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Albino Genetics slide presentation

 

No Genetics Calculator?  Follow the directions below!

D+SZ  X  D+SZ

Clown black X Clown black

 

First Allele Second Allele Genotype Phenotype
       
  25% SS 6.25%  DDSS Black (DD) blushing
25% DD 50% SZ 12.5%  DDSZ Black (DD) clown black
  25% ZZ 6.25%  DDZZ Black (DD) zebra
       
  25% SS 12.5%  D+SS Turquoise
50% D+ 50% SZ 25%  D+SZ Clown black
  25% ZZ 12.5%  D+ZZ Zebra lace
       
  25% SS 6.25%  ++SS Blushing
25% ++ 50% SZ 12.5%  ++SZ Silver Clown
  25% ZZ 6.25%  ++ZZ Zebra
       

This is the way I figure out crosses.  The first step is to figure how many alleles you are working with.  In this cross there are just 2.  If we added a 3rd allele like smokey there would be a third column after the zebra stripeless column.

Step 1 is to take the first allele, in this case Dark and figure out the genotypes of just that cross.  In this case there were 3 possibilities.    This is just simple 2 by 2 Punnett square.  25% DD, 50% D+, 25% ++

  D +
D DD D+
+ D+ ++

 

Leave some room between these 3 outcomes, as each one will get all of the results from the next allele SZ X SZ

  S Z
S SS SZ
Z SZ ZZ

 25% SS, 50% SZ, 25% ZZ

Each of these 3 possibilities is added to each of the 3 genotypes from the first allele.  So we end up with 9 resulting genotypes.  If this second allele had 4 possibilities you would end up with 12 total.

Total percentages are just multiplications of each one.  25% of 25% is 6.25% etc.

If there was a third allele it would be added as multiple entries after each of the second alleles.  You could end up with a maximum of 64 different genotypes from 3 alleles.  In reality I canít think of any other genes that share the same locus besides the dark and stripeless locus.  So max would be 48

Hope this helps.

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