Usmle Step 1 Flashcards - Biochem

Front 1

Exceptions to universal genetic code

Back 1

Mitochondria, archaebacteria, Mycoplasma, and some yeast

Front 2

Type of DNA repair for T-T dimers?

Back 2

Nucleotide excision repair (mutated in xeroderma pigmentosum)

Front 3

Type of DNA repair for oxidized, alkylated, or deaminated bases?

Back 3

Base excision repair

Front 4

Condition due to defect in DNA mismatch repair

Back 4

Hereditary nonpolyposis colorectal cancer (HNPCC) (microsatellite instability)

Front 5

Which prokaryotic DNA polymerase has 5' --> 3' exonuclease activity?

Back 5

DNA Pol 1 (degrades RNA primers)

Front 6

What is alpha amanitin and what does it cause if ingested?

Back 6

It inhibits RNA polymerase II (normally makes mRNA) and causes liver failure if ingested.

Front 7

What is the initial eukaryotic RNA transcript called? (before processing)

Back 7

heterogeneous nuclear RNA (hnRNA)

Front 8

Who makes antibodies to spliceosomal snRNPs?

Back 8

Patients with lupus!

Front 9

Which enzyme is responsible for matching anticodons to the correct amino acids? Where does the energy come from?

Back 9

Aminoacyl-tRNA synthetase (uses ATP)

Binding of the charged tRNA to the codon uses GTP.

Front 10

Which ribosomal subunit does the mRNA first bind to?

Back 10

The small one - 40S in eukaryotes, 30S in prokaryotes (with the help of eIFs)

Front 11

What are 4 examples of permanent cells (remain in G0)?

Back 11

Neurons, Cardiac cells, RBCs, Skeletal muscle cells

Front 12

What are two examples of stable/quiescent cells?

Back 12

Hepatocytes & Lymphocytes

Front 13

What are 4 examples of labile cells?

Back 13

Bone marrow, Gut epithelium, Skin, Hair Follicles

Front 14

List several cell types rich in RER

Back 14

Goblet cells (secrete mucus), plasma cells (secrete Abs), neurons (Nissl bodies, make enzymes/neurotransmitters)

Front 15

List several cell types rich in SER

Back 15

Liver hepatocytes, gonads, and adrenal cortex (SER = steroid hormone synthesis, drug/poison detox)

Front 16

Disease? Coarse facial features, clouded cornea, restricted joint movement, high plasma levels of lysosomal enzymes

Back 16

I-cell disease

Front 17

What does the Golgi apparatus do involving oligosaccharides?

Back 17

MODIFIES N-oligosacc on asn and ADDS O-oligosacc to ser and thr

Front 18

What are COP1 and COP2?

Back 18

Vesicular trafficking proteins: COP I (Golgi to ER), COP II (RER to cis Golgi)

Front 19

What happens between pro-collagen and tropocollagen?

Back 19

It is exocytosed from the cell & the terminals are cleaved.

Front 20

What happens between pre-pro-collagen and pro-collagen?

Back 20

It is hydroxylated (on proline and lysine) (with the help of Vit C) and glycosylated (on lysine) to become a triple helix

Front 21

Describe the cross-linking of collagen.

Back 21

It is covalently cross linked at lysine-hydroxylysine residues by lysyl oxidase (which uses Cu). Defect causes Ehlers-Danlos.

Front 22

What do desmin and vimentin stain for? What are they?

Back 22

Desmin = muscle
Vimentin = connective tissue
They are both intermediate filaments.

Front 23

Disease? Recurrent pyogenic infections, partial albinism, and peripheral neuropathy

Back 23

Chediak-Higashi syndrome (microtubule polymerization defect)

Front 24

Disease? Male & female infertility, bronchiectasis, recurrent sinusitis, situs invertus

Back 24

Kartagener's syndrome (immotile cilia - dynein arm defect)

Front 25

What are microtubules made of?

