Generation 1: Meet Maria and Carlos Rodriguez. Neither Maria nor

Question

Carlos exhibits the genetic mutation, but both carry one copy of the
recessive gene (R). For this mutation, let's use "r" for the recessive
allele and "R" for the dominant allele. Both Maria and Carlos have
the genotype "Rr".
Generation 2: Maria and Carlos have three children: Juan, Elena,
and Sofia. Each child inherits one allele from each parent:
• Juan: Rr (Carrier, but does not show the mutation)
• Elena: RR (Neither carrier nor affected)
• Sofia: rr (Shows the genetic mutation)
Generation 3: Sofia marries David, who does not carry the
recessive gene (RR). Together, they have four children: Miguel,
Lucia, Roberto, and Ana.
• Miguel: Rr (Carrier, but does not show the mutation)
• Lucia: Rr (Carrier, but does not show the mutation)
• Roberto: Rr (Carrier, but does not show the mutation)
• Ana: Rr (Carrier, but does not show the mutation)
Generation 4: Miguel marries Laura, who also does not carry the
recessive gene (RR). They have two children: Carlos Jr. and Isabella.
• Carlos Jr.: RR (Neither carrier nor affected)
• Isabella: Rr (Carrier, but does not show the mutation)
Now! Create your own Punnett Squares

Answer 1

To illustrate the inheritance of the recessive genetic mutation using Punnett squares, we'll create squares for each generation based on the provided genotypes.

Generation 1: Maria (Rr) x Carlos (Rr)

Punnett Square:

\[ \begin{array}{c|c|c} & R & r \ \hline R & RR & Rr \ \hline r & Rr & rr \ \end{array} \]

Results:

• 1 RR (Elena)
• 2 Rr (Juan and either Juan or Sofia)
• 1 rr (Sofia)

Generation 2: Sofia (rr) x David (RR)

Punnett Square:

\[ \begin{array}{c|c|c} & R & R \ \hline r & Rr & Rr \ \hline r & Rr & Rr \ \end{array} \]

Results:

• 100% Rr (Miguel, Lucia, Roberto, Ana; all carriers but do not show the mutation)

Generation 3: Miguel (Rr) x Laura (RR)

Punnett Square:

\[ \begin{array}{c|c|c} & R & R \ \hline R & RR & RR \ \hline r & Rr & Rr \ \end{array} \]

Results:

• 2 RR (Carlos Jr.)
• 2 Rr (Isabella; she is a carrier but does not show the mutation)

Summary of Generations:

• Generation 1:
  • Children are 1 RR (Elena), 2 Rr (Juan), and 1 rr (Sofia).
• Generation 2:
  • Children of Sofia (rr) and David (RR) are all Rr (Miguel, Lucia, Roberto, Ana).
• Generation 3:
  • Children of Miguel (Rr) and Laura (RR) yield Carlos Jr. (RR) and Isabella (Rr).

This sequence of Punnett squares shows how the recessive mutation can be passed down through generations, even if it does not exhibit itself in all descendants.