Biochemistry & Genetics confusion pairs
41 Biochemistry & Genetics topics students commonly mix up on Step 1, each with the fastest separator, a side-by-side comparison, and a free practice question.
- Glycolysis vs GluconeogenesisGlycolysis consumes glucose and uses PFK-1; gluconeogenesis makes glucose and bypasses irreversible steps with PC, PEPCK, F-1,6-BPase, and…Video
- Fed state vs Fasting stateFed state stores fuel through insulin; fasting state mobilizes fuel through glucagon, epinephrine, gluconeogenesis, lipolysis, and ketones.
- Von Gierke and Pompe glycogen storage diseases vs Cori, McArdle, Andersen, and Hers glycogen storage diseasesVon Gierke is severe fasting hypoglycemia; Pompe is cardiomyopathic lysosomal disease; McArdle is exercise muscle disease; Andersen is…
- GM2 and sphingomyelin lysosomal storage diseases vs Glucocerebrosidase, alpha-galactosidase, galactocerebrosidase, and mucopolysaccharide disordersTay-Sachs is GM2 neurodegeneration without hepatosplenomegaly; Niemann-Pick adds foam cells/hepatosplenomegaly; Gaucher is bone crises;…
- Tay-Sachs disease vs Niemann-Pick disease and Krabbe diseaseTay-Sachs is GM2 with no hepatosplenomegaly; Niemann-Pick is foam cells with hepatosplenomegaly; Krabbe is demyelinating globoid-cell…
- Hurler syndrome vs Hunter syndromeHurler has corneal clouding; Hunter has no corneal clouding and is X-linked with iduronate sulfatase deficiency.Video
- PKU and alkaptonuria vs Maple syrup urine disease and homocystinuriaPKU is musty phenylalanine toxicity; alkaptonuria is dark urine/ochronosis; MSUD is sweet branched-chain amino acids; homocystinuria is…
- Classic galactosemia vs Galactokinase deficiencyClassic galactosemia is sick infant with liver disease and E coli sepsis; galactokinase deficiency is mainly cataracts.
- Hereditary fructose intolerance vs Essential fructosuriaHereditary fructose intolerance is aldolase B toxicity with hypoglycemia; essential fructosuria is benign fructokinase loss.
- OTC deficiency vs Other urea cycle defectsOTC is hyperammonemia with high orotic acid and no megaloblastic anemia; other urea defects separate by…
- Vitamin A and D deficiency vs Vitamin E and K deficiencyA is eyes/epithelium; D is bone mineralization; E is neurologic/hemolysis; K is coagulation with prolonged PT.
- Thiamine and riboflavin deficiency vs Niacin and pyridoxine deficiencyB1 is Wernicke/beriberi; B2 is cheilosis/corneal vascularization; B3 is pellagra; B6 is sideroblastic anemia, neuropathy, and seizures.
- Vitamin B12 deficiency pattern vs Folate deficiency patternB12 and folate both cause megaloblastic anemia; B12 uniquely raises methylmalonic acid and causes neurologic disease.
- Wernicke encephalopathy vs BeriberiWernicke is brain triad from thiamine deficiency; beriberi is peripheral nerve or high-output heart failure from thiamine deficiency.
- Pellagra vs ScurvyPellagra is dermatitis-diarrhea-dementia; scurvy is defective collagen with bleeding gums, corkscrew hairs, and poor wound healing.
- Marasmus vs KwashiorkorMarasmus is total calorie wasting without edema; kwashiorkor is protein deficiency with edema and fatty liver.Video
- Carnitine deficiency vs MCAD and LCHAD deficienciesCarnitine deficiency is transport failure with muscle/cardiac lipid buildup; MCAD is fasting hypoketotic hypoglycemia; LCHAD adds…
- Mitochondrial inheritance vs Mendelian inheritanceMitochondrial disease is maternal-only transmission with heteroplasmy; Mendelian disease follows nuclear pedigree rules.
- Autosomal dominant inheritance vs Autosomal recessive inheritanceAutosomal dominant is vertical and one allele; autosomal recessive is sibling clustering from carrier parents and two alleles.
- X-linked recessive inheritance vs X-linked dominant inheritanceX-linked recessive is mostly males through carrier mothers; X-linked dominant makes all daughters of affected fathers affected and may…Video
- Nondisjunction aneuploidy vs Robertsonian translocation and mosaicismNondisjunction changes chromosome number; Robertsonian rearranges acrocentric long arms; mosaicism means two postzygotic cell lines.
