Mitosis

1
Key Terms

• ________________
• the physical expression of a trait (tall, short)

• ________________
• The phenotype is determined by the combination of
  alleles found in the genotype (TT, Tt, tt)

2
(No Transcript)
3

• ________________
• The dominant trait will be expressed when the
  dominant allele is paired with the recessive
  allele in a hybrid. A Tt plant will have a
  phenotype of tall.
• Capital letters represent the dominant allele.

• _________________
• The recessive trait is the one that is not
  expressed when the dominant allele is present in
  the genotype.
• Lower case letters represent the recessive allele

4
Tt x Tt T t
T TT Tt
t Tt tt

• _________________
• Refers to a genotype in which the alleles are
  different (Tt)

Tt x Tt T t
T TT Tt
t Tt tt

• _________________
• Describes a genotype where the alleles are the
  same (TT, tt)

5
____________________

• Members of a pair of alleles for a given trait
  are segregated (separated) when gametes are
  formed.
• If a parent plant has the genotype Tt, then it
  will produce two types of gametes, T and t. Each
  gamete contains only one of the alleles for plant
  height.

T
Tt
Gamete
t
Parent
Gamete
6
___________________________________

• When two or more pairs of characteristics are
  considered at one time, each pair shows dominance
  and segregation independently of the other.
• If a parent plant has the genotype TtRr, then it
  will produce four different types of gamte
  combinations in equal numbers,
• ¼ TR, ¼ Tr, ¼ tR, ¼ tr

TR
TtRr
Tr
tR
Parent
tr
7
________________________ Tt x Tt
When two heterozygous F1 plants are crossed.

• 31 Phenotype ratio
• 3 Tall, 1 Short
• 121 genotype ratio
• TT, Tt, Tt, tt

Tt x Tt T t
T TT Tt
t Tt tt
8
1. What are purebred pea plants? 2. How
did Mendel ensure that he had a purebred pea
plant?
PRACTICE QUESTIONS!
9
PRACTICE QUESTIONS!
3. What is a monohybrid cross? 4. What
phenotypic and genotypic ratios result from such
a cross?
10
PRACTICE QUESTIONS!
5. In humans, the ability to taste
phenylthiocarbamide (PTC), T, is dominant to
non-tasting, t. Determine the expected genotypic
and phenotypic ratios resulting from a cross
between a heterozygous taster and a non-taster.