Intro to Genetics

Key Terms Trait – A physical characteristic encoded by a gene Ex: Eye color, hair color, freckles Allele – One possible version of one specific gene Represented by letters Ex: F = freckles f = no freckles

Key Terms Dominant – Type of allele that may mask the effect of others Represented by capital letters Ex: B for brown eyes Recessive – Type of allele that may be masked by others Represented by lowercase letters Ex: b for blue eyes

Key Terms Homozygous – Two alleles of the same type are present Ex: BB bb Heterozygous – Two different alleles are present Ex: Bb

Key Terms Phenotype – Physical appearance of trait Described with words: Purple flower, white flower Genotype – Genetic makeup (alleles) Represented by letters: PP, Pp, pp Represented by words: Homozygous dominant, homozygous recessive, heterozygous pp Pp PP

Examples of Genotypes gg GG Gg For a parrot with feathers, green feathers are dominant (G) and blue feathers are recessive (g). What genotype is a homozygous recessive parrot? What genotype is a homozygous dominant parrot? What genotype is a heterozygous parrot? gg GG Gg

Green is dominant to blue Monohybrid Crosses Punnett Square – method used to predict outcomes of simple genetic crosses Monohybrid cross – genetic cross for a single trait G g G g GG Gg Gg Gg Gg gg Green is dominant to blue

Red hair (R) is dominant over blond hair (r) Red hair (R) is dominant over blond hair (r). Make a cross between a heterozygous red head and a blond. R r r Rr rr What percentage of the offspring will have red hair? 50%

T t Tt tt t In pea plants, tall pea plants (T) are dominant Let’s try some more… In pea plants, tall pea plants (T) are dominant over short pea plants (t). Construct a Punnett Square for a heterozygous tall pea plant and a short pea plant. T t What are the percentage of phenotypes? Tt tt t 50% tall 50% short

Heterozygous Homozygous Flashcards For each key term, write the definition and draw a picture to help you remember. Get them checked off by me for a grade! Genotype Phenotype Allele Trait Dominant Recessive Heterozygous Homozygous

Trait Brochures Pretend you are writing a pamphlet explaining the difference between the following terms: Genotype Phenotype Allele Trait Dominant Recessive Heterozygous Homozygous Use any three sets of terms, please include definitions and pictures! If you want to do a comic, set of memes, or anything else, please let me know. 

Non-Mendelian Genetics

Complete Dominance One allele completely masks the other Use uppercase and lowercase versions of the same letter

Incomplete Dominance rr ww rw Neither allele is dominant Heterozygotes show a blended phenotype Use different, lowercase letters rr ww rw

Codominance BB WW BW Both alleles are dominant Heterozygotes show a mixed or patterned phenotype (both alleles show equally) Use different, uppercase letters BB WW BW