Biochemistry flashcards for NEET PG
78 cards. Read the question, answer in your head, then check. For spaced repetition, study the deck in the app.
What this deck is for
These 78 cards pick out single facts in Biochemistry that the exam keeps returning to: Carbohydrate metabolism, Nucleotide metabolism, Vitamins, Lipid metabolism, Glycogen storage diseases, Amino acid metabolism and more. Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Cards are a starting set, not full coverage of the subject; the study guide lists the full map.
Where students slip in Biochemistry: Learning pathways as diagrams with no sense of which step is controlled. Read the Biochemistry study guide.
1 · Carbohydrate metabolism
Rate-limiting enzyme of glycolysis?
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Phosphofructokinase-1.
Memory hook: Activated by AMP and F-2,6-BP, inhibited by ATP and citrate.
2 · Nucleotide metabolism
Enzyme deficient in Lesch–Nyhan syndrome, and its inheritance?
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HGPRT; X-linked recessive. Self-mutilation, dystonia, high uric acid.
Memory hook: No salvage, so more uric acid.
3 · Vitamins
How do you tell B12 from folate deficiency biochemically?
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Methylmalonic acid is raised in B12 deficiency only; homocysteine is raised in both.
Memory hook: B12 also brings neurological signs.
4 · Lipid metabolism
Rate-limiting enzyme of cholesterol synthesis and its drug?
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HMG-CoA reductase; inhibited by statins.
Memory hook: Statins are the 'reductase' blockers.
5 · Glycogen storage diseases
Enzyme deficient in von Gierke disease?
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Glucose-6-phosphatase: fasting hypoglycaemia, big liver, lactic acidosis, high uric acid.
Memory hook: Type I: can't release glucose.
6 · Carbohydrate metabolism
Which enzyme is deficient in classic galactosaemia?
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Galactose-1-phosphate uridyltransferase: jaundice, cataracts and liver disease after milk feeds.
Memory hook: Stop galactose, stop the damage.
7 · Vitamins
Which vitamin deficiency causes pellagra, and what are the classic features?
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Niacin; dermatitis, diarrhoea and dementia.
Memory hook: The three Ds.
8 · Amino acid metabolism
Which amino acid is the precursor of serotonin and niacin?
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Tryptophan.
Memory hook: Hartnup disease and carcinoid can cause niacin deficiency.
9 · Carbohydrate metabolism
Which enzyme is rate-limiting in gluconeogenesis?
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Fructose-1,6-bisphosphatase, opposing PFK-1 of glycolysis.
Memory hook: Reciprocal regulation with glycolysis.
10 · Molecular biology
What does 'degenerate' mean for the genetic code?
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More than one codon can code for the same amino acid.
Memory hook: Not ambiguous: each codon codes for only one.
11 · Biomolecules and enzymes
What happens to Km and Vmax in competitive inhibition?
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Km rises and Vmax is unchanged, because excess substrate can outcompete the inhibitor.
Memory hook: Competitive: Km up, Vmax same.
12 · Biomolecules and enzymes
What happens to Km and Vmax in non-competitive inhibition?
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Vmax falls and Km is unchanged.
Memory hook: Non-competitive: Vmax down, Km same.
13 · Biomolecules and enzymes
What does a low Km indicate about an enzyme?
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High affinity for its substrate: half-maximal velocity is reached at a low substrate concentration.
Memory hook: Low Km, high affinity.
14 · Biomolecules and enzymes
Which CK isoenzyme is most specific for myocardium?
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CK-MB.
Memory hook: M for muscle, B for brain, MB for heart.
15 · Biomolecules and enzymes
What is the defect in collagen in scurvy?
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Failure of hydroxylation of proline and lysine because vitamin C is a cofactor for the hydroxylases.
Memory hook: Vitamin C hydroxylates collagen.
16 · Biomolecules and enzymes
Which collagen type is the main one in bone, skin and tendon?
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Type I.
Memory hook: Type I: bone.
17 · Biomolecules and enzymes
Which collagen type is defective in vascular Ehlers-Danlos syndrome?
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Type III.
Memory hook: Type III: vessels and gut (reticulin).
18 · Vitamins and minerals
Which vitamin deficiency causes night blindness and why?
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Vitamin A; 11-cis-retinal is needed to form rhodopsin in rod cells.
Memory hook: Night blindness is the earliest symptom.
19 · Vitamins and minerals
Which mineral deficiency causes microcytic anaemia, and which protein stores it?
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Iron; it is stored as ferritin and transported by transferrin.
Memory hook: Low ferritin is the earliest marker.
20 · Carbohydrate metabolism
Which enzyme is the rate-limiting step of the HMP (pentose phosphate) shunt?
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Glucose-6-phosphate dehydrogenase, which produces NADPH.
Memory hook: HMP shunt makes NADPH and ribose.
