Transcript Sex-Linked Traits

Monohybrid Crosses:
Inheritance of single genes
Features to question
look for
General
format:
• Example:
Genotype of individual 1
Genotype of individual 2
• Mendel crosses a heterozygous tall pea
plant with a short pea plant. If tall is
dominant to short, what is the genotype
& phenotype ratio of the F1 generation?
Explains dominance
What you’re looking for
Solution
1. Use a let statement to show which traits are
dominant and recessive.
 Let T = tall, t = short
Use the first letter of the dominant
trait! Capital = dominant,
lowercase = recessive
2. Determine the genotypes of the parents.
Individual 1: heterozygous tall: Tt
Individual 2: short: tt
Means 2 different alleles!
Recessive in this case, so it
must be 2 lowercase letters
3. Draw a Punnett Square, as you learned in the handout
and fill it in
T
t
t
Tt
tt
t
Tt
tt
4. Answer the question:
Phenotype ratio is 2 Tall : 2 short
Genotype ratio is 2 Tt : 2 tt
Remember: it means
letters/alleles
Remember: it means
physical appearance