Mendelian Genetics Flashcards
(13 cards)
What is a dominant allele?
A dominant allele only needs one copy to express a trait.
Example: Brown eyes (B) are dominant over blue eyes (b).
What is a recessive allele?
A recessive allele needs two copies to be expressed.
Example: Blue eyes (bb).
What is a genotype?
A genotype is the genetic makeup of an organism.
Example: BB, Bb, bb.
What is a phenotype?
A phenotype is the physical trait expressed by the genotype.
Example: brown eyes, tall plant.
What is homozygous?
An organism with two identical alleles.
Example: BB or bb.
What is heterozygous?
An organism with two different alleles.
Example: Bb.
What did Mendel discover?
Traits are inherited in predictable patterns through dominant and recessive alleles.
If a heterozygous (Bb) brown-eyed parent and a homozygous (bb) blue-eyed parent have children, what are the possible eye colors?
50% brown (Bb), 50% blue (bb).
What is the phenotype ratio when two heterozygous purple-flowered pea plants (Pp) are crossed?
P = purple
p = white
75% purple, 25% white.
If a purebred tall (TT) pea plant is crossed with a short (tt) pea plant, what will the F1 generation look like?
100% tall (Tt).
What is incomplete dominance?
Neither allele is dominant –> mixture of traits
Example: Red (R) + White (W) = Pink (RW).
What is co-dominance?
Both alleles are expressed equally ie both alleles are dominant –> both traits
Plants – red + white = red flower with white spots
Animals – Cows (black cows + white cows = black with white spots or vice versa)
Example: A black-and-white spotted cow.
What would the offspring of a red snapdragon (RR) and a white snapdragon (WW) look like?
All pink (RW).
