Biology chapter 22 Lecture No.18 Gene Linkage F.Sc. (2nd Year) скачать в хорошем качестве

Biology chapter 22 Lecture No.18 Gene Linkage F.Sc. (2nd Year)

#biology12class #biology2ndyear #chapter22 # Like Our facebook page. -----------------------------------   / bismacademy   ------------------------------------ GENE LINKAGE. Every organism possesses numerous characters controlled by thousands of genes, but the number of chromosomes is limited. .Therefore, each chromosome must carry many genes on it. Definition. All the genes located on the same chromosome are linked to each other. This phenomenon of staying together of all the genes of a chromosome is called linkage. Gene linkage is a physical relationship between genes. Gene Group. A chromosome carries its linked genes en bloc in the form of a linkage group. The number of linkage groups corresponds to the number of homologous pairs of chromosomes. Man has 23 linkage groups. Chromosomes X. Genes for colour blindness, hemophilia, gout etc. form one linkage group on human X chromosome. Chromosomes No. 11 Similarly, gene for sickle cell anemia, leukemia and albinism make another linkage group on human chromosome 11. Importance. Linked genes whose loci are close to each other do not obey Mendel‘s law of independent assortment, because these cannot assort independently during meiosis. Gene linkage also minimizes the chances of genetic recombination and variations among offspring.