1. 11-2 Genetic Crosses

2. 1. Genotype and Phenotype
A. Genotype: the genetic make-up of an organism. The alleles that the organism inherits from the parents.
1.. Example – BB, Bb, bb, TT, Tt, tt
B. Phenotype: the physical appearance of an organism as a result of its genotype.

3. C. Homozygous: when both alleles of a pair are alike.
1. example – BB or bb
D. Heterozygous: when both alleles of a pair are different.
1. example – Bb
E. Probability: the likelihood that a specific event will occur.

4. Probability Punnett Squares - are used to see the probability of
different traits inherited
by the offspring

5. 2. Different Punnett Square crosses
A. Homozygous Dom – Homozygous Dom =
100% Homozygous Dominate (TT +TT)
B. Homozygous Dom.- Homozygous Rec. = 100 % Heterozygous Dominate. (TT + tt)= Tt
C. Heterozygous – Homozygous Dom. =
50 % - 50% (Tt + TT)
D. Heterozygous – Heterozygous =
25% Homo. Dom. , 50% Hetero. Dom., 25% homozygous rec. (Tt + Tt)

6. A. Involves only one pair of contrasting traits.
2. Monohybrid crosses
A. Involves only one pair of contrasting traits.

8. is crossed with a homozygous recessive individual.
E. Testcrosses: an individual with unknown genotype
is crossed with a homozygous
recessive
individual.

9. More Monohybrid Crosses

10. F. Incomplete Dominance- Occurs when two or more alleles influence the phenotype, resulting in neither factors takes on the dominant role and they compromise in a third trait.

11. Incomplete dominance

12. Complete dominance

13. H. Codominance: occurs when both alleles for a gene are expressed in a heterozygous offspring.
1. No trait is dominant and there is no blending of traits. Both traits are shown equally.

14. Blood types 1. A – AA or Ao 2. B – BB or Bo
3. AB – AB – universal recipient
4. O – oo – Universal Donor, and the recessive blood to both A blood and B blood.

15. Co-dominance – Blood types

16. Chapter 11
Section 11:3
Dihybrids

17. 3. Dihybrid Crosses A. Involves two pairs of contrasting traits

20. Constructing a Di-Hybrid cross
1. Dominant – Dominant
2. Dominant – Recessive
3. Recessive – Dominant
4. Recessive – Recessive