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Biochem
Biochem for USMLE
211
Medical
Professional
03/24/2011

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Term
Orotic aciduria
Definition
In ability to convert orotic acid to UMP (de novo pyrimidine synthesis pathway) due to defect in either orotic acid phophribosytransferase or orotidine 5'-phophate decarboxylase. Autosomal recessive.
incr orotic acid in urine, megalobastic anemia (does not improve with
B12 or folic acid), failure to thrive. No hyperammonemia (vs. OTC def - incr orotic acid with hyperammonemia).
Treatment: oral uridine admin.
Term
Hydroxyurea
Definition
inhibits ribonucleotide reductase
Term
6-mercaptopurine (6MP)
Definition
blocks de novo purine synthesis by blocking amidotransferase
Term
5-fluorouracil (5-FU)
Definition
inhibits thymidylate synthase (decr dTMP)
Term
Methotrexate (MTX)
Definition
inhibits dihydrofolate reductase (decr dTMP)
Term
trimethoprim
Definition
inhibits bacterial dihydrofolate reductase (decr dTMP)
Term
allopurinol
Definition
inhibits xanthine oxidase, interfering w/ conversion of hypoxanthine and xanthine to uric acid
Term
adenosine deaminase def
Definition
Excess ATP and dATP imbalances nucleotide pool via feedback inhibition of rbonucleotide reductase.
prevents DNA synthesis and thus decr lumphocyte count. One of the major causes of SCID
Term
Lesch-Nyhan syndrome
Definition
defective purine salvage owing to absence of HGPRT, which converts hypoxanthine to IMP and guanine to GMP. Results in excess uric acid production. decr feedback inhibition on amidotransferase.
Findings: retardation, self-mutilation, aggression, hyperuricemia, gout, choreoathetosis
Term
charge of lysine and arginine
Definition
positive so they can bind with negatively charged DNA as a part of histone
Term
heterochromatin
Definition
condensed, transcriptionally inactive, sterically inaccessible.
Term
Euchromatin
Definition
Less condensed, transcriptionally active, sterically accessible
Term
Purines
Definition
A, G, 2 rings
Term
Pyrimidines
Definition
C, U, T, 1 ring
Term
G-C bond
Definition
3 H-bonds
Term
A-T boud
Definition
2 H-bonds
Term
transItion
Definition
substituting purine to purine and pyrimidine for pyrimidine
Term
transVersion
Definition
conVersion between types.
Substituting purine for pyrimidine or vice versa
Term
fluroquinolones
Definition
inhibit DNA gyrase (specific prokaryotic topoisomerase)
Term
hereditary nonpolyposis colorectal cancer (HNPCC)
Definition
mismatch repair
Term
mRNA stop codons
Definition
UGA - you go away
UAA - you are away
UAG - u are gone
Term
alpha-amanitin
Definition
found in death cap mushrooms, inhibits RNA polymerase II, causes liver failure if ingested
Term
splicing of pre-mRNA
Definition
1. primary transcript combines with snRNPs and other proteins to form spliceosome.
2. lariat shaped (looped) intermediate is generated
3. lariat is released to remove intro precisely and join 2 exons.
Pt with lupus makes antibodies to spliceosomal snRNPs
Term
aminoacyl-tRNA synthetase
Definition
1 per AA, a matchmaker that uses ATP, it scrutinizes AA before and after it binds to tRNA
Term
tetracyclines
Definition
binds to 30S usbunit, preventing attachment of aminoacyl-tRNA
Term
what activates elongation factor?
Definition
GTP
Term
aminoglycosides
Definition
inhibit formation of the initiation complex and cause misreading of mRNA
Term
choloramphenicol
Definition
inhibits 50S peptidyltransferase
Term
Macrolides
Definition
bind 50S, blocking translocation
Term
Clindamycin
Definition
Binds 50S, blocking translocation
Term
What kind of proteins do free ribosomes synthesize?
Definition
cytosolic and organellar proteins
Term
what kind of cells are rich in SER?
