Inheritance

Inheritance
Gene-Simply part of your appearance. It is one unit that was inherited at conception. (Ex. The color of your hair)
Allele-an alternate form of a gene. (Ex. Red vs. non red)
Dominant vs. Recessive-Some genes are dominant and some are recessive. The dominant always cover up the recessive.
Homozygous vs. Heterozygous- Homozygous is where there are two of the same alleles. Heterozygous is two different alleles.
Genotype vs. Phenotype-Genotype is what is inside the nucleus. You can’t see what is on the inside but the phenotype is the physical appearance of a person.

Questions to think about…
When two black mice crossed together, produced black and white offspring what is the genotype of the parents? Hint: black is dominant

Answer: Heterozygous. Since there was a white mouse that means both parents had to be carriers of the white gene because white is recessive.



If bill is albino what is his genotype?

Answer: Homozygous Albino. The gene for Albino is recessive so
he had to receive that gene from both parents.

If Rex (doesn’t suffer from migraines) and Linda (who has them regularly) were to get married and have children, what is the chance of passing migraines on?

Answer: There is a 50% chance.
To determine potential offspring, it is best to do a punnett square crossing the different options for the alleles.
Example problem: Foxes, Gold coat is governed by a recessive allele g and red color by a dominant allele G. Determine the genotypic ratios from the following mating.



By looking at the punnett square, we can conclude that the genotype would be 25% homozygous dominate and 50% heterozygous and 25% homozygous recessive. 75% of the foxes would come out Red dominant and 25% would come out gold recessive.

X Linked- only appears on the X chromosome
Y Linked-only appears on the Y chromosome. Never will be in females. It is hemizygous and passed from father to all sons.
Sex Limited- the trait is on the autosomes and is only found in one gender.
Sex influenced-on the autosomes. It occurs in both genders but is dominant in one over the other