Describe "crossing over" in Prophase I and how this can create genetic diversity.

Question

help?!

Answer 1

Chromosomal crossover (or crossing over) is the process by which two chromosomes pair up and exchange sections of their DNA. This often occurs during prophase 1 of meiosis in a process called synapsis. Synapsis begins before the synaptonemal complex develops, and is not completed until near the end of prophase 1. Crossover usually occurs when matching regions on matching chromosomes break and then reconnect to the other chromosome. The result of this process is an exchange of genes, called genetic recombination.  

Answer 2

The second part of your question was not answered following the explanation of crossing-over.

Genes carried on the same chromosome are said to be linked and usually are inherited together.  That fact would limit the genetic variation.  For example, a gene for high protein production is linked to tall height.  There exists a gene for low protein production and short height on the homologous chromosome.  Occasionally when crossing over occurs, new gene combinations occur that may give an advantage to the offspring.  Thus a new combination of short height and high protein can be created as well as an offspring with tall height and low protein.  The farther apart two different genes are on the chromosome the greater the probability of crossing-over which increases the number of new gene combinations.  Multiple segments can be crossed over scrambling the gene sequence in an organism.