Definition
liver hepatocytes and steroid hormones
Term
what kind of cells are rich in RER
Definition
mucus-secreting goblet cells of the small intestine and antibody-secreting plasma cells
Term
COPI
Definition
a vescicular trafficiking protein
retrograde, Golgi to ER
Term
COPII
Definition
a vesicular trafficking protein
anterograde
RER to cis-Golgi
Term
clathrin
Definition
a vesicular trafficiking protein,
trans-golgi to lysosome
plasma membrane to endosomes (receptor mediated endocytosis)
Term
I-cell disease
Definition
AKA inclusion cell disease
inherited lysosomal storage disorder; failure of addition of mannose-6-phosphate to lysosome proteins (enzymes are screted outside the cell instead of being targeted to the lysosome). Results in coarse facial feature features, clouded corneas, restricted joint movement, and high plasma levels of lysosomal enzymes. Often fatal in childhood
Term
Drugs that act on microtubules
Definition
Mebendazole/thiabendazole (antihelminthic)
Griseofulvin (antifungal)
Vincristine/vinblastine (anti-cancer)
Paclitaxel (anti-breast cancer)
Colchicine (anti-gout)
Term
Chediak-Higashi syndrome
Definition
microtubule polymerization defect, result in decr phagocytosis, recurrent pyogenic infections, partial albinism, and peripheral neuropathy
Term
Kartagener's syndrome
Definition
AKA primary ciliary dyskinesia
immotile cilia due to dynein arm defect. Results in male and female infertility (sperm immotile), bronchiectasis, and recurrent sinusitis (bacteriaand particles not pushed out); associated with situs inversus.
Term
What do microtubules make?
Definition
Cilia, flagella, mitotic spindle, neurons, centrioles
Term
what is made of intermediate filaments
Definition
Vimentin, desmin, cytokeratin, glial bibrillary acid proteins (GFAP), neurofilaments)
Term
What are the following immunohistochemical stains for?
Vimentin
Desmin
Cytokeratin
GFAP
Neurofilaments
Definition
Vimentin - connective tissue
Desmin - muscle
Cytokeratin - epithlial cells
GFAP - Neuroglia
Neurofilaments - Neurons
Term
Quabain
Definition
inhibits sodium/potassium pump by bind to K+ side
Term
Cardiac glycosides
Definition
they are drugs like digoxin and digitoxin. It directly inhibits Na/K ATPase which leads to indirect inhibition of Na/Ca exchange, incr intracelluar Ca -> incr cardiac contractility
Term
What do the following collagen make?
Type I
Type II
Type III
Type IV
Definition
type I - Bone, Skin, Tendon, Dentin, Fascia, cornea, late wound repair
Type II - Cartilage (including hyaline), vitreous body, nucleus pulposus.
Type III - (Reticulin) Skin, blood vessels, uterus, fetal tissue, granulation tissue.
Type IV - Basement membrane or basal lamina
Term
Ehlers-Danlos Syndrome
Definition
Faulty collagen synthesis effecting mostly type III
1. hperextensible skin
2. Tendency to bleed (easy bruising)
3. hypermobile joints
Associated with joint dislocation, berry aneurysms, organ rupture.
Term
Osteogenesis imperfecta
Definition
brittle bone disease caused by gene defects, autosomal dominant
1. multiple fractures
2. Blue Sclerae
3. hearing loss
Dental imperfections due lack of dentin
Term
Alprt's syndrome
Definition
abnormal type IV collagen, X-linked recessive.
Can't see
Can't pee
Can't hear
type IV collagen is an important component of the basement membrane of the kidney, ears, and eyes
Term
Marfan's syndrome
Definition
Autosomal dominant
defect in fibrillin. Elastins are made by tropoelastin with fibrillin scaffolding
Findings: tall with long extremities, pectus exavatum, hyperextensive joints, and long tapering fingers and toes, cystic medial necrosis of aorta -> aortic imcompetence and dissecting aortic aneurysms; floppy mitral value. Subluxation of lenses. asso with berry aneurysm.
Term
Emphysema
Definition
can be caused by alpha antitrypsin def, resulting in excess elastase activity
Term
Prader-Willi syndrome
Definition
Deletion of normally active Paternal allele.
Mental retardation, hyperphagia, obesity, hypogonadism, hypotonia.
Term
AngelMan's syndrome
Definition
Deletion of normally active Maternal allele. Mental retardation, seizusres, ataxia, inappropriate laughter ("happy puppet").
Term
Hypophosphatemic rickets
Definition
X-linked dominant.
formerly known as vitamin D-resistant rickets. Inherited disorder resulting in incr phophate wasting at PCT. Results in rickets like presentation.
Term
Mitochondrial myopahties, Leber's hereditary optic neuropathy
Definition
Mitochondrial inheritance
degeneration of retinal ganglion cells and axons. Leads to acute loss of central vision.
