Usmle Biochemistry Questions

Front 1

A kid with PKU is deficient in what amino acid?

Back 1

* Tyrosine (Can't convert PHE to TYR)

Front 2

A kids with sublenticular bilateral cataracts with NO other abnormalities probably has:

Back 2

* Galactosemia (deficient galactokinase)

Front 3

Big side-effect to ALPHA 1 blockers:

Back 3

* Orthostatic hypotension (i.e. Terazosin)

Front 4

A pt with diarrhea, dermatitis, and dementia has:

Back 4

* Pellegra (Niacin deficiency)

Front 5

Metabolic acidosis can be caused by build up of lactic acid-- where would this occur in the cell?

Back 5

* In the cytoplasm

Front 6

Leukotrienes involved in ashtma are:

Back 6

* LT C4, D4, and E4

Front 7

What phase of the cell cycle does microtuble production occur?

Back 7

* G2 phase

Front 8

Cox-2 inhibitors have no effect on this product of aracadonic acid:

Back 8

* Thromboxanes

Front 9

With alcohol overdose what happens biochemically in the liver?

Back 9

* Overproduction of REDUCED NAD also known as NADH

Increased NADH/NAD+ ratio

Front 10

A pt who has uroporphorin in his tea-colored urine has a deficiency of:

Back 10

* Uropor decarboxylase (as seen with porphoryea cutanea tarda)

Front 11

Lead poisoning will lead to basophilic RBC stippling and deficiency of what enzyme:

Back 11

* ALA dehydrase leading to accumulation of ALA

Front 12

What is the rate limiting enzyme in de novo purine synthesis?

Back 12

Glutamine-PRPP amidotransferase. Found on pg. 91 (2008) and pg. 99 (2009).

Front 13

What is the rate limiting enzyme in glycogenolysis?

Back 13

Glycogen phosphorylase. Found on pg. 91 (2008) and pg. 99 (2009).

Front 14

What is the rate limiting enzyme in fatty acid synthesis?

Back 14

Acetyl-CoA carboyxlase. Found on pg. 91 (2008) and pg. 99 (2009).

Front 15

Pt with gargoylism, corneal clouding, high lysosomal enzymes has:

Back 15

* I-cell disease (problems with mannose-6-PO4 in the GOLGI)

Front 16

A kid with a X-linked trinuc repeat disorder with a big jaw and big balls has:

Back 16

* Fragile X (CGG trinuc repeat)

Front 17

What type of mutation causes Becker/Duchenne muscular dystrophy?

Back 17

* Frameshift mutation that deletes dystrophin

Front 18

When a Gs receptor is stimulated (such as B1/B2's) what happens to cAMP and ATP?

Back 18

* ATP is decreased (used up) and cAMP is made (increased)

Front 19

What happens when a Gq receptor (alpha1 and M1/M3) are stimulated?

Back 19

* Increased Ca2+ and Protein Kinase C (via the PIP-- DAG/IP3 pathway)

Front 20

Male or female who is infertile d/t immobile cilia (dynein arm defect) who present with brochiectasis, recurrent sinusitis, and possible situs invertus has:

Back 20

* Kartagener's syndrome (dyein arm defect)

Very similar to cystic fibrosis in presentation

Front 21

Any problem with Inrons think:

Back 21

* Splicing problem

Front 22

Trisomies occur d/t problems where in the cell cycle?

Back 22

* Due to non-disjunction during ANAPHASE I or ANAPHASE II

Front 23

2 biochem XR diseases:

Back 23

* Hunters and Fabrys

Front 24

Deficiency in Fabrys:

Back 24

* alpha-galctosidase A

Peripheral neuropathy, angiokeratomas, cardio/renal disease

Front 25

In AR Cystic Fibrosis, there is a DELETION on chromosome 7 of the Phe 508, what does this do to the CFTR protein?

