How Can Homologous Chromosomes Be Identified?
Chromosomes condense and become visible during cell division. Normal cell division, mitosis, duplicates the DNA and then divides it accurately into two so that the new new cells formed are genetically identical. If you can take a cell at the stage in mitosis where the chromosomes have just condensed, but have not yet duplicated, it is possible to photograph the individual chromosomes with a powerful microscope-linked camera. Homologous chromosomes are the same size and have the same pattern of banding and it is possible to sort the individual chromosome images so that the homologous chromosomes are paired up. There are some obvious variations between different human chromosomes – the pair of chromosomes that a labelled as chromosome 1 are long, about twice as long as chromosome 8, and about 10 times as long as the short stubby chromosome 21. Most good biology A level text books will have a picture showing homologous chromosomes from a human cell. A good one is Collins Advanced Science,
Related Questions
- What are theses alternate forms of a gene called? Genes located on a homologous chromosomes may have alternate forms that control different forms of a trait?
- Is the gene present on one of the homologous chromosomes transcribed or both the homologous chromosomes?
- How many chromatids are involved in crossing-over of a homologous pair of chromosomes?
