geneticsgeneticsthe study of the inheritance of traitsthe study of the inheritance of traits

inheritanceinheritancethe passing of traits from parents to offspringthe passing of traits from parents to offspring

• male gamete: sperm

• female gamete: egg

• male gamete: sperm

• female gamete: egg

GametesGametes

GametesGametesspermsperm eggegg

haploidhaploida cell that has one of each kind of chromosome that is normally found in the organism

a cell that has one of each kind of chromosome that is normally found in the organism

Tall plantsTall plants Short plantsShort plants

Axial flowersAxial flowers Terminal flowersTerminal flowers

Inflated podsInflated pods Constricted podsConstricted pods

Mendel’s Experiments

Mendel’s Experiments

• tall plants and short plants

• axial flowers and terminal flowers

• inflated pods and constricted pods

• yellow pods and green pods

• tall plants and short plants

• axial flowers and terminal flowers

• inflated pods and constricted pods

• yellow pods and green pods

• yellow peas and green peas

• round peas and wrinkled peas

• green seed coats and white seed coats

• yellow peas and green peas

• round peas and wrinkled peas

• green seed coats and white seed coats

Mendel’s Experiments

Mendel’s Experiments

purebredpurebredan organism that has had the same traits for many generations

an organism that has had the same traits for many generations

1. Pollen-containing structures are removed from short-plant flowers.

1. Pollen-containing structures are removed from short-plant flowers.2. Tall-plant pollen

is collected using a brush.

2. Tall-plant pollen is collected using a brush.

3. Tall-plant pollen is placed onto stigmas of short-plant flowers.

3. Tall-plant pollen is placed onto stigmas of short-plant flowers.

crosscrossmating purebred plants of opposite traits to test how they inherit traits

mating purebred plants of opposite traits to test how they inherit traits

Mendel’s Experiments

Mendel’s Experiments

shortshorttalltall ++ talltall??????==

Mendel’s Experiments

Mendel’s Experiments

F1—1st Filial GenerationF1—1st Filial Generation

Mendel’s Experiments

Mendel’s Experiments

F2 GenerationF2 Generation

Mendel’s Experiments

Mendel’s Experiments

talltalltalltall ++ talltall==

shortshorttalltall ++ talltall==

Mendel’s Experiments

Mendel’s Experiments

hybridhybridan offspring of two genetically unrelated individuals an offspring of two genetically unrelated individuals

• Each offspring had two factors for each trait, one from each parent.

• Each offspring had two factors for each trait, one from each parent.

Mendel’s Experiments

Mendel’s Experiments

• Each factor in the set of two factors for a trait was either dominant or recessive.

• Each factor in the set of two factors for a trait was either dominant or recessive.

Mendel’s Experiments

Mendel’s Experiments

Mendel’s Experiments

Mendel’s Experiments

F2 GenerationF2 Generation

xx

ttttTTTT xx Tt (F1)Tt (F1)

TtTt xx TTTTTtTt TtTt TtTt tttt

TermsTerms• phenotype• genotype

• phenotype• genotype

— tall — tall

— TT, Tt— TT, Tt

What was the phenotype of the peas in Mendel’s F1 generation?

What was the phenotype of the peas in Mendel’s F1 generation?

What Do You Think?What Do You Think?

talltall

List the genotypes of the peas in the F1 generation.List the genotypes of the peas in the F1 generation.

TtTt

What Do You Think?What Do You Think?

What phenotypes did Mendel see in the F2 generation?What phenotypes did Mendel see in the F2 generation?

tall and shorttall and short

What Do You Think?What Do You Think?

What genotypes did Mendel find in the F2 generation?What genotypes did Mendel find in the F2 generation?

TT, Tt, ttTT, Tt, tt

What Do You Think?What Do You Think?

chromosome numberchromosome numberthe number of chromosomes in the nucleusthe number of chromosomes in the nucleus

Punnett squarePunnett squarea diagram used to visualize genetic crossesa diagram used to visualize genetic crosses

parent characteristicparent characteristic

pare

nt c

hara

cter

istic

pare

nt c

hara

cter

istic

offspringoffspring offspringoffspring

offspringoffspringoffspringoffspring

parent characteristicparent characteristic

pare

nt c

hara

cter

istic

pare

nt c

hara

cter

istic

Hybrid Tall Parent

Hybrid Tall Parent

Purebred Short

Parent

Purebred Short

Parent

Tt x ttTt x ttTT tt

tt

tt

Hybrid Tall

Parent

Hybrid Tall

Parent

TT ttTT

tt

Hybrid Tall Parent

Hybrid Tall ParentTt x TtTt x Tt

Purebred Short Parent

Purebred Short Parenttt x tttt x tttt tt

tt

tt

Purebred Short

Parent

Purebred Short

Parent

Purebred Tall ParentPurebred

Tall ParentTT x ttTT x ttTT TT

tt

tt

TtTt TtTt

TtTt TtTt

Purebred Short

Parent

Purebred Short

Parent

Tt x TtTt x TtTT tt

TT

tt

TTTT TtTt

TtTt tttt

Hybrid Tall Parent

Hybrid Tall Parent

Hybrid Tall

Parent

Hybrid Tall

Parent

ttttTtTtTtTtTTTTTT

25%

Tt25%

Tt25%

tt25%

incomplete dominanceincomplete dominancea type of inheritance in which the genes expressing a particular characteristic are neither dominant nor recessive;

a type of inheritance in which the genes expressing a particular characteristic are neither dominant nor recessive;

both genes influence the characteristic of an organismboth genes influence the characteristic of an organism

Hybrid Hybrid

HybridHybrid

CwCr x CwCrCwCr x CwCrCwCw CrCr

CwCw

CrCr

CwCwCwCw CwCrCwCr

CwCrCwCr CrCrCrCr

codominancecodominancea type of inheritance pattern where two traits are equally expressed

a type of inheritance pattern where two traits are equally expressed

ChestnutChestnut

WhiteWhite

HBHB x HWHWHBHB x HWHW

HBHB

HBHWHBHW HBHWHBHW

HBHWHBHW HBHWHBHW

HBHB

HWHW

HWHW

multiple gene inheritancemultiple gene inheritancetwo or more gene pairs are responsible for producing a single trait

two or more gene pairs are responsible for producing a single trait

X chromosomeX chromosomethe female sex chromosomethe female sex chromosome

Y chromosomeY chromosomethe male sex chromosomethe male sex chromosome

XX x XYXX x XYXX

XXXX XXXX

XYXY XYXY

XX

XX

YY

sex-linked traitsex-linked traita characteristic that has a gene on the X-chromosome but no gene on the Y-chromosome

a characteristic that has a gene on the X-chromosome but no gene on the Y-chromosome

XgY x XGXGXgY x XGXG

XgXg YY

XGXG

XGXG

carriercarrieran individual who possesses a gene for a specific trait but does not exhibit that trait

an individual who possesses a gene for a specific trait but does not exhibit that trait

XgXg

XGXgXGXg XGYXGY

XGXgXGXg XGYXGY

YY

XGXG

XGXG

XgY x XGXGXgY x XGXG

XGY x XGXgXGY x XGXg

XGXG

XGXGXGXG XGYXGY

XGXgXGXg XgYXgY

YY

XGXG

XgXg