Back 25

Alpha and beta tubulin dimer helices (each dimer has 2 GTP bound)

Front 26

Disease? Multiple fractures, blue sclerae, hearing loss, dental imperfections, often confused with child abuse

Back 26

Osteogenesis imperfecta (brittle bone disease) (type I collagen)

Front 27

Disease? Hyperextensible joints, easy bleeding, hypermobile joints, berry aneurysms/organ rupture

Back 27

Ehler's Danlos (type III collagen)

Front 28

Disease? Hereditary nephritis and deafness, ocular disturbances

Back 28

Alport's syndrome (type IV collagen)

Front 29

Name 2 diseases of elastin & their pathophys

Back 29

Marfan's syndrome (fibrillin defect) and emphysema (alpha-1-antitrypsin deficiency)

Front 30

Disease? Mental retardation, seizures, ataxia, inappropriate laughter

Back 30

Angelman's syndrome

Front 31

Disease? Mental retardation, hyperphagia, obesity, hypogonadism, hypotonia

Back 31

Prader-Willi syndrome

Front 32

Definition of heteroplasmy

Back 32

Presence of both normal and mutated mtDNA --> results in variable expression of mitochondrial inherited disease

Front 33

What is X inactivation in females called? What can it cause if it's random?

Back 33

Lyonization. Can cause mosaicism if random.

Front 34

Dominant negative effect definition

Back 34

A heterozygote produces a nonfunctional altered protein that also prevents the normal gene product from functioning (ex: mutated tx factor that can still bind DNA)

Front 35

Marfanoid habitus can be caused by Marfan's syndrome, MEN 2B, and homocystinuria. What genetic term is this an example of?

Back 35

Locus heterogeneity (mutations at different loci can produce the same phenotype)

Front 36

Inheritance of hypophosphatemic rickets

Back 36

X-linked DOMINANT (phosphate wasting at proximal tubule)

Front 37

Pathophys of Leber's hereditary optic neuropathy

Back 37

degeneration of retinal ganglion cells and axons --> acute loss of central vision

Front 38

Disease/cause? Microcephaly, mental retardation, high pitched crying, epicanthal folds, cardiac abnormalities

Back 38

Cri-du-chat syndrome (microdeletion of short arm of chromosome 5)

Front 39

Symptoms of Williams syndrome (microdeletion of long arm of chromosome 7)

Back 39

"elfin" facies, mental retardation, hyper-Ca, well developed verbal skills, friendliness, CV problems

Front 40

Trinucleotide repeats: CAG, GAA, CTG, CGG. Diseases?

Back 40

Huntington's (CAG), Friedrich's ataxia (GAA), Myotonic dystrophy (CTG), Fragile X (CGG)

Front 41

Pregnancy quad screen results in Down syndrome

Back 41

Low AFP, low estriol, high beta-HCG, high inhibin A

Front 42

Shared symptoms between Edwards' and Patau's syndromes

Back 42

Severe mental retardation, rocker-bottom feet, congenital heart disease

Front 43

The "P"s of Patau's syndrome

Back 43

"Puberty" chromosome (13), cleft lip/Palate, holoProsencephaly, Polydactyly

Front 44

Disease? Micrognathia, low set ears, clenched hands, prominent occiput, death within 1 year

Back 44

Edwards' Syndrome (trisomy 18)

Front 45

Disease? Telangiectasia, recurrent epistaxis, skin discoloration, AVM

Back 45

Hereditary hemorrhagic telangiectasis (Osler-Weber-Rendu syndrome)

Front 46

Findings with NF1 (von Recklinghausen's disease)?

Back 46

cafe-au-lait spots, neural tumors, Lisch nodules (pigmented iris hamartomas), scoliosis, optic pathway glioma

Front 47

Pathophys of VHL?

