Bio 004, College of the Desert
Monohybrid (Single Factor) Cross: Situation in which only one characteristic or trait is studied in the P generation and its inheritance pattern.
Hypothesis #1: There are alternate forms of heritable traits or genes.
Alleles: Alternative forms of the same traits or genes.
Example: Eye color (brown and blue).
Hypothesis #4: A sperm or egg carries only one allele for each inherited characteristic because two members of an allele pair segregate from each other during the production of gametes.
(Double Factor) : Situation in which two characteristics or traits are studied in the P generation and their inheritance pattern.
Hypothesis #1: Each pair of alleles assorts independently of the other pairs of alleles during gamete formation.
The probability of a compound event is the product of separate probabilities of the independent event.
Wild-type Traits: Those traits most often observed in nature.
2. Example: Five fingers in humans (recessive trait).
Carrier: Those with one allele for a recessive disorder, yet who do not exhibit symptoms.
2. Relatively harmless to lethal disease.
3. Follow Mendel’s laws.
4. Usually inherited from carrier parents.
5. Example: Sickle Cell Anemia in Humans.
6. Inbreeding: Mating of closely related individuals
a. Increases chances that offspring will be homozygous for a recessive disorder.
b. Example: dogs – hip dysplasia.
When the phenotype of a heterozygote is intermediate between two ozygotes (blended).Example: Pink rose
When both alleles are found in a heterozygous state and their effects are simultaneously expressed. Example: Roan cattle.
When more than two alleles for a single trait are present.Example: Blood type (A and B are both dominant while O is recessive).
One gene, many traits!
Multiple effects a single gene may have on a number of different phenotypic characteristics Example: Sickle Cell Anemia.
Additive effects of two or more genes on a single phenotypic characteristic. Example: Figure 9.22, p. 161 – A Model for Polygenic Inheritance for Skin Color.
Genes which are located close together on a chromosome and are inherited as a set.
1. Do not follow Mendel’s law of Independent assortment.
2. Example: hair color + eye color.
2. Red-green Colorblindness
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