Unit 11 Genetics Flashcards
Allele
An allele is one version of a gene. For example, the dominant and recessive versions for fur color could be White (A, dominant) and Black (a, recessive).
F1 Generation
The kids of of the P generation. If you make 1 Punnett square, the parents go on the outside and the 4 possible combinations of genes inside the squares represent the probability of each genotype of the F1 generation
F2 Generation
The children of the F1 generation
Genotype
The genes present, like homozygous dominant: AA, Heterozygous: Aa, or homozygous recessive: aa
Phenotype
The trait a person has due to their genes. Dominant traits are shown if a person has at least 1 allele for that trait (Aa or AA will show the dominant trait). Recessive traits are only expressed if the person is homozygous recessive for that trait, aa.
How are dominant traits passed down?
Dominant traits never “skip generations” because the gene for a dominant trait always results in the dominant trait showing up. For example, Aa would still look like A even though a is also present.
How are recessive traits passed down?
Recessive traits can “skip generations” because a person who has 1 recessive gene won’t show the trait. Their kids could show the trait if they get the recessive from both parents.
Widow’s peaks are a dominant trait. Can two parents with a widow’s peak have a child with no widow’s peak? Explain with a punnett square.
Yes, if the parents are both heterozygous (Aa x Aa). A: Widow’s peak, a: no widow’s peak. The offspring with the aa genotype has no widow’s peak.
The Punnett square you drew should show Aa on top, Aa on the side and the 4 inner squares are: AA, Aa, Aa, and aa
A mother who is heterozygous for an X recessive trait and an unaffected father will have a child. Does the mother have the trait, will the child? Explain.
Make a Punnett square of XaX by XY. Xa will be the recessive trait. The mother doesn’t have the trait as she is not homozygous recessive. They have a 0% chance of having a daughter with the trait (XaX or XX) and a 50% chance of a son with the trait (XaY or XY)
Dwarfism is a autosomal dominant trait. Can 2 people who are not dwarfs conceive a dwarf? Explain.
No. If a person has the trait for dwarfism, they will 100% be a dwarf. That means 2 people who are not dwarfs carry no genes for dwarfism, so they can’t have dwarf children.
Dwarfism is a autosomal dominant trait. Can 2 dwarfs have non-dwarf children? Explain.
Yes. Dwarfism is a dominant trait, so 2 dwarfs who are heterozygous for dwarfism could conceive a child who is homozygous recessive and therefor has no dwarfism.
Autosome
1 of the 44 other chromosomes besides the X and Y. These 44 chromosomes (or 22 pairs) have nothing to do with a person’s sex (male/ female)