Back 25

* Causes protein folding in the ER

Front 26

Arginine + aspartate + carbamoyl phosphate will produce:

Back 26

* Arginosuccinic acid

Front 27

Associated with Rb tumor suppressor:

Back 27

* Retinoblastoma, Osteosarcoma

Front 28

Associated with deletion of DPC:

Associated with deletion of DCC:

Back 28

* DPC (Deleted in Pancreatic Cancer)

DCC (Deleted in Colon Cancer)

Front 29

Cancers associated with a CEA tumor marker:

Back 29

* Pancreatic cancer and Colon cancer, sometimes also by gastric and breast cancers

Front 30

Associated with AFP tumor marker:

Back 30

* Yolk sac tumors and Hepatocellular carcinoma (HCC)

Front 31

Associated with CA-125 marker:

Back 31

* Ovarian, malignant epitheloid tumors

Front 32

Associated with TRAP (tartrate resistant acid phosphatase):

Back 32

* Hairy cell leukemia

Front 33

Associated with CA-19-9:

Back 33

* Pancreatic adenocarcinoma

Front 34

Markers associated with pancreatic cancers:

Back 34

* CA 19-9 and CEA

Front 35

Marfan sydrome affects:

Back 35

* Microfibrils/Myofibrils (d/t a defective fibrillin gene)

Marfan's is an AD disorder

Front 36

A girl who can't break down sucrose has a deficiency of:

Back 36

* Fructokinase-1-PO4-Aldolase

Front 37

High EtOH consumption makes these end products instead of these normal products:

Back 37

* High NADH makes LACTATE and MALATE instead of pyruvate and oxaloacetate

Front 38

Labile cells never go to this phase of the cell cycle:

Back 38

* G0 (they divide rapidly with a short G1)

Front 39

RBC's use this process for energy:

Back 39

* Glycolysis (deficiency of PYRUVATE KINASE will lead to hemolytic anemia)

Front 40

Any problem with the Urea cycle think this amino acid:

Back 40

* Arginine (converts ammonia to urea for excretion)

Front 41

A pt (adult/kid) with arthritis sx and urine that turns BLACK on standing think:

Back 41

* Onchronosis (Alkaptonuria)

Alkaptonuria is d/t accumulation of HOMEOGENTISIC ACID in the urine

Front 42

A kid with seizures, a severe hypoglycemia, and a hyperlipidemia think deficiency of:

Back 42

* Glucose-6-phosphatase deficiency (Von Gierkes disease)

Glycogen storage disease

Front 43

Deficient enzymes in the type I, II, III, and type V glycogen storage diseases:

Back 43

* Very Poor Carb Metabolism (Von Gierkes, Pompes, Cori's, McArdles)

is due to GLDS or (Glucose6P, Lysosomal alpha1/4, Debranching alpha 1/6, and Skeletal glycogen phosphorylase)

Front 44

Where do you find these amyloid types:

AA, ABeta, and AL?

Back 44

* AA = Kidney, Spleen, Liver (Secondary Amyloidosis)

ABeta = Alzheimers (Dementia)

AL = Heart/Kideny (Primary Amyloidosis) ATTR = cardiac

Front 45

Strenous activity lasting from a few seconds to a few minutes would use what fuel source?

Back 45

* Muscle glycogen

Front 46

What occurs in the golgi, RER, and smooth ER?

Back 46

* Golgi = packaging (like of man-6-P)

RER = protein destined for lysosomes

Smooth ER = Trig synthesis and protein destined for Peroxisomes

Front 47

Discuss pericentric and paracentric chromosomal inversion:

Back 47

* PERI-centric (Flipped over middle/Inverted chromosome) = Involve centromere and proceeds through miosis

PARA-centric = doesn't inolve either

Front 48

A kid with radio-opaque staghorn calculi in the renal pelvis and a diagnostic positive NITROPRUSS CYANIDE test has:

Back 48

* CYSTINURIA (AR inheritance)

Defective COLA (cysteine, ornithine, lysine, arginine) in the PCT of renals.