Back 47

Deletion of VHL (tumor suppressor) gene (chromosome 3) --> constitutive expression of HIF (txn factor) --> activation of angiogenic growth factors

Front 48

Findings with Fragile X (FMR1 gene)

Back 48

eXtra-large testes, jaw, & ears, autism, mitral valve prolapse

Front 49

How are muscular dystrophies diagnosed?

Back 49

Muscle biopsy and increased CPK

Front 50

Several uses of N-acetylcysteine

Back 50

CF (loosen mucus plugs), prevent kidney disease due to dye, acetaminophen overdose

Front 51

2 enzymes that B12 is a cofactor for

Back 51

Homocysteine methyltransferase (Homocys --> met) and methylmanolyl-CoA mutase (methylmal-CoA --> succinyl CoA)

Front 52

Form of methionine that transfers methyl unit

Back 52

S-adenosyl-methione (SAM) (regeneration is dependent on B12 and folate)

Front 53

Dermatitis, enteritis, alopecia, adrenal insufficiency. Vitamin deficiency?

Back 53

Vitamin B5 (pantothenate). Could also be biotin.

Front 54

Causes of pellagra (B3 deficiency)?

Back 54

Hartnup disease, carcinoid syndrome, INH (dec B6)

Front 55

What types of tissue does B1 deficiency affect first?

Back 55

Highly aerobic tissues (brain and heart) affected first --> polyneuritis, high output heart failure, Wernicke-Korsakoff, etc

Front 56

Cheilosis, corneal vascularization. Vitamin deficiency?

Back 56

B2 (riboflavin)

Front 57

Convulsions, hyperirritability, peripheral neuropathy, sideroblastic anemia. Vitamin deficiency?

Back 57

B6 (pyridoxine)

Front 58

Weak immune response, swollen gums, bruising, hemarthrosis, anemia, poor wound healing. Vitamin deficiency?

Back 58

Vitamin C (scurvy)

Front 59

Increased fragility of erythrocytes, muscle weakness, posterior column/spinocerebellar tract demyelination. Vitamin deficiency?

Back 59

Vitamin E (antioxidant)

Front 60

Biotin is a cofactor for what type of reaction?

Back 60

Carboxylation!

Pyruvate carboxylase, Acetyl-CoA carboxylase, and Propionyl CoA carboxylase

Front 61

How does ethanol cause hypoglycemia? What else is a consequence of this mechanism?

Back 61

Increases NADH/NAD+ ratio in liver --> diverts pyr to lactate and OAA to malate --> inhibits gluconeogenesis. ALSO causes fatty change in liver due to increased fatty acid synthesis.

Front 62

Decreased adult hair, delayed wound healing, hypogonadism, dysgeusia, anosmia. Deficiency?

Back 62

Zinc

Front 63

Inhibitor of alcohol dehydrogenase and use?

Back 63

Fomepizole. Used as antidote for methanol or ethylene glycol poisoning.

Front 64

4 uses of NADPH

Back 64

1. Anabolic reactions
2. Respiratory burst (NADPH oxidase)
3. P-450 reductase
4. Glutathione reductase (GSSG --> GSH)

Front 65

Which 3 pathways take place in both the mitochondria and the cytosol?

Back 65

Heme synthesis, Urea cycle, Gluconeogenesis (HUGs take "two")

Front 66

TPP: Vitamin it comes from and enzymes it's a cofactor for?

Back 66

From Vitamin B1 (thiamine). Cofactor for PDH (glycolysis), alpha-KG Dhase (TCA), TK (HMP shunt), branched-chain aa Dhase

Front 67

4 things pyruvate can be converted to

Back 67

Alanine (via ALT), oxaloacetate (PC), acetyl CoA (PDH), lactate (LDH)

Front 68

Findings with arsenic intake

Back 68

Rice water stool, garlic breath, and vomiting

Front 69

Cofactors for PDH

Back 69

TPP (B1), FAD (B2), lipoic acid, NADH (B3), CoA (B5)

Front 70

Oligomycin inhibits what?

