Vocabulary:
- Trait: A characteristic that an organism can pass on to its offspring
through its genes. - Genetics: The study of heredity (how genes and traits are
passed from parents to offspring). - Gene: The set of information that controls a trait; a segment of DNA on
a chromosome that codes for a specific trait. - Dominant allele: An allele whose trait always shows up in the organism
when the allele is present. - Recessive allele: An allele that does not show up when a dominant allele
is present. - Phenotype: An organism’s physical appearance, or visible traits.
- Genotype: The alleles an organism has. For example, Bb or bb.
- Homozygous: Having two identical alleles for a trait.
- Heterozygous: Having two different alleles for a trait
- Punnett square: A chart that shows all the possible combinations of
alleles from a genetic cross.
Punnett Square example:
The homozygous blue-eyed parent can only pass down a blue allele.
The heterozygous brown-eyed parent can pass down a blue allele or a brown allele.
The children who inherit a blue allele and a brown allele, i.e., a blue-brown genotype, will have a brown-eye phenotype and have brown eyes.
Similarly, the children who inherit two blue alleles, i.e., a blue-blue genotype, will have a blue-eye phenotype and have blue eyes.
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