Term
Achondroplasia
Definition
Autosomal dominant
Cell-signallying defect of fibroblast growth factor (FGF) receptor 3. Results in dwarfism; short limbs, but head and trunk are normal size. Asso. with advanced paternal age.
Term
Autosomal-dominant polycystic kidney disease (ADPKD)
Definition
AKA adult polycyctic kidney disease. Always bilateral, massive enlargement of kidneys due to multiple large cycts. Pt presents with flank pain, hematuria, hypertension, progressive renal failure. mutations in APKD1. Asso. with polycyctic liver disease, berry aneurysms, mitral valve prolapse. infantile form is recessive.
Term
Familial adenomatous polyposis (FAP)
Definition
Autosomal dominant
colon becoemes covered with adnomatous polyps after puberty. Progresses to colon cancer unless resected. APC gene.
Term
Familial hypercholesterolemia (hyperlipidmia type IIa)
Definition
autosomal dominant
Elevated LDL due to defective or absent LCL receptor.
Heterozygotes - 300mg/dL
Momozygotes - 700+mg/dL
severe atherosclerotic disease early in life, and tendon xanthomas (classically in the Achilles tendon); MI may develop before age 20. Asso. with hypertrophic cardiomyopathy
Term
Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome)
Definition
Autosomal dominant
Inherited disorder of blood vessels.
Findings: telangiectasia, recurrent epistaxis, skin discolorations, arterovenous malformations (AVMs)
Term
Hereditary sphereocytosis
Definition
autosomal dominant
spheroid erthrocytes due to spectrin or ankyrin defect; hemolytic anemia; incr MCHC. Cure with splenectomy. Test with osmotic fragility test
Term
Huntinton's disease
Definition
autosomal dominant
Depression, progressive dementia, choreiform movements, caudate atrophy, and decr elvels of GABA and ACh in the brain. Symptoms manifest in affected individuals between the ages of 20 and 50. CAG repeat on chromosome 4
Term
Neurofibromatosis type 1
(von Recklinghausen's disease)
Definition
autosomal dominant
cafe au lait spots, nueral tumors, lisch nodules (pigmented iris hamartomas). also marked by skeletal disorders (eg scoliosis), optic pathway gliomas, pheochromocytoma, and incr tumor susceptibility.
Term
Neurofibromatosis type 2
Definition
autosomal dominant
Bilateral acoustic neuroma, juvenile cataracts. NF2 gene on chromosome 22
Term
Tuberous sclerosis
Definition
autosomal dominant
findings: facial lesions (adenoma sebaceum), hypopigmented "ash left spots" on skin, cortical and retinal hamartomas, seizures, mental retardation, renal cysts and renal angiomyolipomas, cardiac rhabdomyomas, incr incidence of astrocytomas. Incomplete penetrance, variable presentation.
Term
Von Hippel-Lindau disease
Definition
autosomal dominant.
hemagioblastomas of retinal/cerebellum/medulla; about half of affected indivduals develop multiple bilateral renal cell carcinoma and other tumors. Associated with deletion of VHL gene (tumor suppressor) on chromosome 3. Results in constitutive expression of HIF (transcription factor) and activation of angiogenic growth factors.
Term
Duchenne's Muscular dystrophies
Definition
X-linked frame shift mutation -> deletion of dystrophin gene ->accelerated muscle breakdown. Weakness begins in plevic girdle muscles and progresses superiorly.
Pseudohypertrophy of calf muscles due to fibrofatty replacement of msucle; cardiac myopathy. Use of Gower's maneuver, requiring assist of supper extremities to stand up, is characteristic. Onset before 5 years of age. Dystrophin gene is the longest known human gene -> incr rate of mutation. Dystrophin helps anchor muscle fibers, primarily in skeletal and cardiac muscle.
Term
Becker's muscular dystrophies
Definition
X-linked mutated dystrophin gene. Less severe than Duchenne's. Onset in adolescence or early adulthood
Term
Fragile X syndrome
Definition
X-linked defect affecting the methylation and expression of the FMR1 gene. Asso. with chromosomal breakage. The 2nd most common cause of genetic mental retardation after Down syndrome).
Findings:macro-orchidism(enlarged testes), long face with a large jaw, large everted ears, autism, mitral valve prolapse.
Trinucleotide repeat disorder (CGG)
Fragile X = extra-large testes, jaw, ears.
