Genetics terms

Gene: A section of DNA that codes for traits Ex: eye color, hair color, etc… Allele: different form of the same gene Represented by capital and lowercase letters Ex: blonde hair, brown hair (B or b)

What alleles for eye color are present in your family? Tell the person sitting next to you…

Phenotype: physical appearance, expression of a gene Genotype: combination of alleles, represented by capital or lowercase letters Ex: BB, Bb, bb Phenotype: physical appearance, expression of a gene Ex: Blonde hair, brown hair, curly hair

Can people have a different genotype but the same phenotype? Explain to the person sitting across from you….

Dominant: the version of the allele that will always show if it occurs in the genotype Ex: (capital letters) BB or Bb Recessive: the version of the allele that is hidden by the dominant version if both are present Ex: (lowercase letters) bb

Is it possible for two parents that show a dominant phenotype to have a recessive child? Talk about this with your entire table…

Which of these genotypes are heterozygous? Which are homozygous? Heterozygous: Two different alleles (only the dominant version shows) Ex: Bb Homozygous: same type of alleles Ex: BB or bb Which of these genotypes are heterozygous? Which are homozygous?

If a person has a recessive phenotype is their genotype homozygous or heterozygous? Explain to your neighbor…

Monohybrid: cross, or mating, between organisms that involves only 1 pair of contrasting traits. Ex: Color (green vs yellow) Dihybrid: cross, or mating, between organisms that involves 2 pairs of contrasting traits. Ex: Color (green vs yellow) and Shape (round vs wrinkly)

In the monohybrid cross example, what % were yellow and what % were green and why? In a dihybrid cross, Why does each box have two alleles? Explain both answers to a partner.