21 · Carbohydrate metabolism
What precipitates haemolysis in G6PD deficiency, and what is seen on the smear?
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Oxidant stress (infections, fava beans, certain drugs); Heinz bodies and bite cells.
Memory hook: No NADPH, no reduced glutathione.
22 · Carbohydrate metabolism
Which enzyme is the rate-limiting step of glycogen synthesis?
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Glycogen synthase.
Memory hook: Activated by insulin.
23 · Carbohydrate metabolism
Which enzyme is the rate-limiting step of glycogenolysis, and what is its cofactor?
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Glycogen phosphorylase, with pyridoxal phosphate (vitamin B6).
Memory hook: Phosphorylase needs B6.
24 · Carbohydrate metabolism
Which glycogen storage disease is due to deficiency of muscle glycogen phosphorylase?
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McArdle disease (type V): exercise intolerance, cramps and no rise in lactate.
Memory hook: Mc-Ardle: muscle.
25 · Carbohydrate metabolism
Which enzyme is deficient in Pompe disease, and where is the glycogen stored?
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Lysosomal acid alpha-1,4-glucosidase (acid maltase); glycogen accumulates in lysosomes, causing cardiomegaly.
Memory hook: Pompe: lysosome and heart.
26 · Carbohydrate metabolism
Which enzyme is deficient in Cori disease (type III)?
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Debranching enzyme (alpha-1,6-glucosidase); abnormal limit dextrin accumulates.
Memory hook: Cori: limit dextrin, normal lactate.
27 · Carbohydrate metabolism
Which gluconeogenic enzyme in the mitochondria needs biotin?
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Pyruvate carboxylase, which converts pyruvate to oxaloacetate and is activated by acetyl-CoA.
Memory hook: Biotin carboxylase step.
28 · Carbohydrate metabolism
Which enzyme complex is deficient in thiamine deficiency to cause lactic acidosis?
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Pyruvate dehydrogenase complex, which requires thiamine pyrophosphate.
Memory hook: TPP, lipoate, CoA, FAD, NAD.
29 · Carbohydrate metabolism
What is the net ATP yield of anaerobic glycolysis per glucose?
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2 ATP (4 produced, 2 used).
Memory hook: Anaerobic: net 2.
30 · Carbohydrate metabolism
Which enzyme in RBC glycolysis forms 2,3-BPG, and what does it do to oxygen affinity?
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Bisphosphoglycerate mutase; 2,3-BPG lowers haemoglobin's oxygen affinity (right shift).
Memory hook: More BPG, more O2 release.
31 · Carbohydrate metabolism
Which enzyme is deficient in hereditary fructose intolerance?
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Aldolase B; fructose-1-phosphate accumulates, causing hypoglycaemia and liver injury after fructose or sucrose intake.
Memory hook: Trapped phosphate, low glucose.
32 · Lipid metabolism
Which enzyme is the rate-limiting step of fatty acid synthesis?
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Acetyl-CoA carboxylase, which needs biotin and is activated by insulin and citrate.
Memory hook: ACC: biotin.
33 · Lipid metabolism
Which enzyme is the rate-limiting step of fatty acid oxidation (carnitine shuttle)?
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Carnitine palmitoyltransferase-I (CPT-I), inhibited by malonyl-CoA.
Memory hook: Malonyl-CoA blocks CPT-I.
34 · Lipid metabolism
Which organelle carries out beta-oxidation of very long chain fatty acids, and which disease is the classic defect?
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Peroxisomes; X-linked adrenoleukodystrophy is the classic disorder.
Memory hook: VLCFA accumulate.
35 · Lipid metabolism
Which lipoprotein carries dietary triglyceride from the intestine?
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Chylomicrons.
Memory hook: Exogenous fat.
36 · Lipid metabolism
Which apolipoprotein of LDL binds the LDL receptor?
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Apo B-100.
Memory hook: B-100 for LDL and VLDL; B-48 for chylomicrons.
37 · Lipid metabolism
Which lipid disorder shows tendon xanthomas and raised LDL due to a defective LDL receptor?
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Familial hypercholesterolaemia (type IIa).
Memory hook: Tendon xanthoma, early MI.
38 · Lipid metabolism
Which lipid-storage disease gives a cherry-red spot and no hepatosplenomegaly, due to hexosaminidase A deficiency?
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Tay-Sachs disease.
Memory hook: Tay-Sachs: no organomegaly.
39 · Lipid metabolism
Which enzyme is deficient in Gaucher disease, and what are the characteristic cells?
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Glucocerebrosidase (beta-glucosidase); macrophages with a crumpled tissue-paper cytoplasm.
Memory hook: Gaucher: bone pain, big spleen.
40 · Lipid metabolism
Which enzyme is deficient in Fabry disease, and what is its inheritance?