Back 70

ATPase --> proton gradient builds up

Front 71

What 2 types of oxidative phosphorylation poisons DECREASE the proton gradient?

Back 71

Electron transport inhibitors (rotenone, CN-, antimycin A, and CO) and uncoupling agents (2,4-DNP and aspirin)

Front 72

Do odd or even chain FAs produce products that can undergo gluconeogenesis?

Back 72

ODD chain FAs (propionyl CoA → methylmalonyl CoA → succinyl CoA → OAA → gluconeogenesis)

Front 73

Most common human enzyme deficiency & histo findings?

Back 73

G6PD. See Heinz bodies (oxidized Hgb) and Bite cells.

Front 74

Aldolase A vs B?

Back 74

Aldolase A: present in normal glycolysis (F-1,6-BP to DHAP and G3P).

Aldolase B: breaks down F-1-P to DHAP and glyceraldehyde.

Front 75

What sugar can cause infantile cataracts?

Back 75

Galactose (via galactitol). Enzyme deficiencies include galactokinase or galactose-1-phosphate uridyltransferase.

Front 76

Why does sorbitol accumulate in the lens, retina, and kidney, and Schwann cells?

Back 76

They have aldose reductase (glucose → sorbitol) BUT lack sorbitol Dhase, which would otherwise convert sorbitol to fructose.

Front 77

Ketogenic only amino acids?

Back 77

Leu and Lys (used as treatment for PDH deficiency)

Front 78

Glucogenic only amino acids?

Back 78

Val, Arg, His, Met (“Valium Are His Methods”)

Front 79

Glucogenic AND ketogenic amino acids?

Back 79

Ile, Phe, Thr, Trp

Front 80

Which steps of the urea cycle occur in the mitochondria?

Back 80

Carbamoyl phosphate synthetase I (rate limiting step) and ornithine transcarbamoylase

Front 81

What are two hyperammonemia treatments that bind amino acids and lead to their excretion?

Back 81

Phenylbutyrate and benzoate

Front 82

What reaction is SAM used as a methyl donor for?

Back 82

NE to Epi and DNA methylation (imprinting)

Front 83

What 3 compounds arise from arginine?

Back 83

Creatine, Urea, NO

Front 84

What form does glucose need to be in to be utilized for glycogen?

Back 84

UDP-glucose (glucose-1-phosphate is immediate precursor)

Front 85

List 3 causes of albinism.

Back 85

1) Deficiency of tyrosinase (synthesis of melanin from tyrosine), 2) Defective tyrosine transporters, 3) Lack of migration of NCCs

Front 86

3 causes of homocystinuria.

Back 86

1) Cystathionine synthase deficiency, 2) Decreased affinity of cystathionine synthetase for PLP (B6), 3) Homocysteine methyltransferase deficiency

Front 87

Disease? FTT, steatorrhea, acanthocytosis, ataxia, night blindness.

Back 87

Abetalipoproteinemia (deficient apoB-100 and apoB-48)

Front 88

How much energy do you get from 1g of protein or carb compared to 1g of fat?

Back 88

1 g protein/carb = 4kcal, 1 g fat = 9kcal

Front 89

Which has greater muscle wasting: kwashiorkor or marasmus?

Back 89

Marasmus. "M" for "muscle" wasting.

Front 90

Top 2 causes of mental retardation as a result of chromosomal abnormality?

Back 90

1. Down syndrome
2. Fragile X syndrome

Fragile X is top cause of INHERITED mental retardation.

Front 91

Amino acids necessary for purine synthesis?

Back 91

Glutamine
Aspartate
Glycine

Front 92

Compounds that comprise purine ring?

Back 92

Glutamine
N10-Formyl-THF
Glycine
Aspartate
CO2

Front 93

Components of pyrimidine ring?

Back 93

Cabamoyl phosphate and Aspartate

Front 94

Pathway from UMP to dTMP?