Term
Trinucleotide repeat expansion diseases
Definition
Huntington's disease(CAG)
MyoTonic dystrophy(CTG)
FraGile X syndrome(CGG)
Friedreich's ataxia(GAA)
Term
Down syndrome's clinical features
Definition
mental retardation, flat facies, prominent epicanthal folds, simian crease, gap b/t, duodenal atresia, congenital heart disease (most commonly spetum primum-type ASD). Associated with incr risk of ALL and Alzheimer's disease
Term
Down syndrome's tests
Definition
decr alpha fetoprotein, incr beta hCG, decr estril, incr inhibin A, unltrasound shows incr nuchal translucency
Term
Edwards' syndrome
Definition
Trisomy 18
Finds; severe mental retardation, rocker bottom feet, micrognathia(small jaw), low set ears, clenched hands, prominent occiput, congenital heart disease. Death usually occurs within 1 year of birth.
Term
Patau's syndrome
Definition
trisomy 13
severe mental retardation, rocker-bottom feet, microphthalmia, microcephaly, cleft lip/palate, holprosencephaly, polydactyly, congenital heart disease. Death usually occurs within 1 year of birth
Term
Cri-du-chat syndrome
Definition
congenital microdeletion of short arm of chromosome 5
findings: microcephaly, moderate to severe mental retardation, high-pitched crying/mewing, epicanthal folds, cardiac abnormalities
Term
Cri-du-chat syndrome
Definition
congenital microdeletion of short arm of chromosome 5
findings: microcephaly, moderate to severe mental retardation, high-pitched crying/mewing, epicanthal folds, cardiac abnormalities
Term
Williams syndrome
Definition
congenital microdeletion of long arm of chromosome 7(deleted region includes elastin gene).
Findings: distinctive "elfin" facies mental retardation, hypercalcemia (incr sensitivity to vit D), well-developed verbal skills, extreme friendliness with strangers, cardiovascular problems.
Term
DiGeorge syndrome
Definition
22q11
thymic, parathyroid, and cardiac defects
Term
Velocardiofacial syndrome
Definition
22q11
palate, facial, and cardiac defects
Term
Bitot's spots in eye
Definition
AKA xerophthalmia, dry eye, caused by vitamin A def
Term
what vitamin def causes squamous metaplasia (keratinized epithelia)
Definition
Vitamin A def
Term
What is isotretinoin (accutane) similar to?
Definition
Vitamin A, so pregnant women need avoid it because it is a teratogen
Term
What is the enzyme that only needs thiamine to work
Definition
transketolase, which is involved in HMP shunt
Term
what are some of the conditions caused by thiamine deficiency
Definition
Impaired glucose breakdown -> ATP depletion.
Wernicke-Korsakoff
Dry beriberi
Wet beriberi
Term
what can cause thiamine def? name two
Definition
malnutrition and alcoholism
Term
Wernicke-Korsakoff
Definition
confusion, opthalmoplegia, ataxia + memory loss, confabulation, personality change
Term
Dry beriberi
Definition
polyneuritis, symmetrical muscle wasting
Term
wet beriberi
Definition
high-output cardiac failure (dilated cardiomyopathy), edema
Term
What is Vitamin B2?
Definition
Riboflavin, cofactor in oxidation and reduction. FAD and FMN are derived from riboFlavin. Def causes Cheilosis and corneal vascularization. Megenta colored tongue
Term
What causes Vit B3 def
Definition
1. Hartnup disease (decr tryptophan absorption)
2. malignant carcinoid syndrome (incr tryptophan meta)
3. INH (decr vit B6)
Term
what kind of side effects would excess Vit B3 cause?
Definition
excess niacin can cause facial flushing
Term
Can niacin be used for lower LDL?
Definition
yes
Term
What is Pellagra
Definition
3 Ds
Diarrhea
Dermatitis ->hyperpigmentation in sun exposed area, casa's necklace
Dementia
Term
Vitamin B5
Definition
Essential component of CoA and fatty acid synthase
Def causes dermatitis, enteritis, alopecia, adrenal insufficiency.
Term
what can cause B6 def?
Definition
Alcohol and isoniazid
Term
How does B6 def cause sideroblastic anemias?
Definition
Pyridoxine is needed for heme synthesis. Therefore iron builds up in mitochrondria -> sideroblastic anemia
Term
How does B12 def cause neuropathy?
Definition
build up of methylmalonyl-CoA
Term
How is SAM generated?