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Alpha-galactosidase A; X-linked recessive, with renal failure and painful neuropathy.
Memory hook: Fabry: X-linked, kidney.
41 · Amino acid metabolism
Which enzyme is deficient in classic phenylketonuria?
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Phenylalanine hydroxylase, with BH4 as cofactor.
Memory hook: Tyrosine becomes essential.
42 · Amino acid metabolism
What urine odour is typical of untreated phenylketonuria?
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Mousy or musty odour from phenylacetate.
Memory hook: Mousy smell.
43 · Amino acid metabolism
Which enzyme is deficient in alkaptonuria and what is the key finding?
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Homogentisate oxidase; urine darkens on standing and cartilage turns blue-black (ochronosis).
Memory hook: Dark urine, ochronosis, arthritis.
44 · Amino acid metabolism
Which enzyme is deficient in albinism?
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Tyrosinase (oculocutaneous albinism type 1).
Memory hook: No melanin from tyrosine.
45 · Amino acid metabolism
Which enzyme is deficient in classic homocystinuria?
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Cystathionine beta-synthase (some patients respond to pyridoxine); features are ectopia lentis (downward), thrombosis and intellectual disability.
Memory hook: Lens dislocates down in homocystinuria; up in Marfan.
46 · Amino acid metabolism
Which amino acids accumulate in maple syrup urine disease?
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Branched-chain amino acids (leucine, isoleucine, valine), due to branched-chain alpha-ketoacid dehydrogenase deficiency.
Memory hook: Treat with thiamine trial and diet.
47 · Amino acid metabolism
Which is the rate-limiting enzyme of the urea cycle and what activates it?
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Carbamoyl phosphate synthetase I, activated by N-acetylglutamate.
Memory hook: CPS-I is mitochondrial.
48 · Amino acid metabolism
Which urea cycle disorder is X-linked, and what is raised in urine?
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Ornithine transcarbamylase deficiency; orotic acid is raised in urine with high ammonia.
Memory hook: Only X-linked urea cycle defect.
49 · Amino acid metabolism
Which amino acids are purely ketogenic?
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Leucine and lysine.
Memory hook: Leu and Lys.
50 · Amino acid metabolism
Which amino acid is the main carrier of nitrogen from muscle to liver?
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Alanine (glucose-alanine cycle); glutamine carries nitrogen from most tissues.
Memory hook: Muscle: alanine; others: glutamine.
51 · Nucleotide metabolism
Which enzyme is the rate-limiting step of purine synthesis?
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PRPP amidotransferase (glutamine-PRPP amidotransferase).
Memory hook: Inhibited by AMP, GMP, IMP.
52 · Nucleotide metabolism
Which enzyme does allopurinol inhibit?
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Xanthine oxidase, reducing uric acid formation.
Memory hook: Xanthine oxidase makes urate.
53 · Nucleotide metabolism
Which enzyme deficiency causes severe combined immunodeficiency through accumulation of dATP?
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Adenosine deaminase deficiency.
Memory hook: ADA: SCID.
54 · Nucleotide metabolism
What is raised in urine in orotic aciduria and which enzyme is lacking?
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Orotic acid; UMP synthase (orotate phosphoribosyltransferase and OMP decarboxylase) is defective, with megaloblastic anaemia unresponsive to B12 or folate.
Memory hook: Treat with uridine.
55 · Vitamins and minerals
Which vitamin deficiency causes Wernicke encephalopathy?
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Thiamine (B1): confusion, ophthalmoplegia and ataxia.
Memory hook: Give thiamine before glucose.
56 · Vitamins and minerals
Which enzyme assay is used to assess thiamine status?
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Erythrocyte transketolase activity.
Memory hook: TPP is its cofactor.
57 · Vitamins and minerals
Which vitamin deficiency causes cheilosis and angular stomatitis, and what is its coenzyme?
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Riboflavin (B2); coenzymes FAD and FMN.
Memory hook: Flavin enzymes.
58 · Vitamins and minerals
Which vitamin is needed for gamma-carboxylation of glutamate residues in clotting factors?
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Vitamin K.
Memory hook: Factors II, VII, IX, X.
59 · Vitamins and minerals
Which drug is antagonised by vitamin K to reverse its action?
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Warfarin, which inhibits vitamin K epoxide reductase.
Memory hook: Vitamin K reverses warfarin.
60 · Vitamins and minerals
Which vitamin deficiency presents with rickets in children and osteomalacia in adults?
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Vitamin D (calcitriol deficiency).
Memory hook: Soft bones.
61 · Vitamins and minerals
Which form of vitamin D is the active hormone and where is it made?
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1,25-dihydroxycholecalciferol (calcitriol), made by 1-alpha-hydroxylase in the kidney.
Memory hook: Liver 25-OH, kidney 1,25-OH.
62 · Vitamins and minerals
Which vitamin is the cofactor for transaminases and what drug causes its deficiency?
