Autosomes vs Chromosomes
As cell theory suggested, a new cell begins from a pre-existing cell by the cell division. Further studies have recognized the importance of the cell division and function of the chromosome. Chromosomes can be seen in nucleus, in eukaryotes whereas, in prokaryotes, it is in the cytoplasm.
Chromosomes are observed clearly only in nuclear division. Between the periods of nuclear divisions called interphase, arms of chromosomes are not clear, hence appears like a bundle of strings called chromatin.
Two types of chromosomes can be seen in a cell; autosomes and sex determining chromosomes. In a female, sex determining pair of chromosome is XX and males have XY chromosomes. Y chromosome is shorter than the X chromosome and lacks some gens that occur in X chromosome.
Chromosomes are made up of two identical DNA strands. DNA is a polymer of nucleotides, which is composed of sugar, phosphate and ester phosphate bonds. These two DNA strands are attached with each other from one location called centromere, and these two strands are defined as sister chromatids. Centromere can be anywhere along the length of the chromosome, and two DNA strands are covered with histone protein.
Eukaryotes have linear DNA forming chromosomes in nucleus, carrying information from generation to generation, whereas prokaryotes have circular DNA in the cytoplasm, which carries genetic information. It is not covered with protein to form chromosome; therefore, called naked DNA. These chromosomes are responsible for the transmission of the genetic information from generation to generation. The unit of the inheritance (i.e. genes), which is a small part of DNA, are arranged along the chromosome. In one chromosome, there may be several thousand of genes, which are responsible for different characteristics (Taylor et al, 1998).
Each species has a unique number of chromosomes in each cell. Humans have 46 chromosomes, fruit flies have 8 chromosomes, cats have 38, and dogs have 78 (Taylor et al, 1998). In a cell, chromosomes exist as pairs. These chromosome pairs are identical and, therefore, called homologous chromosomes. So, a human has 23 homologous chromosomes. From the 23 chromosomes, 22 are autosomes and one pair is sex chromosomes.
Autosomes are chromosomes in human which determines general characteristics in both female and male. In a human, 22 pairs of chromosomes are autosomes, and the other pair determines the gender of the human. Females have two X chromosomes, whereas males have one Y chromosome and one X chromosome.
Autosomes are numbered according to their size. A whole set of chromosome arranged and shown in a microphotograph is called karyogram.
What is the difference between Chromosome and Autosome?
• The major difference between the chromosome and autosome is that, every autosome is a chromosome, whereas all chromosomes are not autosomes. There are other sex chromosomes too.
• Mainly autosomes determine the other characteristics except the sex determination, whereas some of the chromosomes determine the gender.
• Number of chromosome is higher in a cell than the number of autosomes in a cell.
• Autosomes have homologous pairs, whereas some chromosomes have different pair: in a male, sex is determined by the XY.
Taylor, D.J., Green N.P.O., Stout, G.W., (1998), Biological Science. Cambridge University Press, Cambridge