Back 94

UMP --> UDP --> dUDP --> dUMP --> dTMP

Front 95

What inhibits ribonucleotide reductase?

Back 95

Hydroxyurea

Front 96

What does 5-FU inhibit?

Back 96

Thymidylate synthase
(dUMP --> dTMP)

Front 97

Effect of 6-mercaptopurine (6-MP)?

Back 97

Blocks de novo purine synthesis (at several steps)

Front 98

CPS II catalyzes what reaction?

Back 98

ATP + CO2 + gln --> carbamoyl phosphate

- 1st step of de novo pyrimidine synthesis

Front 99

GMP, IMP, and AMP breakdown?

Back 99

GMP --> guanosine --> guanine
IMP --> inosine --> hypoxanthine
AMP --> adenosine --> inosine --> hypoxanthine

--> xanthine --> uric acid

Front 100

What kind of DNA repair is used for dsDNA breaks (as a result of ionizing radiation)?

Back 100

Nonhomologous end joining
- brings together 2 ends of DNA fragments

Front 101

First step of nucleotide vs base excision repair?

Back 101

Nucleotide excision: **endonuclease** releases oligonucleotide with damaged bases

Base excision: specific **glycosylases** recognize and remove damaged DNA bases

Front 102

Key intron nucleotides?

Back 102

Exon 1 -- GU ------ A ------ AG -- Exon 2

Front 103

What happens to introns after splicing?

Back 103

They stay in the nucleus

Front 104

Eukaryotic vs prokaryotic RNA polymerase?

Back 104

Prokaryotes: 1 RNA polymerase makes all 3 kinds of RNA

Eukaryotes: RNA Pol I (rRNA), RNA Pol II (mRNA), RNA Pol III (tRNA)

Front 105

Polyadenylation signal? Corresponding sequence at 3' end of DNA strand?

Back 105

AAUAAA

On DNA: AATAAA

Front 106

AUG significance in eukaryotes vs prokaryotes?

Back 106

Eukaryotes: codes for methionine

Prokaryotes: codes for formyl-methionine (f-Met)

Front 107

How much energy does the aa-tRNA bond contain?

Back 107

Enough for the formation of the peptide bone.

- Aminoacyl tRNA synthetase uses ATP to form the bond

Front 108

Different aspects of tRNA structure?

Back 108

Acceptor stem (covalently binds aa)
T loop (binds ribosomes)
Variable loop
Anticodon loop
D loop (has dihydrouracil)

Front 109

What do aminoglycosides inhibit?

Back 109

Formation of the initiation complex --> cause misreading of mRNA

Front 110

What is needed for translation initiation?

Back 110

GTP for translocation, initiation factors (eIFs), and 40S ribosomal subunit with initiator tRNA

Front 111

Site of addition of N-linked vs O-linked oligosaccharides?

Back 111

N-linked oligosacchs: added in RER --> modified in Golgi

O-linked oligosacch: added to serine and threonine residues in Golgi

Front 112

Cyclins and CDKs: which are constitutively active?

Back 112

CDKs: constitutive and inactive

Cyclins: phase specific, activate CDKs

Front 113

Location of Type I collagen?

Back 113

Bone, Skin, Tendon, Dentin, Fascia, Cornea, Late wound repair

Front 114

Location of Type II collagen?

Back 114

Cartilage (including hyaline), Vitreous body, Nucleus pulposus

Front 115

Location of Type III collagen (reticulin)?

Back 115

Skin, Blood vessels, Uterus, Fetal tissue, Granulation tissue

Front 116

Location of Type IV collagen?

Back 116

Basement membrane or Basal lamina

Front 117

What form of collagen is exocytosed from the fibroblast?

Back 117

Pro-collagen
- terminal regions are cleaved outside the fibroblast, converting it to tropocollagen

Front 118

Cytoskeletal elements made from actin and myosin?

