• The Jackson Laboratory (JAX): Founded in 1929 in Bar Harbor, Maine by Clarence Cook Little, The Jackson Laboratory is world-renowned as the premier repository and breeding center for inbred laboratory mouse strains (e.g., C57BL/6, BALB/c).
• Genetic Importance: Inbred strains ($F \gt 99\%$) provide genetically identical, homozygous animal models essential for biomedical research, cancer genetics, immunology, and mammalian genomics.
• Key Contributions: Over 26 Nobel Prizes are associated with mice developed or sourced from The Jackson Laboratory.

Correct option: (2) Inbred lab animals

• Missing Heritability: In Genome-Wide Association Studies (GWAS), statistically significant single nucleotide polymorphisms (SNPs) identified across the genome collectively explain only a modest fraction of the total phenotypic heritability ($h^2$) estimated from pedigree-based classical quantitative genetics. This discrepancy is termed the missing heritability problem.
• Underlying Causes:

• Numerous rare variants with large effect sizes that evade GWAS detection thresholds.
• Structural variants (CNVs, inversions, translocations).
• Epistatic gene-gene interactions and epigenetic modifications.
• Gene-environment ($G \times E$) interactions.
  
  Correct option: (3) Missing heritability

• Stop Codons (Termination Codons): In the standard genetic code, three codons do not encode any amino acid and serve as translational stop signals:

• UAA (Ochre)
• UAG (Amber)
• UGA (Opal)
  • Evaluation of Options:

• UAG: Amber stop codon.
• UAA: Ochre stop codon.
• Both UAG and UAA trigger release factors (RF1/RF2 in prokaryotes; eRF1 in eukaryotes) to hydrolyze the peptidyl-tRNA bond and release the nascent polypeptide chain.
• Non-Termination Codons:
• UUU: Encodes Phenylalanine (Phe).
• GUG: Encodes Valine (Val); acts as an alternative initiation codon in prokaryotes.

• Chronological Sequence of Discoveries:

• Path Coefficient Analysis (1921): Formulated by Sewall Wright to model causal networks, correlation, and inbreeding in quantitative genetics.
• Most Probable Producing Ability - MPPA (1937–1945): Developed by Jay L. Lush (the father of modern animal breeding) for repeated records (e.g., milk yield across lactations) based on repeatability ($r$):
  $$\text{MPPA} = \mu + \frac{n r}{1 + (n - 1)r} (\bar{P} - \mu)$$
• Henderson's Methods of Variance Component Estimation (1953): C. R. Henderson published his groundbreaking paper on Methods I, II, and III for estimating variance and covariance components in non-orthogonal, unbalanced mixed models.
• X-ray Crystallography of DNA (1953): Rosalind Franklin and Maurice Wilkins obtained Photograph 51, leading to Watson and Crick's DNA double helix model published in Nature in April 1953.
  • Correct Chronological Sequence: (A) $\to$ (C) $\to$ (B) $\to$ (D).