Question

How does crossing-over increase variation in genes?

Answer 1

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAA&url=https%3A%2F%2Fanswers.yahoo.com%2Fquestion%2Findex%3Fqid%3D20071112204555AAJw6Ul&ei=bSUnVcq5JY24ogTf1IGIDw&usg=AFQjCNGUJPuFLbZLXZeykCrPVaIyFzSNaw&sig2=ZOPZLIflMZAQbOdtjVj5zQ

Answer 2

In prophase 1 crossing over causes chromosome segments to exchange and leads to new combinations of genes

Answer 3

You have one set of chromosomes from your mother, and one set from your father.

You can think of it like this:

Your mother gave you these chromosomes: {M1, M2, M3, . . . M22, M23}, and your father gave you these: {F1, F2, F3, . . ., F22, F23}.

When you produce sperm or eggs (depending on your sex), you give just one "1" chromosome, one "2" chromosome, one "3" chromosome, etc. You don't give BOTH of them to your sperm/egg.

If there was no crossing over, then there would only be 2^26 possible combinations. These different combinations help give rise to genetic variability. This is a pretty big number, but your body is even smarter thank you think, and realized that with crossing over, you can get WAY more genetic variability.

Imagine that M1 and F1 are each a stack of cards, and each card is a genetic trait. In crossing over, you're pretty much shuffling the cards, so in the end you get two new chromosomes that are distinct from the original ones. Eventually, you will pass along just one of these.

If all the chromosomes cross over, you get almost an infinite number of possible combinations.