose intolerance

Front 14

galactose-1P uridyltransferase def
accum of toxic metabolites
cataracts
hepatosplenomegaly
mental retardation

Back 14

Galactose intolerance

Front 15

How do you treat galactose intolerance?

Back 15

Decrease galactose and lactose

Front 16

How do you treat fructose intolerance?

Back 16

Decrease fructose and sucrose

Front 17

Name the 7 Phenylalanine derivatives:

Back 17

Tyrosine, Dopa, Dopamine, NE, Epinephrine, Melanin, Thyroxine

Front 18

Name the three tryptophan derivatives:

Back 18

Niacin (NAD, NADP)
Serotonin
Melatonin

Front 19

Glycine derivatives

Back 19

Porphyrin/Heme

Front 20

Arginine derivatives

Back 20

Creatine
Urea
Nitric Oxide

Front 21

defective cystathionine synthase or
defective methionine synthase
cysteine become essential
mental retardation
lens subluxation
osteoporosis
tall stature
kyphosis

Back 21

Homocystinuria

Front 22

alpha ketoacid dehydrogenase deficiency
blocked degradation of branched aa
CNS defects, mental retardation, death

Back 22

Maple Syrup Urine Disease

Front 23

SCID
Excess dATP prevents production of other deoxyribose nucleotides via ribonucleotide reductase
-> lymphopenia

Back 23

Adenosine Deaminase Definiciency

Front 24

X-linked recessive
Lacks Nucleotide Salvage
HGPRT deficiency -> dec IMP/GMP prod -> inc uric acid excr
retardation
self-mutilation
aggression
hyperuricemia, gout, choreoathetosis

Back 24

Lesch-Nyhan Syndrome

Front 25

Glycogen storage disease type I
glucose-6Pase deficiency
(liver becomes like muscle)
severe fasting hypoglycemia
glycogen accum in liver

Back 25

von Gierke's disease

Front 26

Glycogen storage disease type III
deficiency of debranching enzyme
alpha-1,6-glucosidase

Carbohydrate

Back 26

Cori's Disease

Front 27

Muscle glycogen phosphorylase deficiency
glycogen in muscle -> painful cramps,
myoglobinuria w/ strenuous exercise

Metabolism

Back 27

Glycogen storage disease type V
McArdle's disease

Front 28

acetoacetate and betahydroxybutyrate
made in liver from HMG-CoA
excr in urine (test for acetoacetate)
elevated in starvation/DM ketoacidosis
fruity breath
converted to 2 AcetylCoA in brain

Back 28

Ketone bodies

Front 29

dietary TGs to peripheral tissues, dietary chol to liver
travel in lymphatics to thoracic duct to blood
excess -> xanthomas
Apo B48 mediates excretion
Apo CII for lipoprotein lipase
Apo E mediates liver uptake

Back 29

Chylomicrons

Front 30

hepatic TGs to periphery
excess causes pancreatitis
apo B100 mediates secr
apo CII for lipoportein lipase
apo E mediates liver uptake

Back 30

VLDL

Front 31

produced via VLDL modification
hepatic cholesterol to periphery
uptake via R-med endocytosis (Apo B100)
excess causes ATH, xanthomas
Bad for you

Back 31

LDL

Front 32

periphery cholesterol to liver
repository for Apo C/E
Apo A-1 for LCAT & chol-esters
Good for you

Back 32

HDL

Front 33

Increased Cholesterol/LDL
Auto Dom defect in LDL R
xanthomas
MI before 30y in homozygous pt

Back 33

Familial Hypercholesterolemia

Front 34

Rate limiting step: glycine + succinyl CoA -> ALA via ALA synthase
occurs w/in mitochondria
inhibition -> porphyrias
Pb inhib other enzymes -> microcytic/hypochromic anemia and porphyria

Back 34

Heme Synthesis

Front 35

deficiency: night blindness, dry skin

Back 35

Vitamin A

Front 36

Thiamine, cofactor in pyruvate carboxylase
deficiency: Beriberi and Wernicke's encephalopathy

