Genetic Vocabulary
Allele – one form of a gene (1 trait). Ex. Hair Color
Dominant – Allele (trait) that shows physically in the offspring. Dominant Alleles are represented with a capital
letter. Ex. A = Black Hair
Recessive – Allele (Trait) that does NOT show physically in the offspring. Recessive Alleles are represented
with a lower case letter. a = Blonde Hair
DNA – Information passed on through cell reproduction. DNA makes up genes. EX.
Gene – Carries the information about heredity in the sperm (male) and egg (female). Ex.
Chromosomes – Genes strung together to make a ladder chain.
Genotype – refers to the gene that is used for a particular trait. Ex. AA, Aa, aa
Phenotype – refers to the trait or characteristic that is used in a particular gene. Ex. Black hair, Brown hair or
Blonde Hair.
Heredity – passing down of mental and physical traits (characteristics) from parents to their children. Ex.
Grandchild has grandpa’s dimples.
Heterozygote – Offspring that has two different alleles for a given trait. This is also known as a HYBRID. Ex. Aa
Homozygote – Offspring that has two identical alleles for a given trait. Dominate is known as PRUEBREED,
Recessive is known as RARE. Ex. AA or aa
Offspring – Descendants that are born from sexual reproduction in a certain line of genetics. Ex. Kitties,
puppies, babies, & other animals.
Sexual Reproduction – Sperm and Egg create a genetically unique offspring from two parents.
Asexual Reproduction – One parent creates a genetically identical offspring from itself.
Gregor Mendel – Monk scientist that discovered passing of DNA in sexual reproduction.
Genetic Predictions
1. In daisies, the yellow petal is dominant over the white. If a homozygous dominant (AA) and
heterozygous (Aa) daisy crossed pollenated…
A
A
_____ How many would be homozygous dominant?
A
_____ How many would be heterozygous?
_____ How many would be white?
AA
AA
Aa
Aa
a
_____ How many would be yellow?
2. Curly hair is dominant over straight hair. Cross a male who is heterozygous (Aa) for curly hair with a
female who is homozygous recessive (aa) for straight hair.
_____ How many offspring would be homozygous recessive?
_____ How many would be heterozygous?
_____ How many would have curly hair?
_____ How many would have straight hair?
3. In frogs, dark green spots are dominant over yellow. What would be the results of two hybrid (Aa)
parents?
_____ How many of the offspring would be homozygous dominant?
_____ How many would be heterozygous?
_____ How many would have green spots?
_____ How many would have yellow spots?
4. Horned cattle are dominant to hornless cattle. Use a Punnett Square to show the expected offspring
form the mating of a heterozygous horned bull (Aa) with a homozygous recessive (aa) hornless cow.
_____ Horned?
_____ Hornless?
_____ Homozygous dominant?
_____ Heterozygous?
_____ Homozygous recessive?
__________ Possible Genotypes?
__________ Possible Phenotypes?
5. Sickle Cell Anemia is a recessive trait. In families where both parents have the heterozygous sickle cell
trait, how many of the offspring would you expect?
_____ Normal?
_____Sickle Cell Anemia?
_____ Homozygous dominant?
__________ Possible Genotypes?
_____ Carrier?
_____ Homozygous recessive?
__________ Possible Phenotypes?