Definition
ATP + methionine -> SAM
SAM transfers methyl unit and becomes homocysteine. Regeneration of methionine needs Vit B12 and folate
Term
What are the three things carboxylation enzymes need to function
Definition
ATP
Biotin
CO2
Term
What is the most common cause of biotin def
Definition
excessive ingestion of raw eggs
Term
What is vitamin E also known as?
Definition
alpha-tocophenol
Term
what is selenium used for
Definition
form glutathion antioxident
Term
What is the clinical symptoms of Vit K def
Definition
incr PT and PTT, but normal bleeding time
Term
what are zinc fingers?
Definition
transcription factor motif
Term
What does Fomepizole do?
Definition
inhibits alcohol dehydrogenase
Term
What is disulfiram?
Definition
AKA antabuse, inhibits acetaldehyde dehydrogenase
Term
What is the mech of enthanol hypoglycemia
Definition
Ethanol metabolism converts NAD+ to NADH in liver, causing diversion of pyruvate to lactate and OAA to malate, thereby inhibiting gluconeogenesis and stimulating fatty acid synthesis
Term
What is Kwashiorkor?
Definition
protein malnutrition resulting in skin lesion, edema, liver malfunction.
eg: a small child with swollen belly
protein -def MEAL
Malnutrition
Edema
Anemia
Liver(fatty)
Term
What is Marasmus
Definition
energy malnutrition resulting in tissue and muscle wasting
Term
what is the rate determine enzyme of Glycolysis
Definition
Phosphofructokinase-1 (PFK-1)
Term
what is the rate determine enzyme of Gluconeogensis
Definition
Fructose-1,6-biophophatase
Term
what is the rate determine enzyme of TCA cycle
Definition
isocitrate dehydrogenase
Term
what is the rate determine enzyme of glycogen synthesis?
Definition
glycogen synthase
Term
what is the rate determine enzyme of glycogenolysis?
Definition
glycogen phosphorylase
Term
what is the rate determine enzyme of HMP shunt?
Definition
Glucose-6-phosphate dehydrogenase
Term
what is the rate determine enzyme of De novo pyrimidine synthesis?
Definition
Carbamoyl phosphate synthetase II
Term
what is the rate determine enzyme of de novo purine synthesis?
Definition
Glutamine-PRPP amidotranferase
Term
what is the rate determine enzyme of urea cycle?
Definition
Carbamoyl phosphate synthetase I
Term
what is the rate determine enzyme of fatty acid synthesis?
Definition
Acetyl-CoA carboxylase (ACC)
Term
what is the rate determine enzyme of fatty acid oxidation?
Definition
Carnitine acyltransferase I
Term
what is the rate determine enzyme of ketogenesis?
Definition
HMG-CoA synthase
Term
what is the rate determine enzyme of cholesterol synthesis?
Definition
HMG-CoA reductase
Term
what is the rate determine enzyme of heme synthesis?
Definition
amino-levulinic synthase
Term
Where can hexokinase be found and what is its enzyme kinetics?
Definition
ubiquitous. high affinity (low Km) and low capacity (low Vmax), uninduced by insulin
Term
where can gluokinase by found and what is its enzyme kinetics?
Definition
Liver and beta cells of pancreas. Low affinity (high Km) and high capacity(high Vmax), induced by insulin.
Term
Pyruvate kinase def
Definition
most common glycolytic enzyme deficiency
1. hemolytic anemia
2. incr 2,3BPG
3. no Heinz bodies
Term
What does arsenic do?
Definition
inhibits lipoic acid, which is needed for pyruvate dehydrogenase complex. Causes vomiting, rice water stool, garlic breath.
Term
What are the 5 co-factors for Pyruvate dehydrogenase complex?
Definition
Tender loving Care For Nancy
Thiamine (pyrophosphate)
Lipoic acid
CoA (B5, pahtothenate)
FAD (B2, riboflavin)
NAD (B3, niacin)
Term
How to treat pyruvate dehydrogenase deficiency?
Definition
incr intake of ketogenic nutrients
eg: high fat content or high lysine and leucine
Term
what are the two purely ketogenic amino acids?
Definition
Lysine and Leucine
Term
What are the 4 metabolic products of Pyruvate?
Definition
1. Alanine (ALT)
2. oxaloacetae (pyruvate carboxylase)
3. Acetyl-CoA (pyruvate dehydrogenase)
4. Lactate (LDH)
Term
What is the Cori cycle?
Definition
allows lactate generated during anaerobic metabolism to undergo hepatic gluconeogensis and become a source of glucose for muscle/RBC
Term
What are the 3 Tender Loving Care For Nancy enzymes?
