Title 05. PRINCIPLES OF INHERITANCE AND VARIATION.pdf ✅

Tendeney of genes in a chromosome to remain together & pass as such to next generation. Result of Crossing over. LINKAGE RECOMBINATION Exchange of genes or chromosomal parts to break already existing linkages & formation of new linkages. CROSSING-OVER CYSTIC FIBROSIS Autosomal recessive chronic lung infection SICKLE CELL ANEMIA Autosomal recessive shape of RBCs changes (Sickle Shaped) COLOR BLINDNESS x – linked recessive disorder defect in red/ green cone of eye HAEMOPHILIS x – linked recessive disorder THALASSEMIA Autosomal recessive formation of abnormal hemoglobin PHENYLKETONURIA Autosomal recessive Accumulation of phenyl alanine TURNER'S SYNDROME Absence of x chromosomes 45 chromosomes (44+ xo) KLINEFETTER'S SYNDROME presence of additional copy of x chromosome 47 chromosomes (44+xxy) DOWN'S SYNDROME Trisomy of 21st chromosome LAW OF DOMINANCE LAW OF SEGREGATION LAW OF INDEPENDENT ASSORTMENT • Characters are controlled by discrete unit called factors. • Factors occur in pair. • In dissimilar pair one dominated over other • During the gamete formation the factors segregate from each other. • Homozygous produces similar gametes while heterozygous produce dissimilar • When two pairs of traits are combined in a hybrid segregation of one pair of character is independent of the other pair of characters. 7 CONTRASTING CHARACTERS (1) Plant height:- Tall/ Dwarf (2) Flower color :- Purple/ white, (3) Flower position:- Axial/ Terminal, (4) Seed colour:- Yellow/ Green (5) Seed shape:- Round/ Wrinkled, (6) Pod colour:- Green/ Yellow, (7) Pod Shape:- Inflated/Constricted BACK CROSS TEST CROSS Cross hybrid and any one of the parents Cross hybrid and recessive parent. GENE GENETIC DISORDER CHROMOSOMAL CHROMOSOMAL THEORY OF INHERITANCE BY SUTTON AND BOVERY, 1902 • Behaviour of chromosome is parallel to genes behavior. • Both occur in pairs in diploid cells. SEX DETERMINATION sex chromosomes also called allosomes, INCOMPLETE DOMINANCE The heterozygous offspring shows intermediate characters. Eg – Mirabilis jalapa MULTIPLE ALLELISM A gene existing in more than two allelic forms. Eg:- A B O blood group CO – DOMINANCE Two alleles of a gene are equally dominant. Eg:- A B O blood group PLEIOTROPY Ability of gene to have multiple phenotypic effects as it influences number of characters simultaneously. NON - MENDELIAN INHERITANCE FRAME SHIFT POINT Deletion or addition of base in a DNA segment, Change in single base pair of DNA PRINCIPLES OF INHERITANCE AND VARIATION MUTATION Additional set of chromosomes is present. Addition or deletion of one or more chromosome, A segment of chromosome is removed and joined In reverse order. segment of chromosome is transferred to non- homologous chromosome, Deleted chromosome segment gets embedded to its normal homologous chromosome. A segment of chromosome gets lost. EUPLOIDY ANEUPLOIDY INERSION TRANSLOCATION DUPLICATION DELETION CHROMOSOMAL MENDELIAN Phenotypic ratio: 9:3:3:1 Genotypic ratio: 1:2:1:2:4:2:1:2:1 Clotting of blood is affected Phenotypic ratio - 3:1 Genotypic ratio - 1:2:1 ( FATHER OF GENETICS ) GREGOR MENDEL