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Sex chromosome and autosomes difference between republicans

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Autosomes vs Sex Sex chromosome and autosomes difference between republicans During the cell division, chromatin in the nucleus shrinks to a thread like structures named chromosomes. Two major types of chromosomes can be found in eukaryotic cells.

They are autosomes and sex chromosomes. Humans have 22 homologous pairs of autosomes and one pair of sex chromosomes. What is the difference between Autosomes and Sex Chromosomes? What are Autosomes Non-sex chromosomes which determine the trait of an organism is identified as autosomes.

They are also known as somatic chromosomes since they determine the somatic characters of an individual. A genome mainly consists of autosomes. For example, human body contains 46 chromosomes within its genome and 44 chromosomes of them are autosomes. Autosomes exist as homologous pairs and 22 autosome pairs can be identified in the human genome. Both autosomal chromosomes contain the same genes, which are arranged in the same order.

But an autosomal chromosome pair differs from other autosomal chromosome pairs within the same genome. These pairs are labeled from 1 to 22, according to the base pair sizes contained in each chromosome. Autosomes also participate in sex determination. SOX9 gene is an autosomal gene on chromosome 17. It activates the function of TDF factor which is encoded by Y chromosome. TDF factor is critical in male sex determination. Hence, a mutation of SOX9 causes the development of Y chromosome, resulting in a female.

An example for aneuploidy is Dawn’s Syndrome, which possesses three copies of chromosome 21 per cell. What are Sex Chromosomes Sex chromosomes are referred to as allosomes. They determine the sex of an individual. The sex determination also happens in most animals and many plants. Humans have only 2 sex chromosomes in their genome which are labeled as X chromosome and Y chromosome.

A female individual is determined by XX and a male individual is determined by XY. During Meiosis, female gametes are made of a single X chromosome plus 22 autosomal chromosomes. Male gametes are made either of an X or Y chromosome plus 22 autosomal chromosomes. The joining of two gametes containing both X chromosomes produces a female offspring. On the contrary, the joining of two gametes, containing either an X or Y chromosomes produce a male offspring. Sex-linked genetic disorders such as hemophilia and Duchenne muscular dystrophy occur due to the defective second copy of the same gene.

Males and females contain the same copy of autosomes. They are different in males and females by their size, form, and behavior. Autosomes are labeled with numbers, from 1 to 22. Sex chromosomes are labeled with letters as XY, ZW, XO and ZO. Most of the chromosomes within a genome are autosomes. A few of the chromosomes within a genome are sex chromosomes. The 22 pairs of autosomes are homologous in humans.

Since autosomes are homomorphic, the position of the centromere is identical. Since the male sex chromosomes are heteromorphic, the position of the centromere is not identical. The position of the centromere in female sex chromosomes is identical. Autosomes contain the number of genes varying from 200 to 2000. Chromosome 1 which is the largest, carries about 2800 genes in humans. X chromosome contains more than 300 genes while Y chromosome contains only a few genes since it is small in size. Conclusion Heteromorphic sex chromosomes inherit unequal times through offspring.

Thus they do not have much implication in evolutionary processes such as mutation, selection, and genetic drift. But homomorphic chromosomes undergo evolutionary processes by homologous recombination and mutation. Thus, sex chromosomes are considered to be disproportionate in the Haldane’s rule. The genetics of sex chromosomes: evolution and implication for hybrid incompatibility.

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