Back 118

Microvilli
Muscle contraction
Cytokinesis
Adherens junction

Front 119

Cytoskeletal elements made from microtubules?

Back 119

Cilia
Flagella
Mitotic spindle
Neurons
Centrioles

Front 120

Cytoskeletal elements made from intermediate filaments?

Back 120

Vimentin
Desmin
Cytokeratin
Glial fibrillary acid protein (GFAP)
Neurofilaments

Front 121

Drugs that act on microtubules?

Back 121

1. Mebendazole/thiabendazole
2. Griseofulvin
3. Vincristine/vinblastine
4. Paclitaxel
5. Colchicine

Front 122

What does a southwestern blot identify?

Back 122

DNA binding proteins by their binding to oligonucleotides

Front 123

Elastin composition and locations where it's found?

Back 123

Lungs, large arteries, elastic ligaments, vocal cords, ligamenta flava

Rich in non-glycosylated glycine and proline.

Front 124

What types of diseases have variable expression in the population due to heteroplasmy?

Back 124

Diseases w/ mitochondrial inheritance

Ex: mito myopathies, Leber's hereditary optic neuropathy

Front 125

X-linked mucopolysaccharidosis and sphingolipidosis?

Back 125

Mucopolysaccharidosis: Hunter's

Sphingolipidosis: Fabry's

(All of the rest of each are autosomal recessive)

Front 126

In what muscles does weakness begin in Duchenne's muscular dystrophy?

Back 126

Begins in pelvic girdle muscles and progresses superiorly

Front 127

Gene defect in Fragile X?

Back 127

FMR1 gene
- methylation and expression are affected

Front 128

Microdeletions: Short arm of chromosome 5? Long arm of chromosome 7?

Back 128

Cri-du-chat: short arm of 5

Williams: long arm of 7
- deleted region includes elastin gene

Front 129

What does ultrasound show in Down syndrome?

Back 129

Nuchal translucency

Front 130

Genetic causes of Down syndrome?

Back 130

95% meiotic non-disjunction (associated w/ AMA)
4% robertsonian translocation
1% Down mosaicism (no maternal assoc)

Front 131

Telangiectasia, recurrent epistaxis, skin discolorations, AVMs. Disease?

Back 131

Osler-Weber-Rendu syndrome
(hereditary hemorrhagic telangiectasia)

Front 132

Juvenile cataracts and bilateral acoustic schwannomas. Disease?

Back 132

Neurofibromatosis type 2
- NF2 gene on chromosome 22

Front 133

What can worsen thiamine (B1) deficiency?

Back 133

Glucose infusion
- impaired glucose breakdown/ATP depletion

Front 134

Function of vitamin B5 (pantothenate)?

Back 134

Essential component of CoA (cofactor for acyl transfers) and fatty acid synthase

Front 135

Functions of vitamin B6 (pyridoxine)?

Back 135

Converted to PLP which is used in:
Transamination (ALT/AST)
Decarboxylation reactions
Glycogen phosphorylase
Cystathionine synthesis
Heme synthesis

Front 136

Who is folic acid deficiency commonly seen in?

Back 136

Alcoholics and pregnancy/OCP use.

Also elderly, goat's milk, and malabsorption.

Front 137

Location of alcohol vs aldehyde dehydrogenase?

Back 137

Alcohol dhase: in cytosol

Aldehyde dhase: in mitochondria

Front 138

Rate limiting step of gluconeogenesis?

Back 138

Fructose-1,6-bisphosphatase

Front 139

Rate limiting step of TCA cycle?

Back 139

Isocitrate dehydrogenase

Front 140

Rate limiting step of glycogen synthesis and glycogenolysis?

Back 140

Glycogen synthesis: glycogen synthase

Glycogenolysis: glycogen phosphorylase

Front 141

Rate limiting step of fatty acid synthesis and oxidation?

Back 141

FA synthesis: Acetyl-CoA carboxylase (ACC)

FA oxidation: Carnitine acyltransferase I

Front 142

3 factors that are increased in exercise and activate PDH?