Back 36

Vitamin B1

Front 37

Riboflavin, FAD/FADH2
deficiency: corneal vascularization, cheilosis

Back 37

Vitmain B2

Front 38

Niacin, NAD/NADH (from Trp)
deficiency: Pellagra
caused by carcinoid syndrome, INH, Hartnup Dz
Diarrhea, Dermatitis, Dememtia

Back 38

Vitamin B3

Front 39

Pantothenate -> Coenzyme A
FA synth, Kreb's Cycle
deficiency: Dermatitis, Enteritis, Alopecia, adrenal insufficiency

Back 39

Vitmain B5

Front 40

Pyridoxine
Converted to Pyridoxal Phosphate
cofactor in transamination (ALT/AST)

Back 40

Vitamin B6

Front 41

cofactor for carboxylation
1. pyruvate -> oxaloacetate
2. acetyl CoA -> malonyl CoA
3. proprionyl CoA -> methylmalonyl CoA

Back 41

Vitamin B7 (Biotin)

Front 42

Coenzyme for 1-C transfer
methylation rxns for nitrogenous bases
most common vitamin deficiency in US: macrocytic, megaloblastic anemia

Back 42

Folic Acid

Front 43

Cobalamin
Cofactor for homocyteine methylation & methylmalyonyl handling
Stored in liver
deficiency caused by: malabsorption (sprue, enteritis, diphyllobothrium latum), pernicious anemia, ileectomy
Dx: Schilling test

Back 43

Vitamin B12

Front 44

Ascorbic Acid
cofactor for hydroxylation of proline/lysine in collagen
facilitates Fe adsorption by keeping it reduced
Deficiency: scurvy = swollen gums, bruising, poor healing

Back 44

Vitamin C

Front 45

increases Ca/PO4 absorption
deficiency: rickets, osteomalacia, hypoCa tetany
excess: hyperCa, stupor,
caused by sarcoidosis mphages producing active D3

Back 45

Vitamin D

Front 46

Rate limiting enzyme is Phosphofructokinase-1 (PFK-1)

Back 46

Glycolysis

Front 47

Rate limiting enzyme is Fructose 1,6 Bisphosphatase

Back 47

Gluconeogenesis

Front 48

Rate limiting enzyme is isocitrate dehydrogenase

Back 48

TCA cycle

Front 49

Rate limiting enzyme is glycogen synthase

Back 49

Glycogen synthesis

Front 50

Rate limiting enzyme is glcogen phosphorylase

Back 50

Glycogenolysis

Front 51

Rate limiting enzyme is glucose 6-phosphate dehydrogenase

Back 51

HMP shunt

Front 52

Rate limiting enzyme is carbamoyl phosphate synthetase II

Back 52

De novo pyrimidine synthesis

Front 53

Rate limiting enzyme is Glutamine PRPP amidotransferase

Back 53

De novo purine synthesis

Front 54

Rate limiting enzyme is Carbamoyl phosphate synthetase I

Back 54

Urea Cycle

Front 55

Rate limiting enzyme is Acetyl CoA carboxylase (ACC)

Back 55

Fatty Acid synthesis

Front 56

Rate limiting enzyme is carnitine acyltranferase I

Back 56

Fatty acid oxydation

Front 57

Rate limiting enzyme is HMG CoA Synthase

Back 57

Ketogenesis

Front 58

Rate limiting enzyme is HMG CoA reductase

Back 58

Cholesterol Synthesis

Front 59

Rate limiting enzyme is NAD+

Back 59

Ethanol Metabolism

Front 60

Deficiency causes delayed wound healing, hypogonadism, decreased adult hair, and anosmia. May predispose to alcoholic cirrhosis.

Back 60

Zinc

Front 61

Fatty acid oxydation, acetyl CoA production, TCA cycle, and oxidative phosphorylation all occur where?

Back 61

In the mitochondria

Front 62

Glycolysis, fatty acid synthesis, HMP shunt, protein synthesis (RER), and steroid synthesis (SER), all occur where?

Back 62

Cytoplasm

Front 63

What are the three reactions that occur in both the cytoplasm and the mitochondria?

