High-Yield Exam Mnemonics
- “Lysosomes Lyse” (break down).
Recall: Lysosomes contain acid hydrolases that digest cellular debris and foreign material.
- Mitochondria were once independent bacteria (endosymbiotic theory).
Recall: Mitochondria have their own circular DNA and double membrane (outer and inner with cristae).
- G1 = Growth 1 = Greatest duration.
Recall: G1 phase is typically the longest, involving cell growth and preparation for DNA synthesis.
- Mitosis = Makes Two Identical cells.
Recall: Mitosis produces two genetically identical diploid daughter cells from one parent cell.
- Meiosis = Makes four gametes.
Recall: Meiosis produces four genetically distinct haploid gametes from one diploid parent cell.
- Sertoli Sustain Sperm.
Recall: Sertoli cells (nurse cells) nourish and support developing spermatocytes.
- Leydig = libido (testosterone).
Recall: Leydig cells (interstitial cells) in the testes produce testosterone under LH stimulation.
- One Oocyte = One Ovum.
Recall: One primary oocyte produces one functional ovum and three polar bodies (which degenerate).
- Estrogen = Endometrial growth.
Recall: Estrogen from developing follicles stimulates endometrial proliferation and thickening.
- Secretory = Luteal (both post-ovulation).
Recall: The secretory (uterine) phase corresponds to the luteal (ovarian) phase, both dominated by progesterone from corpus luteum.
- Acrosome on Apex of sperm head.
Recall: The acrosome (cap over sperm head) releases hyaluronidase and acrosin enzymes to penetrate the corona radiata and zona pellucida.
- Back and Up is Best for Baby.
Recall: Normal implantation occurs in the upper posterior wall of the uterine body, which has optimal blood supply.
- Tubal = Typical ectopic location.
Recall: 95% of ectopic pregnancies occur in the fallopian tube, most commonly the ampulla.
- Endoderm = Inner tube lining.
Recall: Endoderm forms the epithelial lining of the GI tract, respiratory tract, and associated glands (liver, pancreas).
- Week 3 = Three germ layers.
Recall: Week 3 features gastrulation (formation of ectoderm, mesoderm, endoderm) and primitive streak formation.
- Week 4 = Four-chambered heart starts.
Recall: The primitive heart tube begins beating around day 22-23 (late week 3/early week 4), making it the first functional organ.
- Sagittal Splits Sides.
Recall: The sagittal plane divides the body into right and left portions.
- Carpals = Cuboid Short bones.
Recall: Carpals are short bones (cube-shaped) that provide stability with limited movement in the wrist.
- Scapula is flat like a Shoulder blade.
Recall: Scapula is a flat bone providing muscle attachment and protection.
- Pivot = turning the head ‘No’.
Recall: Pivot joints (atlantoaxial, proximal radioulnar) allow rotation around a longitudinal axis.
- Cardiac = Heart only.
Recall: Cardiac muscle (myocardium) is found only in the heart, featuring branched striated fibers with intercalated discs.
- Thymus Trains T-cells.
Recall: The thymus is the site of T-lymphocyte maturation and selection.
- Peyer’s patches in the terminal ileum.
Recall: Peyer’s patches are aggregated lymphoid follicles in the ileum (terminal small intestine) on the antimesenteric border.
- Vagus = Vagabond parasympathetic.
Recall: The vagus nerve (CN X) carries parasympathetic fibers to thoracic and abdominal viscera (heart, lungs, GI tract to splenic flexure).
- Mucous = passages open to the world.
Recall: Mucous membranes line cavities that open to the exterior (respiratory, GI, urogenital tracts).
- Skin = Stratified Squamous for protection.
Recall: Stratified squamous epithelium (keratinized in skin, non-keratinized in oral cavity/esophagus) protects against abrasion.
- Transitional = stretchable for urine storage.
Recall: Transitional epithelium (urothelium) lines the urinary tract (bladder, ureters, renal pelvis), allowing stretching.
- Laminin = Lamina foundation protein.
Recall: Laminin is a glycoprotein in the basal lamina that helps anchor epithelial cells via integrins.
- Red Marrow makes Red cells.
Recall: In adults, red bone marrow (in flat bones, vertebrae, proximal long bones) is the primary hematopoietic site.
- Lysosomes Lyse (break down) cellular waste.
Recall: Lysosomes contain acid hydrolases that break down macromolecules, damaged organelles, and pathogens.
- Osmosis = water follows solutes.
