Hemophilia sickle cell anemia thalassemia phenylketonuria class 12 Biology Ch 4 Principles of Geneti

Dear children this video is live recording of my class which includes following topics: #class12biology #biology #biologyworld #biologyclass12 #neetmotivation #neetpreparation #neetbiology #molecularbasisofinheritanceclass12 #geneticsclass12 #lacoperon #regulationofgeneexpression #education #educationalvideo #educationmatters #liveclasses #liveclassbiology #viralvideos #12biologyquestion #principlesofgenetics #geneticsclass12boards Haemophilia : A sex linked recessive disease, shows transmission from unaffected carrier female to some of the male progeny, a single protein that is a part of the cascade of proteins involved in the clotting of blood is affected, in an affected individual a simple cut results in non-stop bleeding. The heterozygous female (carrier) for haemophilia transmits the disease to sons. The possibility of a female becoming a haemophilic is extremely rare because mother of such a female is at least carrier and the father is haemophilic. The family pedigree of Queen Victoria shows a number of haemophilic descendents as she was a carrier of the disease. Sickle-cell anaemia : an autosome linked recessive trait, can be transmitted from parents to the offspring when both the partners are carrier for the gene (or heterozygous), controlled by a single pair of allele, HbA and HbS, out of the three possible genotypes only homozygous individuals for HbS (HbSHbS) show the diseased phenotype. Heterozygous (HbAHbS) individuals appear apparently unaffected but they are carrier of the disease as there is 50 per cent probability of transmission of the mutant gene to the progeny, thus exhibiting sickle-cell trait. The defect is caused by the substitution of Glutamic acid by Valine at the sixth position of the beta globin chain of the haemoglobin molecule. Phenylketonuria : the autosomal recessive trait, the affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine. As a result of this phenylalanine is accumulated and converted into phenylpyruvic acid and other derivatives. Accumulation of these in brain results in mental retardation. These are also excreted through urine because of its poor absorption by kidney. Thalassemia : an autosome-linked recessive blood disease transmitting from parents to the offspring when both the partners are unaffected carrier for the gene (or heterozygous). The defect is due to either mutation or deletion which ultimately results in reduced rate of synthesis of one of the globin chains of haemoglobin. Chromosomal Disorders - due to absence or excess or abnormal arrangement of one or more chromosomes.