Genetics

Mr. SkirbstLife Science

Topic 08

Genetics

Geneticsthe study of heredity

Geneticsthe study of heredity

Heredity is the passing of traits to offspring

Geneticsthe study of heredity

Heredity is the passing of traits to offspring

Traits are characteristics of an organism (ex. Hair color, eye color, skin color, etc.)

GENES- units of heredity

GENES- units of heredity

Dominant – stronger trait “T”

GENES- units of heredity

Dominant – stronger trait “T”Recessive – weaker trait “t”

GeneticsZygote – fertilized egg

GeneticsZygote – fertilized egg

Homozygous (purebred) –Contains all one trait(ex. TT or tt)

GeneticsZygote – fertilized egg

Heterozygous (hybrid) –Contains mixed traits(ex. Tt)

GeneticsPhenotype – physical appearance(ex. Hair color)

GeneticsPhenotype – physical appearance(ex. Hair color)Genotype –Genetic makeup(ex. Tt or TT)

Probability

Probability - the possibility (or likelihood)

that an event will happen(ex. flipping a coin, lottery, rain,

characteristics of offspring)

ProbabilityPunnett Square:

ProbabilityPunnett Square: - used to show possible gene

combinations in a cross between two organisms

(shows genetic probability)

ProbabilityPunnett Square: bb

B

BCross between:*Purebred recessive &*Purebred dominant

ProbabilityPunnett Square: bb

B

B B

B

B

B

b b

b b

Cross between:*Purebred recessive &*Purebred dominantProduces:*Offspring that are allhybrids

ProbabilityPunnett Square: bB

b

B

Cross between:*Hybrid & Hybrid

ProbabilityPunnett Square: bB

b

B

Cross between:*Hybrid & HybridProduces:*Offspring possibilities 2 hybrids, 1 purebred dominant, and1 purebred recessive

B

b

B

B

B

b

b

b

Punnett Square

1. Cross a homozygous dominant witha heterozygous organism

2. Cross a heterozygous organism with ahomozygous recessive

3. Cross a homozygous recessive with ahomozygous dominant

4. Cross a homozygous recessive with ahomozygous recessive

Punnett Square (examples)

Genetic SurveyTrait Male Female Total

Hair (Black) _____ _____ _____(Brown) _____ _____ _____(Blonde) _____ _____ _____(Red) _____ _____ _____

Eyes (brown) _____ _____ _____(hazel) _____ _____ _____(blue) _____ _____ _____

Tongue(roller) _____ _____ _____(non-roller) _____ _____ _____

Ear lobe(attached)_____ _____ _____(not attached)____ _____ _____