Ba pr Ge Describe or explain homologous recombination between human X and Y chro
ID: 198665 • Letter: B
Question
Ba pr Ge Describe or explain homologous recombination between human X and Y chromosome yo dat you (mR cell desc ident Describe or provide explanation of the human Barr body. Include in your answer the number of Barr bodies present in a XXX individual, the frequency of XXX individuals in the human population, comment or discussion of XXX individuals phenotype, and comment or discussion on why trisomy of X is allows a normal phenotype while by comparison trisomy of most autosomes is lethal? How many base pairs of DNA represent the haploid human genome? How many base pairs of DNA represent the haploid chimpanzee genome? Assume the similarity between human and chimpanzee genomes is 97.5%. Based on 97.5% similarity how many base pairs do the chimpanzee and human genomes differ by?Explanation / Answer
1:Homologous recombination is a type of genetic recombination in which the DNA exchanged between the identical chromosomes. Autosomes exchange their genetic material during this homologous recombination in meosis. X Y chromosomes due to its dissimilarity will not form homologous pair entairly. But some regions of X and Y chromosomes acts similar to autosomes and exchange their genetic material. This regions are identified as pseudoautosmal regions or simply PAR. There are two pseudoautosomal regions called PAR1 and PAR 2. PAR 1 located at terminal possition in the short arms of chromosomes while PAR 2 located at the terminal long arm of the chromosomes. There are 24 genes identified in PAR 1 region and 4 genes in PAR 2. Deletion of PAR 1 may leads to loss of recombimation and male infertility.
2. The barr body is an inactive X chromosome in vegatative cells. Among two X chromosomes present in normal female one is randomly inactivated during embryogenesis. The number of barr bodies in normal female is one. In XXX female there will be two barr bodies. This syndrome occurs one in 1000 births. No physical abnormalities would be resulted due to XXX syndrome and female able to have normal sexual devolopment. They usually taller than normal individuals with an increased risk of learning disabilities and delayed development of speech and language skills and also associated with delayed development of motor skills and weak muscle tone etc. As additional X chromosomes will be in activated they will not be associated with sexual abnormalities unlike other trysomic conditions.
3. The sperm and egg cells have haploid genome. The haploid genome nearly have three billion base pairs. If 97.5% similarity exsists between human and chimpanzee than the similar base pairs would acconut for 292.5*109 nearly.
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