com/watch?v=JKXAdwCib…(Maybe skip the first minute and a half.)That might include genes for both traits, one alone or neither, but crossing over is frequent in meiosis, so genes do get mixed up.......
Edit: Just to be clear, crossing over involves long chunks of DNA moving from one matching chromosome to the other. You can see cartoon versions on Youtube e.g.
http://www.youtube.com/watch?v=JKXAdwCib…
(Maybe skip the first minute and a half.)
That might include genes for both traits, one alone or neither, but crossing over is frequent in meiosis, so genes do get mixed up.
The x chromosome of john is either of his maternal grandmother or grandfather. becos John's mother genotype is xx(one of John's maternal grandmother and another of his grandfather) and after gametogenesis there will be 2 possibilities x(from his maternal grandma) and x(from his maternal grandpa) one of which would have combined with y of his father.
crossing over can just alter certain points or genes between 2 similar chromosome, but cannot mix the 2 chromosomes. So it can affect the baldness of a person (which depends upon particular genes), but it doesn't mean that the chromosomes are mixed.
