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Valued Member
Educator
13 years ago
star thanks for providing that website, i took a look and I made a summary

Table. Simple Mathematical Rules Useful in Working Genetics Problems

Crosses between Organisms Heterozygous for Genes Exhibiting Independent Assortment

Number of Heterozygous Gene pairs Number of Different Types of Gametes Formed Number of Different Genotypes Produced Number of Different Phenotypes Produced

n   2n    3n     2n*

1   2      3       2
2   4      9       4
3   8      27     8
4   16    81     16

*The fourth column assumes that dominance and recessiveness are operational for all gene pairs.
wrote...
Valued Member
Educator
13 years ago
I also looked further into that website and found some more insight:

Independent Assortment Leads to Extensive Genetic Variation

We have seen that for any individual, the number of possible gametes, each with different chromosome compositions, is 2n, where n equals the haploid number. Thus, if a species has a haploid number of 4, then 24 or 16 different gamete combinations can be formed as a result of independent assortment. Although this number is not high, consider the human species, where n = 23. If we calculate 223, we find more than 8 x 106, or more than 8 million, different types of gametes are possible. Because fertilization represents an event involving only one of approximately 8 x 106 possible gametes from each of two parents, each offspring represents only one of (8 x 106)2 or 64 x 1012 potential genetic combinations. This number of combinations of chromosomes is far greater than the number of humans who have ever lived on Earth! It is no wonder that, except for identical twins, each member of the human species demonstrates such a distinctive appearance and individuality. Genetic variation resulting from independent assortment has been extremely important to the process of evolution in all organisms.
wrote...
13 years ago
thanks star and bioman!  I appreciate all your help. 
You're right, he's not going to ask about the penta cross.
wrote...
Valued Member
Educator
13 years ago
You're welcome Wink Face

On a side note, I highly recommend you read this article Duddy published earlier today.

I highlighted the important sections; should explain what we couldn't explain Face with Stuck-out Tongue

[See Attachment]

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wrote...
13 years ago
star thanks for providing that website, i took a look and I made a summary

Table. Simple Mathematical Rules Useful in Working Genetics Problems

Crosses between Organisms Heterozygous for Genes Exhibiting Independent Assortment

Number of Heterozygous Gene pairs Number of Different Types of Gametes Formed Number of Different Genotypes Produced Number of Different Phenotypes Produced

n   2n    3n     2n*

1   2      3       2
2   4      9       4
3   8      27     8
4   16    81     16

*The fourth column assumes that dominance and recessiveness are operational for all gene pairs.


this actually solved a lot of the problems i was having in genetics... thx Slight Smile
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