Crossing Over
Crossing over is the interchange of chromosomal parts between non-sister chromatids of a homologous pair of chromosomes resulting in recombination of genes
Crossing over was discovered by Morgan
Crossing over is the interchange of chromosomal segments between the homologous chromosomes
It occurs during meiosis or gametogenesis
The crossing over occur only between non-sister chromatids of the homologous chromosomes
The number of crossing over depends upon the length of the chromosome. The longer the length, the higher the percentage of crossing over
When the genes are located distantly the change for crossing over is higher. When the genes are closely located the change for crossing over is lesser
The number of crossing over between two genes is represented by percentage of crossing over
The percentage of crossing over is directly proportional to the distance between two genes
The percentage of crossing over is the expression of the number of recombinaations in percentage to the total number of offspring
Percentage of total number of
The percentage of crossing over is also called frequency of crossing over
Thus percentage of crossing over = Frequency of crossing over =Percentage of recombination
Generally crossing over is less frequent neat the centromere and the tip of the4 chromosome
Crossing over at one point prevents another crossing over nearby
When there is a single crossing over in a homologous chromosome, it is called single crossing over
When there are two cross over in a homologous chromosome, it is called double crossing over
When there are many cross over in a homologous chromosome, it is called multiple crossing over
The crossing over may be formed between two strands or 3 stands or 4 strands. It is always formed between non-sister chromatids