Definition
1. PDH
2. alpha ketoglutarate dehydrogenase (TCA)
3. Branched Chain ketoacid dehydrogenase (Maple Syrup urine disease)
Term
Cyanide
Definition
fixes Fe to 3+ state, stops electron transport chain. Treat with Nitrite
Term
What do Rotenone, CN-, antimycin A, and CO do?
Definition
they are electron transport inhibitors
Term
What does oligomycin do?
Definition
its an ATPase inhibitor
Term
What do 2,4 DNP, aspirin, and thermogenin have in common?
Definition
they are all uncoupling agents
Term
How do you get 2,4-DNP poisoning?
Definition
from woo preservation agents
Term
What causes chronic granulomatous disease?
Definition
NADPH oxidase def
Term
What is G6PD def?
Definition
decr NADPH in RBC leads to hemolytic anemia.
X-linked recessive, most common human enzyme deficiency, increased malarial resistance.
Heinz bodies - oxidized hemoglobin percipitation
Bite cells: removal of Heinz bodies by marophages
Term
What is the mech of Fructose intolerance?
Definition
hereditary def of aldolase B, autosomal recessive. fructose-1-phosphate accumulates, causing a decr in available phosphate, results in inhibition of glycogenolysis and gluconeogensis
Term
What are the symptoms and treatment of fructose intolerance?
Definition
symptoms: hypoglycemia, jaundice, cirrhosis, vomiting.
treatment: decr intake of both fructose and sucrose
Term
what is the mech of essential fructosuria?
Definition
defect in fructokinase. Autosomal recessive. Benighn, asymptomatic, fructose does not enter cells
Term
what are the symptoms of essential fructosuria?
Definition
fructose appears in blood and urine
Term
Classic galactosemia
Definition
absence of galactose-1-phosphate uridyltransferase. Autosomal recessive.
symptoms:failure to thrive, jaundice, hepatomegaly, infantile cataracts, mental retardation.
Treatment: exclude galactose and lactose from diet
Term
galactokinase def
Definition
galactitol accumulation. Mild condition. Autosomal recessive.
symptoms: galactose in blood and urine, infantile cataracts. Failure to track objects or to develop a social smile
Term
what causes sorbitol accumulation?
Definition
the lack of sorbitol dehydrogenase in tissue such as schwann cells, lens, retina, and kidney
Term
What is aldose reductase?
Definition
converts glu to sorbitol
Term
what AA are high level in histones?
Definition
Arg and Lys
Term
What two AA transport ammonium?
Definition
alanine and glutamine
Term
what is the mech of ammonia intoxication?
Definition
excess NH4+ depletes alpha-ketoglutarate, leading to inhibition of TCA cycle
Term
what are the clinical signs of ammonia intoxication?
Definition
tremor, slurring of speech, somnolence, vomiting, cerebral edema, blurring of vision
Term
Ornithine transcarbamoylase (OTC) deficiency
Definition
Most common urea cycle disorder. X-linked recessive. excess carbamoyl phophate is converted to orotic acid.
Findings: orotic acid in blood and urine, decr BUN, symptoms of hyperammonemia
Term
4 products from G6P
Definition
1. glucose
2. 6-phosphogluconolactone (HMP shunt)
3. Fructose-6-phosphate (part of glycolysis)
4. glucose-1-phosphate (on to glycogen synthesis)
Term
Derivatives of Phenylalanine
Definition
Tyrosine->Thyroxine
Dopa->Melanin
Dopamine->NE->Epi
Term
Trytophan derivatives
Definition
B6->Niacin->NAD+/NADP+
BH4->serotonin->Malatonin
Term
Histidine derivatives
Definition
B6->Histamine
Term
Glycine derivatives
Definition
B6->Porphrine->Heme
Term
Arginine derivatives
Definition
Creatine
Urea
Nitric Oxide
Term
Glutamate derivatives
Definition
B6->GABA(glutamate decarboxylase-requires B6)
Glutathione
Term
Phenylketonuria
Definition
Due to decr phenylalanine hydroxylase or decr tetrahydrobiopterin cofactor. Tyrosine becomes essential. incr phenylalanine leads to excess phenylketones in urine.
Findings: mental retardation, growth retardation, seizures, fair skin, eczema, musty body order.
Treatment: decr phenylalanine and incr tyrosine
Term
Maternal PKU
Definition
lack of proper dietary therapy during pregnancy. Findings in infant: microecephaly, mental retardation, growth retardation, congenital heart defects
Term
Alkaptonuria (ochronosis)
Definition
congenital def of homogentisic acid oxidase in the degradative pathway of tyrosine. Autosomal recessive. Benign disease.