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Pyridoxine (B6); isoniazid causes deficiency, so supplement it.
Memory hook: INH: give B6.
63 · Vitamins and minerals
Which copper transport disorder is X-linked and gives kinky hair?
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Menkes disease: ATP7A defect, causing copper deficiency.
Memory hook: Menkes: kinky hair, low copper.
64 · Vitamins and minerals
What is the defect in Wilson disease and the ocular sign?
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ATP7B defect with impaired biliary copper excretion and low ceruloplasmin; Kayser-Fleischer ring.
Memory hook: Wilson: copper excess.
65 · Molecular biology and genetics
Which enzyme synthesises RNA primer in DNA replication?
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Primase, a type of RNA polymerase.
Memory hook: Primer comes first.
66 · Molecular biology and genetics
Which is the main replicating enzyme in prokaryotes and which removes the primer?
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DNA polymerase III replicates; DNA polymerase I removes the primer and fills the gap.
Memory hook: Pol III leads, Pol I cleans.
67 · Molecular biology and genetics
Which enzyme relieves supercoiling ahead of the replication fork and which drug class inhibits it in bacteria?
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Topoisomerase (DNA gyrase in bacteria); inhibited by fluoroquinolones.
Memory hook: Gyrase: quinolones.
68 · Molecular biology and genetics
Which DNA repair pathway is defective in xeroderma pigmentosum?
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Nucleotide excision repair.
Memory hook: UV thymine dimers.
69 · Molecular biology and genetics
Which DNA repair pathway is defective in Lynch syndrome?
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Mismatch repair.
Memory hook: MSH2, MLH1.
70 · Molecular biology and genetics
Which RNA polymerase in eukaryotes transcribes mRNA?
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RNA polymerase II, which is inhibited by alpha-amanitin.
Memory hook: Mushroom poison.
71 · Molecular biology and genetics
Which three post-transcriptional modifications give a mature eukaryotic mRNA?
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5' capping, 3' poly-A tailing and splicing.
Memory hook: Cap, tail, splice.
72 · Molecular biology and genetics
Which antibiotic inhibits the 30S subunit and which inhibits the 50S subunit?
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Aminoglycosides and tetracyclines act on 30S; macrolides, chloramphenicol and clindamycin act on 50S.
Memory hook: 30S: AT; 50S: CCEL.
73 · Molecular biology and genetics
What is the start codon and which amino acid does it code in eukaryotes?
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AUG codes for methionine.
Memory hook: Stop: UAA, UAG, UGA.
74 · Clinical biochemistry
Which enzyme is preferred over amylase for diagnosing acute pancreatitis?
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Lipase, which is more specific than amylase and stays raised longer.
Memory hook: Lipase is more specific.
75 · Clinical biochemistry
Which cardiac marker is preferred for diagnosing acute myocardial infarction?
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Troponin I or T.
Memory hook: Rises in 3-6 hours.
76 · Clinical biochemistry
Which cardiac marker is best for detecting reinfarction?
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CK-MB, because it returns to baseline in about 2-3 days.
Memory hook: Short-lived.
77 · Clinical biochemistry
What does a raised anion gap metabolic acidosis suggest and how is anion gap calculated?
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Unmeasured acids such as lactate or ketones; anion gap = Na minus (Cl + HCO3).
Memory hook: MUDPILES.
78 · Clinical biochemistry
What does a raised HbA1c reflect?
Show the answer
Average blood glucose over the preceding 2-3 months, due to glycation of haemoglobin.
Memory hook: Red cell life span.
Common questions
How many Biochemistry flashcards are there?
78 cards across 11 topics. The deck grows as we add material.
Which topics are in the Biochemistry deck?
Carbohydrate metabolism, Nucleotide metabolism, Vitamins, Lipid metabolism, Glycogen storage diseases, Amino acid metabolism, Molecular biology, Biomolecules and enzymes, Vitamins and minerals, Molecular biology and genetics, Clinical biochemistry.
Is the Biochemistry deck free?
Yes. Biochemistry is one of the three decks open on the free plan, with Anatomy, Physiology and Biochemistry.
How do spaced-repetition cards work?
You rate each card Again, Hard, Good or Easy. Cards you find hard return soon and cards you know return later, so your time goes where you forget.
What is the memory hook on a card?
78 of these cards carry a one-line hook: a short cue that helps the answer stick. It is optional and appears after you reveal the answer.
How many Biochemistry cards should I do a day?
Ten to twenty minutes a day is plenty. A few due cards every day beat a long session once a week.
Can I flip through the cards on this page?
You can read each question and reveal its answer here. For scheduling, ratings and progress, study the deck in the app.
Are the Biochemistry cards reviewed by faculty?
Not yet. They are original and still awaiting independent review, so confirm anything important in a standard textbook.