Back 142

Increased NAD+/NADH ratio
Increased ADP
Increased Ca

Front 143

Where is anaerobic glycolysis the major form of glycolysis?

Back 143

RBCs
Leukocytes
Kidney medulla
Lens
Testes
Cornea

Front 144

Names and locations of irreversible enzymes in gluconeogenesis?

Back 144

Glucose-6-phosphatase: ER
Fructose-1,6-bisphosphatase: cytosol
PEP carboxykinase: cytosol
Pyruvate carboxylase: mitochondria

Front 145

Energy source of pyruvate carboxylase and PEP carboxykinase?

Back 145

Pyruvate carboxylase: uses ATP
(also uses biotin as a cofactor)
- activated by acetyl CoA

PEP carboxykinase: uses GTP

Front 146

Transketolases participate in which part of the HMP shunt?

Back 146

Nonoxidative (reversible)

Ribulose-5-P --> TK --> Ribose-5-P, G3P, F6P

Front 147

Products of the oxidative (irreversible) part of the HMP shunt?

Back 147

CO2, 2 NADPH, and Ribulose-5-P

Catalyzed by Glucose-6-P-Dhase

Front 148

Sites in body where HMP shunt takes place?

Back 148

Lactating mammary glands, liver, adrenal cortex, RBCs

Front 149

Two ways that NADH can enter the mitochondria?

Back 149

Malate-aspartate shuttle
Glycerol-3-phosphate shuttle

Front 150

Effects of aldolase B deficiency?

Back 150

Fructose intolerance
- Fructose-1-phosphate accumulates --> decreases available phosphate --> inhibits glycogenolysis and gluconeogenesis
- Hypoglycemia, jaundice, cirrhosis, vomiting

Front 151

How might galactokinase deficiency present?

Back 151

May initially present as failure to track objects or to develop a social smile.

Front 152

Pathway of reduction starting with G6P?

Back 152

G6P reduces NADP+ --> NADPH reduces GS-SG --> GSH reduces H2O2 --> 2H2O

H2O2 comes from respiratory burst or from invading organisms

Front 153

What does catalase do?

Back 153

Catalase uses GSH to reduce H2O2 to H2O (and GSSG)

Catalase positive organisms neutralize their own H2O2 (bad for patients with CGD)

Front 154

Signs of ammonia intoxication?

Back 154

Tremor, Slurring of speech, Somnolence, Vomiting, Cerebral Edema, Blurred Vision

Front 155

Which amino acids are required during periods of growth?

Back 155

His, Arg

Front 156

PNMT catalyzes what reaction?

Back 156

NE --> Epi

Stimulated by cortisol from venous drainage from adrenal cortex through medulla.

Front 157

B6 is required for amino acid conversions into what?

Back 157

Tryptophan --> Niacin
Histidine --> Histamine
Glycine --> porphyrin
Glutamate --> GABA

Front 158

Pathway from glucose to glycogen?

Back 158

Glucose-6-phosphate --> glucose-1-phosphate --> UDP-glucose --> glycogen

Front 159

Glycogen phosphorylase: active in phosphorylated or dephosphorylated state?

Back 159

Active when phosphorylated --> glycogenolysis

Intracellular Ca/calmodulin phosphorylates glycogen phosphorylase kinase which phosphorylates glycogen phosphorylase

Front 160

What 2 factors increase cAMP to stimulate glycogenolysis?

Back 160

Glucagon (liver) and Epinephrine (liver and muscle)
--> Effect is to activate PKA which phosphorylates glycogen phosphorylase kinase

Insulin leads to activation of protein phosphatase.

Front 161

Cause of cystinuria?

Back 161

Hereditary defect of renal tubular amino acid transporter for cysteine, ornithine, lysine, and arginine in the PCT of the kidneys.

Front 162

Cystine kidney stones and treatment?