Findings: dark connective tissue, pigmented sclera, urine turns black on standing. May have debilitating arthralgias
Term
what are the two mech of albinism?
Definition
1. Def of tyrosinase (inability to synthesize melanin from tyrosine)-autosomal recessive.
2. Defective tyrosine transporters (decr amounts of tyrosine and thus melanin)
Term
What are the clinical symptoms of homocystinuria
Definition
excess homocysteine. Custeine becomes essential.
Findings: incr homocysteine in urine, mental retardation, osteoporosis, tall stature, kyphosis, lens subluxation (downward and inward), and atherosclerosis (stroke and MI)
Term
what are the three forms of homocystinuria?
Definition
1. cystathionine synthase def
Treatment: decr met and incr Cys, B12, and folate
2. decr affinity of cystathionine synthase for pyridoxal phosphate. treatment: incr vit B6 in diet.
3. Homocysteine methyltranferase def
Term
Cystinuria
Definition
hereditary defect of renal tubular amino acid transporter for cysteine, ornithine, lysine, and arginine in the PCT of the kidneys.
Excess cystine in urine can lead to the precipitation of cystine kidney stones (cystine staghorn calculi)
Treatment: acetazolamide to alkalinize the urine.
Term
Maple syrup urine disease
Definition
Blocked degradation of branched amino acids (Ile, Leu, Val) due to decr alpha-ketoacid dehydrogenase (aka branched chain ketoacid dehydrogenase). causes incr alpha keotacids in the blood, especially leu.
Causes severe CNS defects, mental retardation, and death.
I Love Vermont maple syrup
Term
Hartnup disease
Definition
Autosomal-recessive disorder characterized by defective neutral amino acid transporter on renal and intestinal epithelial cells.
Causes tryptophan excretion in urine and absorption from the gut. Leads to Pellagra.
Term
alpha (1,6) bonds
Definition
Branches
Term
alpha (1,4) bonds
Definition
linkages
Term
Von Gierke's disease
Definition
Type I
Severe fasting hypoglycemia, incr glycogen in liver, incr blood lactate, hepatomegaly
Glucose-6-phosphatase def
Term
Pompe's disease
Definition
type II
Cardiomegaly and systemic findings leading to early death
Lysosomal alpha-1,4-glucosidase def
Pompe's trashes the pump (heart, liver, and muscle).
Term
Cori's disease
Definition
Type III
Milder form of type I glycogen storage disease with normal blood lactate levels. Def debranching enzyme, gluconeogenesis is intact.
Term
McArdle's disease
Definition
Type V
incr glycogen in muscle, but cannot break it down, leading to painful muscle cramps, myoglobinuria with strenuous excercise.
Skeletal muscle glycogen phophorylase.
McArdle's = muscle
Term
Anderson's disease
amylopectinosis
Definition
Type IV glycogen storage disease
infantile hypotonia, cirrhosis, death by 2 years.
branching enzyme def
glycogen has very few branches
Term
Hers's disease
Definition
Type VI glycogen storage disease
Mild Fasting hypoglycemia, hepatomegaly, cirrhosis.
Heptatic glycogen phophorylase (liver only)
Term
Fabry's disease
Definition
Peripheral nuropathy of hands/feet, angiokertomas, cardiovascular/renal disease
alpha-galactosidase A def
Ceramide trihexoside accumulation
X-linked recessive
Term
Gaucher's disease
Definition
Most common lysosomal storage disease
Hepatosplenomegaly, aseptic necrosis of femur, bone crises, Gaucher's cells (macrophages that look like crumpled tissue paper)
beta-glucocerebrosidase def
gluocerebroside accumulation
Autosomal recessive
Term
Niemann-Pick disease
Definition
Progressive neurodegeneration, hepatosplenomegaly, cherry-red spot on macula, foam cells
sphingomyelinase def
sphingomyelin accumulation
autosomal recessive
Term
Tay-Sacks disease
Definition
Progressive Neurodegeneration, developmental delay, cherry-red spot on macula, lysosomes with onion skin, no hepatosplenomegaly (vs Niemann-Pick)
Hexosaminidase A def
GM2 ganglioside accumulation
Autosomal recessive
Term
Tay-Sachs, Niemann-Pick, and some forms of Gaucher's disease are elevated in which race?
