Bell Ringer A child is born with blue eyes even though BOTH his parents have brown eyes. How is this possible? Can two blue eyed parents have a brown eyed child? Explain why or why not.

Genetics: The study of heredity

Heredity = the passing of traits from parents to offspring

Heredity = the passing of traits from parents to offspring Trait = A feature or characteristic of a person Physical appearance Behavior tendencies Predisposed to medical conditions A person’s traits are influenced by: their genetic inheritance environmental factors What is a trait?

Trait = a feature or characteristic of a person Physical appearance Genetics: Environment: hair color eye color face shape hair texture smile shape

Trait = a feature or characteristic of a person Physical appearance Genetics: genes determine natural hair color Environment: hair color eye color face shape hair texture smile shape

Trait = a feature or characteristic of a person Physical appearance Genetics: genes determine natural hair color Environment: sun or hair dyes change hair color hair color eye color face shape hair texture smile shape

Trait = a feature or characteristic of a person Behavior tendencies Genetics: Environment:

Trait = a feature or characteristic of a person Behavior tendencies Genetics: genes determine the tendency to use a certain hand Environment:

Trait = a feature or characteristic of a person Behavior tendencies Genetics: genes determine the tendency to use a certain hand Environment: can learn to use the opposite hand

Trait = a feature or characteristic of a person Predisposed to medical conditions Genetics: Environment:

Trait = a feature or characteristic of a person Predisposed to medical conditions Genetics: genes determine a risk of heart disease Environment:

Trait = a feature or characteristic of a person Predisposed to medical conditions Genetics: genes determine a risk of heart disease Environment: eating healthy foods and exercising can reduce risk

Trait = a feature or characteristic of a person Phenotype = a person’s version of a trait “physical appearance” hair color: black eye color: blue hair texture: straight

Practice List 3 traits Dash has. List Dash’s phenotype for each trait.

Trait = a feature or characteristic of a person Gene = part of a person’s DNA that influences a trait Eye color gene Face shape gene Hair color gene

Gene = part of a person’s DNA that controls a trait Alleles= different versions of a gene Eye color gene: brown allele Eye color gene: blue allele

Practice List 3 possible alleles for the hair color gene.

Alleles = different versions of a gene Dominant Allele Represented by a capital letter Example: B for brown eyes Recessive allele Represented by a lowercase letter Example: b for blue eyes

Alleles = different versions of a gene All people have 2 alleles for every gene (one from each parent) Allele of eye color gene from dad Allele of eye color gene from mom

Alleles = different versions of a gene All people have 2 alleles for every gene (one from each parent) Genotype = a person’s combination of alleles “genetic makeup” Allele of eye color gene from dad Allele of eye color gene from mom

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = purebred 2 dominant alleles = purebred dominant Example: B and B Genotype = Phenotype = Mom Dad E E Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = purebred 2 dominant alleles = purebred dominant Example: B and B Genotype = BB Phenotype = Mom Dad E E Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = purebred 2 dominant alleles = purebred dominant Example: B and B Genotype = BB Phenotype = brown eyes Mom Dad E E Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = purebred 2 recessive alleles = Mom Dad e e Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = purebred 2 recessive alleles = purebred recessive Example: b and b Genotype = Phenotype = Mom Dad e e Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = purebred 2 recessive alleles = purebred recessive Example: b and b Genotype = bb Phenotype = Mom Dad e e Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = purebred 2 recessive alleles = purebred recessive Example: b and b Genotype = bb Phenotype = blue eyes Mom Dad e e Child

Alleles = different versions of a gene A person may inherit 2 different alleles = hybrid Dominant allele masks recessive allele Example: B and b Genotype = Phenotype = Mom Dad Mom Dad e E E e -or- Child Child

Alleles = different versions of a gene A person may inherit 2 different alleles = hybrid Dominant allele masks recessive allele Example: B and b Genotype = Bb Phenotype = Mom Dad Mom Dad e E E e -or- Child Child

Alleles = different versions of a gene A person may inherit 2 different alleles = hybrid Dominant allele masks recessive allele Example: B and b Genotype = Bb Phenotype = brown eyes Mom Dad Mom Dad e E E e -or- Child Child

Practice Brown hair (B) is dominant to blond hair (b). Genotype Phenotype purebred dominant purebred recessive hybrid

Practice Brown hair (B) is dominant to blond hair (b). Genotype Phenotype purebred dominant BB Brown hair purebred recessive hybrid

Practice Brown hair (B) is dominant to blonde hair (b). Genotype Phenotype purebred dominant BB Brown hair purebred recessive bb Blond hair hybrid

Practice Brown hair (B) is dominant to blond hair (b). Genotype Phenotype purebred dominant BB Brown hair purebred recessive bb Blond hair hybrid Bb Which genotypes are purebred? Which is hybrid?

Practice Right-handedness (R) is dominant to left-handedness (r). What genotype(s) could a right-handed person have? What genotype(s) could a left-handed person have? RR or Rr rr

Practice In pea plants, green peas (G) are dominant to yellow peas (g). What would be the genotype of a: -purebred green pea? -hybrid green pea? -yellow pea? GG Gg gg