Question

the question is based on the answer of q1 that is already solved ( i will post it )

Read the scenario then answer the question:

When Ahmad and Amina decided to get married, they were worried that their coming children might suffer from Sickle cell disease, since Amina’s mother had the disease. But the doctor made things clear ….

DOC: “Unfortunately Mr. Ahmad after tracking your family’s genetics you might be carrying the recessive allele for the disease so there is a 25% chance your children might be anemic. “

PARENTS: “ So does that mean that 25% might not even carry the disease allele?

And 50% will carry the allele but won’t have the disease? Did we mention to you that we are cousins? “

Doctor: “ Well now it makes much more sense! Children of first-cousin marriages have an increased risk of autosomal recessive genetic disorders, just like sickle cell disease, which comes from a recessive allele. Two cousins might both carry the recessive allele and transmit it both to their child which will become ill unfortunately, just like sickle cell disease.

PARENTS: “ Unfortunately, my son Seif was born with sickle cell anemia and is getting medication to carry on his life normally. My daughter Shamsa doesn’t suffer from the disease, but she might carry the recessive gene and might have anemic children in the future. “

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INFORMATION:

•You should know that S is the dominant allele for normal blood cells, and s is the recessive allele for sickle cell anemia

•Phenotypes are normal for normal trait and anemic for recessive trait

•In the pedigree we see the cross of the heterozygous parents

Brain Storming:

After knowing the history of this family, analyze, pay attention to their dialogue, and think well…. What are the genotypes of Ahmad and Amina?

Question 1:

Fill in the following Punnett Square while showing the genotypes and phenotypes of the parents and their children following the same idea of peas monohybrid cross .

Answer:

The son, Seif, is born with sickle cell anemia. This means both parents carry the allele for sickle cell anemia.

Ahmad has a heterozygous genotype as told by the doctor.

The mother can also be proved heterozygous for the trait since her mother was anemic. This means one of the affected allele was inherited from the mother.

So, the genotypes of Ahmad is Ss and that of Amina is Ss.

Gametes formed by Ahmad are S and s.

Gametes formed by Amina are S and s.

The cross can be written as Ss X Ss

..............S..............s

S..........SS............Ss

s...........Ss.............ss

1 offspring having genotype SS does not carry the affected allele and will be phenotypically normal.

2 offsprings having genotype Ss carry the affected allele but will be phenotypically normal.

1 offspring having genotype ss have both affected alleles and will be sickle cell disease.

QUESTION:

Question 2:

Fill the tables in the next two slides by doing the calculations and transforming your results into one ratio, fraction, and percentage for each genotype and phenotype

As such: ratio 1:2:1, Genotypes: BB ½ , 50%,Bb ¾  75%          Phenotype: wrinkled 75%,Smooth  25%

Ratio:    :    :
Genotypes
Number
Fraction Form
Percentage

Ratio: :        :
Phenotypes
Number
Fraction Form
Percentage

fill the tables

Answer 1

Answer-

Ques2

From the first question we know, the genotypes are SS, Ss, Ss and ss. 1/4Ss , 2/4Ss and 1/4ss.

Table:

Ratio- 1:2:1

Genotypes- SS Ss ss

Number- 3 genotypes

Fraction form- 1/4 SS 2/4 Ss 1/4 ss

Percentage(multiply each ratio by 100) - 25%SS 50%Ss 25%ss

3/4 have normal condition and 1/4 are diseased condition phenotypically.

Ratio- 3:1

Phenotypes- normal and affected with sickle cell disease.

Number- 2 phenotypes

Fraction form- 3/4 normal and 1/4 affected with sickle cell disease.

Percentage(multiply each ratio by 100)- 75% normal and 25% affected with sickle cell disease.