Recall: Osmosis is the passive movement of water toward higher solute concentration to equalize osmotic pressure.
- Deoxy-DNA; Ribo-RNA.
Recall: DNA contains deoxyribose (lacks 2′-OH group), while RNA contains ribose.
- tRNA Transports amino acids.
Recall: Transfer RNA (tRNA) carries specific amino acids to ribosomes, recognizing mRNA codons via anticodons. mRNA carries genetic code. rRNA forms ribosome structure. snRNA is involved in splicing.
- Polymerase builds 5 to 3 (like reading left to right).
Recall: DNA polymerase adds nucleotides only to the 3′-OH end, synthesizing in 5′ to 3′ direction.
- Bicarbonate in Blood (both start with B).
Recall: Bicarbonate buffer (H₂CO₃/HCO₃⁻) is the main extracellular buffer, regulated by lungs (CO₂) and kidneys (HCO₃⁻).
- pKa = 50/50 split between acid and base forms.
Recall: At pH = pKa, the Henderson-Hasselbalch equation shows log(1) = 0, meaning [acid] = [conjugate base].
- Sucrose = Sugar on your table.
Recall: Sucrose (glucose + fructose) is table sugar from sugarcane/beets.
- Cellulose = Cannot digest; provides fiber.
Recall: Cellulose has β-1,4-glycosidic bonds that human enzymes cannot hydrolyze (we lack cellulase).
- Enzymes are Proteins that catalyze reactions.
Recall: Most enzymes are proteins (some are RNA = ribozymes).
- Lock-Key = perfect pre-existing fit, like a Key in a Lock.
Recall: Lock and key model (Fischer) proposes rigid complementary shapes between enzyme (lock) and substrate (key).
- Km = substrate concentration at 1/2 max speed.
Recall: Km equals substrate concentration when reaction velocity is half of Vmax (V = Vmax/2).
- TransFERRIN TransFERs iron.
Recall: Transferrin is the plasma protein that transports iron (2 Fe³⁺ ions per molecule) to tissues.
- ALA synthase = Always the Limiting enzyme (first and rate-limiting).
Recall: ALA synthase (δ-aminolevulinic acid synthase) is the rate-limiting enzyme, catalyzing glycine + succinyl-CoA → ALA.
- BiliRubin = Red-yellow pigment causing jaundice (Rubrum = red in Latin).
Recall: Heme → biliverdin (green) → bilirubin (yellow).
- GluVs = Glutamic acid replaced by Valine causes Sickling.
Recall: In sickle cell disease, glutamic acid at position 6 of β-chain is replaced by valine (GAG→GTG mutation).
- A for Adult = Alpha-Beta (α₂β₂).
Recall: HbA (97% of adult hemoglobin) = α₂β₂.
- Cysteine = Creates disulfide bridges (both start with C).
Recall: Cysteine has a thiol (-SH) group that forms disulfide bonds (Cys-S-S-Cys), stabilizing protein structure.
- Isoelectric = Equal charges (iso = equal), net zero.
Recall: At pI, the amino acid exists as a zwitterion with equal positive and negative charges (net charge = 0).
- IgG = Generally most abundant.
Recall: IgG is most abundant (~75-80% of serum immunoglobulins), crosses placenta, and provides long-term immunity.
- Crenation = Concentrated solution outside = Cell shrinks.
Recall: Crenation (shrinkage with spiky projections) occurs when cells are placed in hypertonic solutions–water moves out by osmosis.
- K⁺ keeps it negative; block K⁺ = less negative.
Recall: Potassium leak channels allow K⁺ efflux, maintaining the negative resting potential (around -70mV).
- High K⁺ outside = gradient drops = potential rises (less negative).
Recall: The Nernst equation shows that equilibrium potential depends on the ion concentration gradient.
- Actin ACTS at the front to push forward.
Recall: Amoeboid movement relies on actin polymerization (assembly) at the leading edge, pushing the membrane forward as pseudopodia.
- Spleen = RBC cemetery; macrophages are the undertakers.
Recall: Old RBCs are removed by macrophages of the reticuloendothelial system primarily in the spleen (major) and liver.
- No kidney function = No EPO = No RBC production signal.
Recall: Damaged kidneys produce insufficient erythropoietin (EPO), reducing bone marrow stimulation.
- Altitude = Appropriate response = Secondary polycythemia.
Recall: High altitude causes chronic hypoxia, stimulating appropriate EPO increase from kidneys–this is physiological secondary polycythemia.
