Bell Ringer 1)A child is born with blue eyes even though BOTH his parents have brown eyes. How is this possible? 2)Can two blue eyed parents have a brown

Bell RingerBell Ringer

1)1) A child is born with blue eyes even A child is born with blue eyes even though BOTH his parents have though BOTH his parents have brown eyes. How is this possible?brown eyes. How is this possible?

2)2) Can two blue eyed parents have a Can two blue eyed parents have a brown eyed child? Explain why or brown eyed child? Explain why or why not.why not.

Genetics:Genetics:The study of The study of heredityheredity

HeredityHeredity = = the passing of the passing of traits traits

from from parentsparents to to offspringoffspring

Heredity Heredity = = the passing of the passing of traits traits

from parents to from parents to offspringoffspring Trait Trait = A feature or characteristic = A feature or characteristic

of a personof a person Physical appearancePhysical appearance Behavior tendenciesBehavior tendencies Predisposed to medical conditionsPredisposed to medical conditions

A person’s traits are influenced by:A person’s traits are influenced by: their genetic inheritance their genetic inheritance environmental factorsenvironmental factors

What is a trait?

TraitTrait = a feature or = a feature or characteristic of characteristic of a a personperson

Physical Physical appearanceappearance Genetics: Genetics:

Environment:Environment:

eye eye colorcolor

hair hair colorcolor

smile smile shapeshape

hair hair texturetexture

face face shapeshape


Physical Physical appearanceappearance Genetics:Genetics: genes genes

determine determine natural hair natural hair colorcolor

Environment:Environment:eye eye colorcolor






Physical Physical appearanceappearance GeneticsGenetics:: genes genes

determine determine natural natural hair colorhair color

EnvironmentEnvironment:: sun or hair sun or hair dyesdyes change hair change hair colorcolor

eye eye colorcolor






BehaviorBehavior tendencies tendencies Genetics:Genetics:



BehaviorBehavior tendencies tendencies Genetics:Genetics: genes determine the genes determine the

tendency to use a certain handtendency to use a certain hand Environment:Environment:


BehaviorBehavior tendencies tendencies Genetics:Genetics: genes determine the genes determine the

tendency to use a certain handtendency to use a certain hand Environment:Environment:

can can learn to use learn to use

the opposite the opposite

handhand


PredisposedPredisposed to medical conditions to medical conditions Genetics:Genetics:



PredisposedPredisposed to medical conditions to medical conditions Genetics:Genetics: genes determine a genes determine a risk of risk of

heart diseaseheart disease Environment:Environment:


PredisposedPredisposed to medical conditions to medical conditions Genetics:Genetics: genes determine a genes determine a risk of risk of

heart diseaseheart disease Environment:Environment: eating eating

healthy foods and healthy foods and

exercising can reduce exercising can reduce

risk risk


PhPhenotypeenotype = a person’s = a person’s versionversion of a traitof a trait ““phphysicalysical appearance” appearance”

eye color: eye color: blueblue

hair color: hair color: blackblack

hair texture: hair texture: straightstraight

PracticePractice

List 3 traits Dash has.List 3 traits Dash has.

List Dash’s phenotype for each trait.List Dash’s phenotype for each trait.


GeneGene = part of a person’s = part of a person’s DNA DNA that that influencesinfluences a trait a trait

Eye color geneEye color gene

Hair color geneHair color gene

Face shape geneFace shape gene

GeneGene = = part of a person’s part of a person’s DNA DNA that controls a that controls a traittrait

AllelesAlleles= different = different versionsversions of a of a genegene

Eye color Eye color gene: gene: brownbrown alleleallele

Eye color Eye color gene: gene: blueblue alleleallele

PracticePractice

List 3 possible alleles for the hair color List 3 possible alleles for the hair color gene.gene.

