Final answer:
Intrachromosomal recombination involves the exchange of DNA sequences between different regions of the same chromosome during meiosis. The recombination frequency measures the likelihood of this occurring between two genes, with a frequency below 50 percent indicating linked but not necessarily closely situated genes. The process leads to genetic diversity and can be exemplified by Thomas Morgan's observation of a 17 percent recombination frequency in fruit flies.
Step-by-step explanation:
Intrachromosomal Recombination
Intrachromosomal recombination is a process that occurs during meiosis in sexually reproducing organisms, where DNA sequences are exchanged between different regions of the same chromosome. This process can lead to genetic diversity by shuffling alleles, which are different versions of a gene. It involves the physical breakage and rejoining of DNA strands, which can result in the exchange of genetic material between non-sister chromatids during crossing-over. Homologous chromosomes are pairs of chromosomes that have the same structure and gene sequence, and they pair up during meiosis to facilitate genetic recombination. In terms of gene location, specific genes are located at the same locus (position) on homologous chromosomes, which allows for the correct alignment and potential for genetic recombination to occur. Regarding the recombination frequency, it quantifies the likelihood of crossing over between two genes on the same chromosome.
If two genes are close together on a chromosome, they are less likely to be separated by recombination and are considered to be linked genes. The further apart the genes are, the higher the chance that a recombination event will occur between them, thus increasing the recombination frequency. This frequency is used as a measure of the genetic distance between two genes and is often expressed in centimorgans (cM). The outcome from mitosis, by contrast, is the production of two daughter cells that are genetically identical to the parent cell. Mitosis does not involve recombination between chromosomes, as observed in meiosis.
Thomas Morgan's Observations
The recombination frequency observed by Thomas Morgan for fruit fly wing length and body color was 17 percent, demonstrating that these genes are linked but sufficiently far apart to allow for occasional recombination. A recombination frequency of below 50 percent indicates that genes are on the same chromosome and that crossing over can sometimes occur.