ICAR AIEEA PG 2024 - Plant Biotechnology

Parental genotypes:
Dwarf, red snapdragon: $ttRR$ (produces gametes with alleles $tR$)
Homozygous tall, white snapdragon: $TTrr$ (produces gametes with alleles $Tr$)
Crossing $ttRR \times TTrr$ produces 100% $F_1$ individuals with the genotype $TtRr$.
Phenotypic expression:
For plant height: Allele $T$ is completely dominant over $t$, so $Tt$ plants are Tall.
For flower color: Alleles $R$ and $r$ exhibit incomplete dominance, resulting in a blended intermediate Pink phenotype in the heterozygous ($Rr$) state.

Meiosis is a specialized type of cell division that reduces the chromosome number by half, creating four genetically diverse haploid daughter cells from a single diploid germ cell. In sexually reproducing eukaryotes, meiosis is the essential cellular process that produces haploid gametes (sperm and egg cells in animals, or microspores and megaspores that form gametophytes in plants).

Prions (proteinaceous infectious particles), discovered and defined by Stanley B. Prusiner in 1982 (Nobel Prize 1997), are unique infectious agents composed entirely of misfolded protein, devoid of any nucleic acid (neither DNA nor RNA). They cause transmissible spongiform encephalopathies (TSEs) such as scrapie in sheep, bovine spongiform encephalopathy (BSE / mad cow disease) in cattle, and Creutzfeldt-Jakob disease (CJD) in humans by inducing the normal cellular prion protein ($PrP^C$) to refold into the abnormal, insoluble, beta-sheet-rich pathogenic isoform ($PrP^{Sc}$).