Genetics: The study of heredity

Heredity = the passing of traits from parents to offspring

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

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

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

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

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

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

Trait = a feature or characteristic of a person Behavior tendenciesBehavior 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 conditionsPredisposed to medical conditions –Genetics: –Environment:

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

Trait = a feature or characteristic of a person Predisposed to medical conditionsPredisposed 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 traitPhenotype = a person’s version of a trait –“physical appearance” eye color: blue hair color: black hair texture: straight

Practice List 3 traits Dash has.List 3 traits Dash has. List Dash’s phenotype for each trait.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 traitGene = part of a person’s DNA that influences a trait Eye color gene Hair color gene Face shape gene

Gene = part of a person’s DNA that controls a trait Alleles= different versions of a geneAlleles= 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.List 3 possible alleles for the hair color gene. Hair color gene

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

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

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

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = homozygous/purebredA person may inherit 2 of the same alleles = homozygous/purebred –2 dominant alleles = homozygous dominant Example: B and BExample: B and B Genotype = Phenotype = EE MomDad Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = homozygous/purebredA person may inherit 2 of the same alleles = homozygous/purebred –2 dominant alleles = homozygous dominant Example: B and BExample: B and B Genotype = BB Phenotype = EE MomDad Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = homozygous/purebredA person may inherit 2 of the same alleles = homozygous/purebred –2 dominant alleles = homozygous dominant Example: B and BExample: B and B Genotype = BB Phenotype = brown eyes EE MomDad Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = homozygous/purebredA person may inherit 2 of the same alleles = homozygous/purebred –2 recessive alleles = ee MomDad Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = homozygous/purebredA person may inherit 2 of the same alleles = homozygous/purebred –2 recessive alleles = homozygous recessive Example: b and bExample: b and b Genotype = Phenotype = ee MomDad Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = homozygous/purebredA person may inherit 2 of the same alleles = homozygous/purebred –2 recessive alleles = homozygous recessive Example: b and bExample: b and b Genotype = bb Phenotype = ee MomDad Child

Genotype = a person’s combination of alleles A person may inherit 2 of the same alleles = homozygous/purebredA person may inherit 2 of the same alleles = homozygous/purebred –2 recessive alleles = homozygous recessive Example: b and bExample: b and b Genotype = bb Phenotype = blue eyes ee MomDad Child

Alleles = different versions of a gene A person may inherit 2 different alleles =A person may inherit 2 different alleles = heterozygous/hybrid –Dominant allele masks recessive allele Example: B and bExample: B and b Genotype = Phenotype = Ee MomDad Child eE MomDad Child -or-

Alleles = different versions of a gene A person may inherit 2 different alleles =A person may inherit 2 different alleles = heterozygous/hybrid –Dominant allele masks recessive allele Example: B and bExample: B and b Genotype = Bb Phenotype = Ee MomDad Child eE MomDad Child -or-

Alleles = different versions of a gene A person may inherit 2 different alleles =A person may inherit 2 different alleles = heterozygous/hybrid –Dominant allele masks recessive allele Example: B and bExample: B and b Genotype = Bb Phenotype = brown eyes Ee MomDad Child eE MomDad Child -or-

Practice Brown hair (B) is dominant to blond hair (b).Brown hair (B) is dominant to blond hair (b). GenotypePhenotype homozygous dominant homozygous recessive heterozygous

Practice Brown hair (B) is dominant to blond hair (b).Brown hair (B) is dominant to blond hair (b). GenotypePhenotype homozygous dominant BB Brown hair homozygous recessive heterozygous

Practice Brown hair (B) is dominant to blond hair (b).Brown hair (B) is dominant to blond hair (b). GenotypePhenotype homozygous dominant BB Brown hair homozygous recessive bb Blond hair heterozygous

Practice Brown hair (B) is dominant to blond hair (b).Brown hair (B) is dominant to blond hair (b). GenotypePhenotype homozygous dominant BB Brown hair homozygous recessive bb Blond hair heterozygousBb Brown hair Which genotypes are purebred? Which is hybrid?

Practice Right-handedness (R) isRight-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).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