Definition
Ashkenazi Jews
Term
What's the Citrate shuttle's role in fatty acid metabolism?
Definition
to transport Acetyl-CoA out of Mito for FA synthesis
Term
What is the role of Carnitine Shuttle's role in fatty acid metabolism?
Definition
transport acyl-CoA into Mito for fatty acid degradation
Term
Acyl-CoA dehydrogenase def
Definition
incr dicarboxylic acids
decr glucose and ketones
Term
Carnitine def
Definition
inability to transport LCFAs into the mito, resulting in toxic accumulation. Causes weakness, hypotonia, and hypoketotic hypoglycemia
incr muscle triglyeride
Term
What are the 3 ketone bodies
Definition
Acetone (we can't use it)
Acetoacetate
beta-hydroxybutyrate
Term
What does lecithin-cholesterol acyltransferase (LCAT) do?
Definition
esterify plasma cholesterol so they don't change cell membrane cholesterol composition. Done in blood
Term
What are LCAD, MCAD, and SCAD?
Definition
long, mediium, and short chain Acyl-CoA dehydrogenase.
Term
Pancreatic lipase
Definition
degradation of deitary TG in small intestine
Term
Lipoprotein lipase (LPL)
Definition
degradation of TG circulating in chylomicrons and VLDLs
Term
Hepatic TG lipase
Definition
degradation of TG remaining in IDL
Term
Hormone sensitive lipase
Definition
degradation of TG stored in adipocytes
Term
Cholesterol ester transfer protein (CETP)
Definition
mediates transfer of cholesterol esters to other lipoprotein particles
Term
A-I
Definition
Activates LCAT
Term
B-100
Definition
Binds to LDL receptor, mediates VLDL secretion
Term
C-II
Definition
co-factor for lipoprotein lipase
Term
B-48
Definition
mediates chylomicron secretion
Term
Apolipoprotein E
Definition
mediates extra (remnanant) uptake by liver
Term
apoliporpteins C3
Definition
inhibits lipoprotein lipase
Term
what is ACAT?
Definition
esterifies cholesterol, done inside cells
Term
Chylomicron
Definition
Delivers dietary TGs to peripheral tissue. Delivers cholesterol to liver in the form of chylomicro remnants, which are mostly depleted of their triacylglycerols. Secreted by intestinal epithelial cells
has B-48, A-IV, C-II, and E
Term
VLDL
Definition
Delivers hepatic TGs to peripheral tissue secreted by liver. synthesis inhibited by ETOH. has B-100, C-II, and E
Term
IDL
Definition
formed in the degradation of VLDL. Delivers triglyerides and cholesterol to liver, where they are degraded to LDL.
has B-100 and E
Term
LDL
Definition
Dlivers hepatic cholesterol to peripheral tissues. Formed by lipoprotein lipase modification of VLDL in the peripheral tissue. Taken up by target cells via receptor medicated endocytosis. Has B-100
Term
HDL
Definition
Mediates reverse cholesterol transport from periphery to liver. Acts as repository for apoC and apoE (which are needed for chylomicron and VLDL metabolism). Secreted from both liver and intestine.
Term
type I hyperchylomicronemia
Definition
increased chylomicrons and VLDL after high carb meal, elevated blood TG and cholesterol. Lipoprotein lipase deficiency or altered apolipoprotein C-II. Causes pancreatitis, hepatosplenomegaly, and eruptive/pruritic xanthomas (no increased risk for athersclerosis).
Term
type IIa familial hypercholesterolema
Definition
increased LDL and elevated blood chilesterol. autosomal dominant; absent or decr'd LDL receptor. Causes accelerated atherosclerosis, tendon (Achilles) xanthomas, and corneal arcus.
Term
Type IV hypertriglyceridemia
Definition
incr'd VLDL and elevated blood TG, hepatic overproduction of VLDL. Causes pancreatitis
Term
Abeta-lipoproteinemia
Definition
Hereditary inability to synthesize lipoproteins due to def in apoB-100 and apoB-48. Autosomal recessive. Symptoms appear in the first few months of life. Intestinal bipsy shows accumulation within enterocytes due to inability to export absorbed lipid as chylomicrons.
Findings: failure to thrive, steatorrhea, acanthocytosis, ataxia, night blindness.
Term
what's genetic term describes the tendency for certain alleles at linked loci to occur together more often than expected by chance. Measured in a population, not in a family, and often varies in different populations
Definition
Linkage disequilibrium.
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