Leads to Staghorn calculi

Tx: Acetazolamide

Front 49

A kid with an sub-ependymal Astrocytoma might also have:

Back 49

* Cortical tubers

He has Tuberous Sclerosis (AD disorder) characterized by: CARRAH (cortical tubers, ash leaf spots, rhabdomyosarcomas, renal angiolypomas, ASTROCYTOMAS and HAMARTOMAS

Front 50

Best way to measure if someone is still drinking EtOH:

Back 50

* Measure GGTP (gamma glutamyl transpeptidase level)

Front 51

Body fuel when starving:

Back 51

1 -3 days = Hepatic Glycogen or Adipose FFA (to 4hrs diet carbs, 5 to 24hrs glycogenolysis, 25 - 36hrs = hepatic gluconeogensis)

4+ Days = Muscle protein

Weeks = Ketone bodies via fat

Front 52

Becker and Duchene are different because of what genetic change:

Back 52

* In-frame deletions/insertions in Becker (live longer) and frameshift deletions/insertions in Duchenne

Front 53

A micro-deletion in 15q11.2 is:

Back 53

* Prader-Willi (paternal) -- abnormal parent specific METHYLATION

Front 54

A kid with microcephaly, wide-set eyes, and mental retardation with a "cat cry" has:

Back 54

* Cru-du-chat (terminal deletion of 5p)

Front 55

Kid with high renin, but hypo-kalemia and increased bicarb think:

Back 55

* Bartters syndrome (hyper reninemia but angio II doesn't respond so there is low aldosterone)

Front 56

Only gastric hormone that inhibits gastric emptying:

Back 56

* CCK (from the I cells of duo/jejun)

Front 57

A pt with a deficient lipoprotein lipase would have eleveated ___ in his serum:

Back 57

* Chylomicrons

Front 58

Where in the cell is collagen made/processed:

Back 58

* Rough ER and Golgi

Front 59

XR disorder that is defective copper transport d/t ATP7 gene and LYSYL OXIDASE dysfunction:

Back 59

* Menkes disease

Copper, Lysl oxidase, ATP7

Front 60

Kid with blood in his urine and renal dysfunction think:

Back 60

* IgA nephritic syndrome (Berger's)

Front 61

A man whose dong culture shows "school of fish" pattern, gram neg rod, growns on chocalate agar, and requires protein V and X for growth is:

Back 61

* Haemophilus ducreyi (Chancre-- painful)

Gram-neg rod, requires the VX to grow

Front 62

A deletion by the father on chromosome 15 is an example of:

Back 62

* Imprinting (seen with Prader-Willi)

Front 63

What is the issue in Brutons Agammaglobulinemia:

Back 63

* Defective tyrosine kinase blocks B-cell maturation

Front 64

Finding in the urine of someone with carcinoid syndrome:

Back 64

* 5-HIAA

Front 65

Kid with a deficiency of Arylsulfatase A resulting in cerebroside sulfate has:

Back 65

* Metachromatic Leukodystrophy

M.A.C (Metachrom, Arylsulf, Cerbroside)

Front 66

Kid with optic atrophy and globoid cells:

Back 66

* Krabbes disease

Krabby Galactocerebro

Front 67

Kid with cherry-red spot on macula and foam cells:

Back 67

* Nieman Pick

Nieman Picks Sphingomyelin

Front 68

Kids the aseptic necrosis of the femur, and mac's that look like crumpled paper:

Back 68

* Gauchers

Gauch B-Glucocereb

Front 69

Kid with peripheral neuropathy, cardio/renal disease, and angiokeratomas:

Back 69

* Fabrys (alpha-galatosidase A-- accumulates ceramide tihexoside)

Fabry's a(lpha) galaxy of ceramide

Front 70

Kid with cat like cry, MR, and slant-eyes has:

Back 70

* Cru-du-chat (5p) and might have a VSD (cardiac defect)

Front 71

If a person consumes 25g of salt a day, how much is excreted?

Back 71

* 95% of salt intake is excreted so in this case 25 x .95 = 23g excreted

Front 72

A person with finger clubbing might have:

Back 72

* Lung cancer, liver cancer, or cyanotic heart disease