Hair color geneHair color gene

AllelesAlleles = different = different versions of a versions of a

gene gene Dominant AlleleDominant Allele

Represented by a Represented by a capitalcapital letter letter ExampleExample: : BB for for brownbrown eyes eyes

Recessive alleleRecessive allele Represented by a Represented by a lowercaselowercase letter letter

Example:Example: bb for for blueblue eyes eyes


gene gene All people have All people have 2 alleles2 alleles for every for every

gene (one from each gene (one from each parentparent))

Allele of Allele of eye color eye color gene gene from from mommom

Allele of Allele of eye color eye color gene gene from dadfrom dad


gene gene All people have 2 alleles for every All people have 2 alleles for every

gene (one from each parent)gene (one from each parent)

GenGenotypeotype = a person’s = a person’s

combinationcombination of alleles of alleles ““gengenetic etic makeup”makeup” Allele of Allele of

eye color eye color gene gene from from mommom

Allele of Allele of eye color eye color gene gene from dadfrom dad

GenotypeGenotype = a person’s = a person’s combination of combination of

allelesalleles A person may inherit 2 of the A person may inherit 2 of the samesame

alleles = alleles = purebredpurebred

2 dominant alleles = 2 dominant alleles = purebred purebred dominantdominant ExampleExample: B and B: B and B

Genotype =Genotype =

Phenotype =Phenotype =EE EE

MomMom DadDad

ChildChild




2 dominant alleles = 2 dominant alleles = purebredpurebred dominantdominant ExampleExample: B and B: B and B

Genotype = Genotype = BBBB

Phenotype =Phenotype =EE EE

MomMom DadDad

ChildChild




2 dominant alleles = 2 dominant alleles = purebred purebred dominantdominant ExampleExample: B and B: B and B

Genotype = Genotype = BBBB

Phenotype = Phenotype = brown eyesbrown eyesEE EE

MomMom DadDad

ChildChild

GenotypeGenotype = = a person’s a person’s combination of combination of



2 recessive alleles =2 recessive alleles =

ee ee

MomMom DadDad

ChildChild




2 recessive alleles = 2 recessive alleles = purebred purebred recessiverecessive ExampleExample: b and b: b and b

Genotype = Genotype =

Phenotype =Phenotype = ee ee

MomMom DadDad

ChildChild





Genotype = Genotype = bbbb

Phenotype =Phenotype = ee ee

MomMom DadDad

ChildChild





Genotype = Genotype = bbbb

Phenotype = Phenotype = blue eyesblue eyes ee ee

MomMom DadDad

ChildChild


gene gene A person may inherit 2 A person may inherit 2 differentdifferent

alleles = alleles =

hybridhybrid Dominant allele Dominant allele masks masks recessive allelerecessive allele

ExampleExample: B and b: B and b

Genotype = Genotype = Phenotype = Phenotype =

EE ee

MomMom DadDad

ChildChild

ee EE

MomMom DadDad

ChildChild-or--or-



alleles = alleles =



Genotype = Genotype = BbBb Phenotype = Phenotype =

EE ee

MomMom DadDad

ChildChild

ee EE

MomMom DadDad

ChildChild-or--or-



alleles = alleles =



Genotype = Genotype = BbBb Phenotype = Phenotype = brown eyesbrown eyes

EE ee

MomMom DadDad

ChildChild

ee EE

MomMom DadDad

ChildChild-or--or-

PracticePractice

Brown hair (B) is dominant to blond hair (b).Brown hair (B) is dominant to blond hair (b).

GenotypeGenotype PhenotypePhenotype

purebred purebred dominantdominant

purebred purebred recessiverecessive

hybridhybrid

PracticePractice



purebred purebred dominantdominant BBBB Brown hairBrown hair

purebred purebred recessiverecessive

hybridhybrid

PracticePractice

Brown hair (B) is dominant to blonde hair (b).Brown hair (B) is dominant to blonde hair (b).



purebred purebred recessiverecessive bbbb Blond hairBlond hair

hybridhybrid

PracticePractice




purebred purebred recessiverecessive bbbb Blond hairBlond hair

hybridhybrid BbBb Brown hairBrown hair

Which genotypes are Which genotypes are purebredpurebred? Which ? Which isis hybridhybrid??

PracticePractice

Right-handedness (R) is Right-handedness (R) is

dominant to left-handedness (r). dominant to left-handedness (r).

What genotype(s) could a What genotype(s) could a right-handedright-handed person have?person have?

What genotype(s) could a What genotype(s) could a left-handed left-handed person have?person have?

RR or RrRR or Rr

rrrr

PracticePractice

In pea plants, green peas (G) are In pea plants, green peas (G) are dominant to yellow peas (g).dominant to yellow peas (g).

What would be the genotype of a:What would be the genotype of a:

-purebred green pea?-purebred green pea?

-hybrid green pea?-hybrid green pea?

-yellow pea?-yellow pea?

GGGG

GgGggggg

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Bell Ringer 1)A child is born with blue eyes even though BOTH his parents have brown eyes. How is this possible? 2)Can two blue eyed parents have a brown