- Eosinophils = worms and wheals (parasites and allergies).
Recall: Eosinophils are primary defense against parasites (helminths) and are elevated in allergies.
- Monocytes = Mobile precursors → Macrophages in tissues.
Recall: Monocytes differentiate into tissue macrophages (Kupffer cells, alveolar macrophages, microglia) and dendritic cells.
- More blood = Red and hot.
Recall: Vasodilation increases blood flow to the area, causing redness (rubor) and warmth (calor).
- Chronic = Changed from neutrophils to Macrophages and Lymphocytes.
Recall: Chronic inflammation features macrophages, lymphocytes, and plasma cells (mononuclear cells).
- Missing MHC I = Missing self = NK attacks.
Recall: NK cells have inhibitory receptors for MHC Class I.
- Second time = Stronger, Swifter, and IgG.
Recall: Secondary/anamnestic response is faster (memory cells activated), produces higher titers of high-affinity IgG (affinity maturation).
- MAC = Makes A Channel (pore in membrane).
Recall: MAC (C5b-C9) forms a transmembrane pore causing osmotic lysis–C9 polymerizes to form the actual pore.
- C3 = Convergence point; all roads lead to C3.
Recall: All three pathways generate C3 convertase, which cleaves C3 into C3a and C3b–the central amplification step.
- Type III = Immune complex disease (III looks like bundles/complexes).
Recall: Type III hypersensitivity involves antigen-antibody (immune) complex deposition in tissues, activating complement and causing inflammation (SLE nephritis).
- Five (V) helps with prothrombin conversion.
Recall: Factor Va is the essential cofactor in the prothrombinase complex (Xa + Va + Ca²⁺ + phospholipid) that converts prothrombin to thrombin.
- tPA = Tissue (endothelial) Plasminogen Activator = main physiological.
Recall: Tissue plasminogen activator (tPA) from endothelium is the primary physiological activator of plasminogen.
- vWF = double duty: platelet glue + Factor VIII protector.
Recall: VWF both mediates platelet adhesion (primary hemostasis) AND stabilizes Factor VIII (prolongs its half-life). vWD affects both functions.
- Protein C Cuts the cofactors (Va, VIIIa).
Recall: Activated Protein C (APC) with Protein S as cofactor cleaves and inactivates Factor Va and VIIIa (cofactors that amplify coagulation).
- Fever without hemolysis = cytokines from storage.
Recall: Febrile non-hemolytic reactions result from cytokines (IL-1, IL-6, TNF) accumulated during storage or recipient antibodies against donor WBC antigens.
- “Iron Hearts the Liver and Hormones” (damages them).
Recall: Transfusional iron overload (hemosiderosis) deposits iron in heart (cardiomyopathy), liver (cirrhosis), and endocrine glands (diabetes, hypogonadism).
- HLA = Six (chromosome 6).
Recall: HLA genes are clustered on the short arm of chromosome 6 (6p21.3).
- A, B, DR = Always Be DRafting matches.
Recall: HLA-A, B (Class I) and HLA-DR (Class II) are most important for transplant matching–they are highly polymorphic and immunogenic.
- Right shift = Release oxygen readily.
Recall: Rightward shift = decreased affinity = hemoglobin releases O2 more readily (increased delivery).
- Passive = Passed to you (not made by you).
Recall: Maternal antibodies (IgG via placenta, IgA via breast milk) provide passive immunity–preformed antibodies without active immune response.
- High K⁺ outside = less K⁺ leaves = less negative inside.
Recall: Hyperkalemia reduces the concentration gradient for potassium across the cell membrane, diminishing K⁺ efflux and causing partial depolarization of the resting membrane potential (making it less negative).
- Plateau = Calcium in, Potassium out, Perfectly balanced.
Recall: The plateau phase (Phase 2) results from a balance between inward calcium current through L-type calcium channels and outward potassium current through delayed rectifier channels.
- Dynein DYNamically bends cilia using ATP.
Recall: Ciliary movement is powered by dynein ATPase, which causes sliding of adjacent microtubule doublets within the 9+2 axonemal structure.
- FIBroblasts in cortex FIBricate EPO.
Recall: Erythropoietin is produced primarily by peritubular interstitial fibroblasts (type I interstitial cells) in the renal cortex.
- B12 deficiency = Both Blood and Brain problems.
Recall: Terminal ileum disease causes B12 malabsorption (loss of intrinsic factor-B12 complex absorption).