Back 63

Heme synthesis, Urea Cycle, and Gluconeogenesis

Front 64

Enzyme found in the liver and beta cells of the pancreas that has a low affinity (high Km) and high capacity (high Vmax) for glucose: It is induced by insulin.

Back 64

Glucokinase

Front 65

Enzyme found in all tissues that has a high affinity and low capacity for glucose. It is not affected by insulin but it inhibited by glucose-6-phosphate

Back 65

Hexokinase

Front 66

What is the reaction of PFK-2 to insulin?

Back 66

Insulin decreases cAMP, decreases, protein Kinase A, and increases PFK-2

Front 67

Which enzyme in the fructose metabolism pathway is increased by glucagon?

Back 67

FBPase-2
Glucagon increases cAMP, increases protein kinase A, and causes fructose to be broken down.

Front 68

What effect does fructose metabolism have on PFK-1?

Back 68

In the fed state, insulin is high, increasing PFK-2. PFK-2 is the most potent inducer of PFK-1, indicating a well fed state in which glucose can be used for energy.

Front 69

Which other enzyme has similar structure and cofactors as pyruvate dehydrogenase? What reaction does it control?

Back 69

alpha-ketoglutarate dehygrogenase
Converts alpha-ketoglutarate to Succinyl CoA

Front 70

Name the oxidative enzyme in the HMP shunt

Back 70

Glucose-6-Dehydrogenase

Front 71

What is the non-oxidative enzyme in the HMP shunt?

Back 71

Transketolase

Front 72

Which two catalase positive bacteria are ppl with chronic granulomatous disease susceptible to?

Back 72

S. aureus and Aspergillus

Front 73

Gluose appears in the blood and urine, causes infantile cataracts- can present as failure to track objects or develop a social smile:

Back 73

Galactokinase Deficiency- causes a buildup of galactose which is converted to Galactitol in the eye (aldose reductase in lens)

Front 74

Enzyme deficiency causes FTT, jaundice, hepatomegaly, infantile cataracts, mental retardation, caused by accumulation of galactose-1-p and Galactitol

Back 74

Galactose 1-phosphate uridyltransferase deficiency

Front 75

In OTC deficiency, what is the excess carbamoyl phoshate converted to?

Back 75

Orotic acid - get orotic acid in blood and urine

Front 76

Causes tremor, slurring of speech, somnolence, vomiting, cerebral edema, and blurring of vision. Is treated by limiting protein in the diet and giving benzoate or phenylbutyrate.

Back 76

Hyperammonemia- can be casued by liver disease or enzyme deficiencies in the Urea cycle (CPS I, arginosuccinase)

Front 77

Causes backup of substrate (pyruvate and alanine) resulting in lactic acidosis. Causes neurologic defects and is treated with ketogenic nutrients like high fat content or increased lysine and leucine.

Back 77

Pyruvate dehydrogenase deficiency

Front 78

Which vitamin functions as a cofactor in gluconeogenesis?

Back 78

Biotin
Activated biotin is a necessary cofactor to convert pyruvate to oxaloacetate.

Front 79

Acyl-CoA undergoes _________ in the mitochondria to yield ketone bodies, acetyl-CoA, and NADH/FADH2.

Back 79

β-oxidation

Front 80

Which of the following inhibits the carnitine shuttle system used to transport acyl-CoA into mitochondria?

Back 80

Malonyl-CoA

Front 81

Uroporphyrinogen III is elevated in __________.

Back 81

Porphyria cutanea tarda, but this affects the skin (blistering)

Front 82

In acute intermittent porphyria, ___________ accumulates and episodically becomes symptomatic.

Back 82

porphobilinogen

Front 83

______________accumulates during lead poisoning, which can mimic acute intermittent porphyria, but it would be unusual for patients with lead poisoning to have recurrent, similar episodes.

Back 83

Coproporphyrin III

Front 84

In alkaptonuria, homogentisate, accumulates because of deficient ___________.

Back 84

HDG (homogentisic acid dioxygenase).