Genetics Problems

A man is heterozygous for curly hair. What is his genotype? Cc

His wife is homozyg. dominant for curly hair. What is her genotype? CC

What are the chances they will have a child with curly hair? Cc x CC 100% or 4 out of 4

Albinos have almost no pigment in their skin, hair and eyes.

A man is albino. What is his genotype? aa

His wife is heterozygous. What is her genotype? Aa

Do the square for their children. aa x Aa

What are the chances a child will be normal? ½ Aa

What are the chances a child will be normal? ½ Aa

Being able to roll your tongue is a dominant trait.

Two parents are heterozygous. Do the square.

What are the chances their child CAN roll his tongue?

What are the chances their child CAN roll his tongue? TT can roll tongue. Tt can roll tongue. So ¾ chance CAN roll tongue.

A “widow’s peak” means your hairline is not straight across. Straight line 

A man with a “widow’s peak” is Ww. His wife is WW. Do the square.

What is the genotype and phenotype ratios of his children? What does the box say about genotypes? What does the box say about phenotypes? That Means…

The GENOTYPE ratios are … ½ WW and ½ Ww (or 50% WW and 50% Ww)

The PHENOTYPE ratios are … 4/4 widow’s peak (or 100% widow’s peak)

Notice that the genotype and phenotype ratios don’t have to be the same!!

Review For these problems there are always only 2 phenotypes (curly/straight, freckles/no freckles, etc.) Use capitals and lower cases but only ONE letter per trait

Review MM means You can make the protein mm means You cannot make the protein because you did not get the recipe to make it.

Review If someone has freckles, can you tell if they are FF or Ff? If so, how? FF and Ff look EXACTLY the same.