- No CD18 = No sticking = No escape from blood vessels.
Recall: Leukocyte adhesion deficiency type 1 (LAD-1) results from CD18 deficiency, affecting LFA-1, Mac-1, and p150,95 integrins.
- Kupffer = Keeper of clean blood in liver.
Recall: Kupffer cells are hepatic macrophages that filter portal and systemic blood, removing bacteria and debris.
- BTK = B cell Tyrosine Kinase = Boys without B cells.
Recall: X-linked agammaglobulinemia (Bruton disease) results from BTK mutations preventing B cell maturation beyond the pre-B cell stage.
- Germinal centers = Gym for B cells to get STRONGER and SWITCH.
Recall: During primary response, activated B cells in germinal centers undergo somatic hypermutation (increasing affinity) and class switching (producing IgG instead of IgM).
- HAE = Hereditary Angioedema = BradyKinin gone wild.
Recall: Hereditary angioedema results from C1-inhibitor deficiency.
- Type I = IgE on FcεRI on mast cells = Immediate reaction.
Recall: Type I hypersensitivity involves IgE antibodies bound to high-affinity FcεRI receptors on mast cells and basophils.
- GP Ib = Initiate Binding (through VWF).
Recall: GP Ib-IX-V (specifically GP Ibα) binds to VWF A1 domain, which is bound to exposed collagen.
- Dense granules = Dense with small molecules (ADP, ATP, Ca, serotonin).
Recall: Dense granules contain small molecules: ADP (platelet activator), ATP, serotonin (vasoconstrictor), and calcium (essential for coagulation).
- DIC = Disseminated Intravascular Coagulation = Thrombin gone wild.
Recall: DIC is characterized by systemic thrombin generation causing widespread microvascular thrombosis and consumption of platelets, fibrinogen, and coagulation factors.
- Hemophilia A = fActor Eight deficiency.
Recall: Hemophilia A is X-linked factor VIII deficiency presenting with hemarthroses, deep tissue bleeding, prolonged aPTT (intrinsic pathway), and normal PT.
- Factor V Leiden = Leiden to APC cleavage = APC Resistance.
Recall: Factor V Leiden has an arginine-to-glutamine substitution at position 506, the primary APC cleavage site.
- aPL = prolonged aPTT in Lab but Thrombosis in Life.
Recall: Antiphospholipid antibodies cause thrombosis through multiple mechanisms: activating endothelial cells to express tissue factor, displacing annexin V from phospholipid surfaces (exposing procoagulant phosphatidylserine), inhibiting protein C activation, and activating platelets and complement.
- O negative = Universal donor; protect Rh-negative women from sensitization.
Recall: If type O Rh-negative is unavailable, type O Rh-positive may be considered in emergencies, but for an Rh-negative woman of childbearing age, every effort should be made to find Rh-negative blood to prevent sensitization and future hemolytic disease of the newborn.
- TRALI = Trapped neutrophils in Lungs causing ALI.
Recall: TRALI is caused by donor antibodies (anti-HLA or anti-neutrophil) that activate recipient neutrophils in pulmonary microvasculature.
- Anemia → extramedullary erythropoiesis → liver dysfunction → low albumin + heart failure → hydrops.
Recall: Severe fetal anemia causes extramedullary hematopoiesis (liver, spleen), leading to hepatomegaly and impaired albumin synthesis (hypoalbuminemia, reduced oncotic pressure).
- TAP Transports peptides for class I presentation.
Recall: TAP (TAP1/TAP2 heterodimer) is an ABC transporter that translocates proteasome-generated peptides (typically 8-16 amino acids) from cytosol into ER, where they are loaded onto MHC class I molecules with help from tapasin.
- PRA = Pre-formed antibodies against HLA = Panel Reactivity against Alloantigens.
Recall: PRA measures pre-formed antibodies against HLA molecules, developed from prior transfusions, pregnancies, or transplants.
- MHC class II presents autoantigens → CD4+ activation → autoimmunity.
Recall: HLA class II molecules on APCs present islet cell autoantigens (insulin, GAD65) to CD4+ T helper cells.
- ADA deficiency = dATP Accumulation = DNA synthesis Death.
Recall: ADA deficiency leads to accumulation of deoxyadenosine, which is phosphorylated to dATP.
- Rough means Ribosomes.
Recall: Ribosomes attached to RER give it a “rough” appearance and synthesize proteins for secretion.