- Trisomy 21 vs Trisomy 13 and trisomy 18Trisomy 21 is Down syndrome with duodenal/cardiac/Alzheimer risk; trisomy 13 is midline/polydactyly; trisomy 18 is clenched fists and…
- Klinefelter syndrome vs Turner, Triple X, and XYY syndromesKlinefelter is XXY hypogonadal male; Turner is short 45,X female; Triple X is tall female; XYY is tall male.
- DiGeorge syndrome vs Velocardiofacial syndrome and CATCH-22 framingDiGeorge spotlights thymus/parathyroid/T-cell hypocalcemia; velocardiofacial spotlights palate/facies/psychiatric features; both are…
- Marfan syndrome and homocystinuria vs Ehlers-Danlos and Loeys-Dietz syndromesMarfan is lens up/out and aortic root; homocystinuria is lens down/in and thrombosis; EDS is skin/joint collagen; Loeys-Dietz is bifid…
- Neurofibromatosis type 1 vs Neurofibromatosis type 2 and schwannomatosisNF1 is cafe-au-lait/neurofibromas/Lisch/optic glioma; NF2 is bilateral vestibular schwannomas; schwannomatosis is multiple painful…
- Tuberous sclerosis vs Sturge-Weber and Von Hippel-Lindau syndromesTuberous sclerosis is hamartomas with ash-leaf/seizures; Sturge-Weber is port-wine/leptomeningeal angioma; VHL is hemangioblastoma plus…
- Hereditary hemorrhagic telangiectasia vs Other vascular malformationsHHT is autosomal dominant epistaxis plus mucocutaneous telangiectasias and visceral AVMs; other malformations are usually localized or…
- Achondroplasia vs Osteogenesis imperfecta and hypochondroplasiaAchondroplasia is FGFR3 short-limb dwarfism; osteogenesis imperfecta is collagen brittle-bone disease; hypochondroplasia is milder FGFR3…
- Beckwith-Wiedemann syndrome vs Russell-Silver syndromeBeckwith-Wiedemann is 11p15 overgrowth with macroglossia/omphalocele/tumors; Russell-Silver is 11p15 growth restriction with triangular…Video
- Prader-Willi syndrome vs Angelman syndromePrader-Willi is paternal loss with hyperphagia/obesity/hypogonadism; Angelman is maternal loss with seizures/ataxia/happy affect.Video
- Fragile X syndrome vs Other intellectual disability syndromesFragile X is CGG-repeat FMR1 with long face, large ears, macroorchidism, and autism-like behavior; other ID syndromes need a different…
- Leading strand DNA replication vs Lagging strand DNA replicationLeading strand is continuous toward the fork; lagging strand is discontinuous Okazaki fragments sealed by ligase.
- Transcription vs TranslationTranscription: DNA to RNA by RNA polymerase in the nucleus; translation: mRNA to protein by ribosomes in the cytoplasm.
- mRNA vs tRNA and rRNAmRNA is the protein-coding template; tRNA is the charged adaptor; rRNA is the ribosomal catalyst/scaffold.
- Frameshift mutation vs Missense, nonsense, and silent mutationsFrameshift changes the downstream reading frame; missense changes one amino acid; nonsense creates stop; silent changes no amino acid.
- Splice site mutation vs Frameshift mutationSplice site mutation breaks RNA processing; frameshift mutation breaks codon grouping in the coding sequence.
- Mitochondrial-encoded genes vs Nuclear-encoded mitochondrial proteinsMitochondrial-encoded disease follows maternal heteroplasmy; nuclear-encoded mitochondrial disease follows Mendelian inheritance and…
- lac operon vs trp operonlac is inducible catabolism turned on by lactose and low glucose; trp is repressible biosynthesis turned off by abundant tryptophan.
- Cell-cycle checkpoint regulators vs Cell-cycle phase identificationCheckpoint regulators explain why the cell stops or proceeds; phase identification names where the cell is in the cycle.
- p53 tumor suppressor vs Rb tumor suppressorp53: senses DNA damage and triggers G1 arrest or apoptosis; Rb: binds E2F to block the G1/S transition until it is phosphorylated.Video