Mnemonic 1: Mendel's Three Laws (DSI)
"Dominant Students Independently succeed"
- Dominance → Law of Dominance (F1 shows only dominant trait)
- Segregation → Law of Segregation (alleles separate into gametes)
- Independent assortment → Law of Independent Assortment (genes on different chromosomes assort freely)
Order matters: Dominance was stated first, Segregation derived from monohybrid, Independent Assortment from dihybrid.
Mnemonic 2: ABO Blood Groups
"AB = All antigens, Blank antibodies. O = Zero antigens, bOth antibodies."
- AB: has BOTH A and B antigens; has NO antibodies → Universal Recipient
- O: has NO antigens; has BOTH anti-A and anti-B → Universal Donor
- A: has A antigen, anti-B antibody ("A person carries Anti-opposite — Anti-B")
- B: has B antigen, anti-A antibody ("B person carries Anti-opposite — Anti-A")
Mnemonic 3: Pleiotropy vs Polygenic
"PLEI = one gene, POLY = one trait"
- PLEIotropy: one gene produces pleios (many) effects/traits
- Polygenic: poly (many) genes produce ONE trait
Mnemonic 4: Mendel's Dominant Traits (TVRASIG)
"Tall Violets Run And Score Incredible Goals"
- Tall stem
- Violet flower colour
- Round seed shape
- Axial flower position
- Seed colour Yellow (S = Yellow is Strange recollection — use Yellow for Seeds)
- Inflated pod shape
- Green pod colour
Mnemonic 5: Modified Ratios (9-7-4-1-3)
"9 Clearly Powerful Dominant Interactions" for the numerators: 9, 3+3+1=7 (complementary), 9+3=12 (dominant epistasis), 15+1 (duplicate), 13+3 (inhibitory)
Easier: remember by class merging:
- 9:7 = Complementary (7 = all non-double-dominant merged)
- 12:3:1 = Dominant epistasis (12 = 9+3 with dominant inhibitor)
- 9:3:4 = Recessive epistasis (4 = 3+1 with recessive masker)
- 15:1 = Duplicate (15 = all with at least one dominant allele of either gene)
- 13:3 = Inhibitory (13 = all except iiC_, 3 = iiC_)
Mnemonic 6: Seed vs Pod Colour Trap
"Yellow Seeds, Green Pods — nature reverses the norm"
- Yellow SEEDS dominant (Green seed = recessive)
- GREEN PODS dominant (Yellow pod = recessive)