9 Difference Between Autosomes And Sex Chromosomes

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Many animals, including humans have two types of chromosomes: Autosomes and sex chromosomes. Sex chromosomes are those that are needed for determining sex (male or female) of an individual. Autosomes are all the rest of the chromosomes that are not needed for sex determination.

What Is Autosome?

Autosomes are chromosomes that do not carry any genes that determine the sex of the individual. Autosomes are referred to numerically e.g chromosome 1, chromosome 2 according to a traditional sort order based on size, shape and other properties.  Autosomes differ from sex chromosomes, which make up the 23rd pair of chromosomes in all normal human cells and come in two forms, called X and Y. Autosomes control the inheritance of an organism’s characteristics except the sex-linked ones, which are controlled by the sex chromosomes.

Humans have a total of 46 chromosomes in each body cell; 44 of these are Autosomes. You get one set of 22 autosomes from your mother and another 22 from your father. It is often easier to think about our Autosomes in pairs because even though we have 44 autosomes.

What You Need To Know About Autosomes

  1. Autosomes are chromosomes that do not carry any genes that determine the sex of the individual.
  2. There is one pair of sex chromosomes (X&Y) in mammals.
  3. Males and females contain the same copy of Autosomes.
  4. Autosomes are labeled with numbers from 1 to 22.
  5. Given that Autosomes are homomorphic , the centromere position is identical.
  6. Autosomes contain the number of genes varying from 200 to 2000. Chromosome 1 which is the largest carries about 2800 genes in humans.
  7. The 22 pairs of Autosomes are homologous in humans.
  8. Most of the chromosomes within a genotype are Autosomes.
  9. Autosomal linked disorders show Mendelian inheritance.

What Are Sex Chromosomes?

A sex chromosome is a type of chromosome that participates in sex determination. Humans and most other mammals have two sex chromosomes, the X and Y. females have two X chromosomes in their cells whereas males have both X and Y chromosome. The X chromosome resembles a large autosomal chromosome with a long and short arm. The Y chromosome has one long arm and a very short second arm. All egg cells contain an X chromosome while sperm contain an X or Y chromosome.

During meiosis the male XY sex-chromosome pair separates and passes on an X or a Y to separate gametes; the result is that one-half of the gametes (sperm) that are formed contains the X chromosome and the other half contains the Y chromosome. The female has two X chromosomes and all female egg cells normally carry a single X. The eggs fertilized by X-bearing sperm become females (XX) whereas those fertilized by Y-bearing sperm becomes males (XY). This arrangement means that it is the male that determines the sex of the offspring when fertilization occurs.

What You Need To Know About Sex Chromosomes

  1. Sex chromosomes carry sex-determining genes (but may also carry many other genes that have nothing to do with sex).
  2. All other chromosomes (22 pairs in humans) are Autosomes.
  3. They are different in males and females by their size, form and behavior.
  4. Sex chromosomes are labeled with letters as XY, ZW, XO and ZO.
  5. Given that 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.
  6. X chromosomes contains more than 300 genes while Y chromosomes contains only a few genes since it is small in size.
  7. Female sex chromosomes (XX) are homologous (homomorphic) while male sex chromosomes (XY) are non-homologous (heteromorphic).
  8. A few of the chromosomes within a genotype are sex chromosomes.
  9. Sex linked disorders show Non-Mendelian inheritance.

Difference Between Autosomes And Sex Chromosomes In Tabular Form

BASIS OF COMPARISON AUTOSOMES SEX CHROMOSOMES
Description Autosomes are chromosomes that do not carry any genes that determine the sex of the individual.   Sex chromosomes carry sex-determining genes (but may also carry many other genes that have nothing to do with sex).  
Number There is one pair of sex chromosomes (X&Y) in mammals.   All other chromosomes (22 pairs in humans) are Autosomes.  
Similarity Males and females contain the same copy of Autosomes.   They are different in males and females by their size, form and behavior.  
Labeling Autosomes are labeled with numbers from 1 to 22.   Sex chromosomes are labeled with letters as XY, ZW, XO and ZO.  
Position Of Centromere Given that Autosomes are homomorphic , the centromere position is identical.   Given that 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.  
Number Of Genes Autosomes contain the number of genes varying from 200 to 2000. Chromosome 1 which is the largest carries about 2800 genes in humans.   X chromosomes contains more than 300 genes while Y chromosomes contains only a few genes since it is small in size.  
Nature The 22 pairs of Autosomes are homologous in humans.   Female sex chromosomes (XX) are homologous (homomorphic) while male sex chromosomes (XY) are non-homologous (heteromorphic).  
Majority Chromosomes Most of the chromosomes within a genotype are Autosomes.   A few of the chromosomes within a genotype are sex chromosomes.  
Mendelian Inheritance Autosomal linked disorders show Mendelian inheritance.   Sex linked disorders show Non-Mendelian inheritance.  

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