Back 162

Cystine staghorn calculi. Hexagonal in shape.

Treat with acetazolamine to alkalinize the urine.

Front 163

Findings in alkaptonuria (ochronosis)?

Back 163

Dark connective tissue, brown pigmented sclera, urine that turns black on standing, debilitating arthralgias.

Caused by homogentisic acid oxidase deficiency --> buildup of homogentisate

Front 164

Von Gierke's vs Cori's disease?

Back 164

Cori's: milder form of Von Gierke's
- gluconeogenesis is still intact because glucose-6-phosphatase is intact
- defect is debranching enzyme (alpha-1,6-glucosidase)

Front 165

Muscle cramps but no lactic acid with exercise. Disease?

Back 165

McArdle's disease (type V glycogen storage disease)
- deficient skeletal muscle glycogen phosphorylase (myophosphorylase)

Front 166

At what point do ketone bodies become the main source of energy for the brain and heart?

Back 166

After 3rd day of starvation
- amount of adipose store determines survival time

Front 167

HMG CoA reductase reaction?

Back 167

HMG CoA to mevalonate

2/3 of plasma cholesterol ends up being esterified by lecithin-cholesterol acyltransferase (LCAT)

Front 168

What are ketone bodies made from and metabolized to?

Back 168

Made from HMG CoA

Metabolized by brain to 2 molecules of acetyl CoA

Front 169

Deficiency of carnitine results in what?

Back 169

Inability to transport LCFAs into mitochondria --> results in toxic accumulation.

Causes weakness, hypotonia, and hypoketotic hypoglycemia.

Front 170

Changes in acyl-CoA dehydrogenase deficiency?

Back 170

Increased dicarboxylic acids
Decreased glucose and ketones

Front 171

What does A-I apolipoprotein do?

Back 171

Activates LCAT

Front 172

What do apolipoproteins E3 and E4 do?

Back 172

VLDL and chylomicron remnant uptake

Front 173

What does HDL act as a repository for?

Back 173

ApoC and ApoE (needed for chylomicron and VLDL metabolism)

Front 174

Hepatic overproduction of VLDL causes what type of familial dyslipidemia?

Back 174

Type IV - hypertriglyceridemia

Front 175

LPL or altered apolipoprotein C-II cause what type of familial dyslipidemia?

Back 175

Type I - hyperchylomicronemia
- elevated chylomicrons
- causes pancreatitis, hepatosplenomegaly, eruptive/pruritic xanthomas

Front 176

Absent or decreased LDL receptors cause what type of familial dyslipidemia?

Back 176

Type IIa - familial hypercholesterolemia
- increased LDL/cholesterol
- causes atherosclerosis, tendon (Achilles) xanthomas, corneal arcus

Front 177

Beta-glucocerebrosidase deficiency causes buildup of what and what disease?

Back 177

Buildup of Glucocerebrosides

Gaucher's disease (most common sphingolipidosis)

Front 178

Alpha-galactosidase deficiency causes buildup of what and what disease?

Back 178

Ceramide trihexoside buildup

Fabry's disease (angiokeratoma corporis diffusum)

Front 179

Finding in Krabbe's disease and defect?

Back 179

Peripheral neuropathy, developmental delay, optic atrophy, globoid cells.

Deficient galactocerebrosidase --> buildup of galactocerebroside

Front 180

Findings in Hurler's syndrome?

Back 180

Developmental delay, gargoylism, airway obstruction, corneal clouding, short neck, CAD, hepatosplenomegaly

Front 181

Enzyme deficiency in Hurler vs Hunter's syndrome?

Back 181

Hurler's: alpha-L-iduronidase

Hunter's: iduronate sulfatase

Front 182

Metachromatic leukodystrophy?

Back 182

Central and peripheral demyelination with ataxia & dementia.

Deficient arylsulfatase A leads to buildup of cerebroside sulfate (sulfatides)