genetics the study of the inheritance of traits

inheritance the passing of traits from parents to offspring

Gametes male gamete: sperm female gamete: egg

Gametes sperm egg

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

Tall plants Short plants Axial flowers Terminal flowers Inflated pods Constricted pods Green pods Yellow pods Yellow peas Green peas Round peas Wrinkled peas

Mendel’s Experiments tall plants and short plants axial flowers and terminal flowers inflated pods and constricted pods yellow pods and green pods

Mendel’s Experiments yellow peas and green peas round peas and wrinkled peas green seed coats and white seed coats

purebred an organism that has had the same traits for many generations

1. Pollen-containing structures are removed from short-plant flowers. 2. Tall-plant pollen is collected using a brush. 3. Tall-plant pollen is placed onto stigmas of short-plant flowers.

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

Mendel’s Experiments tall + short = tall ???

F1—1st Filial Generation Mendel’s Experiments F1—1st Filial Generation

Mendel’s Experiments F2 Generation

Mendel’s Experiments tall + tall = tall

Mendel’s Experiments tall + short = tall

hybrid an offspring of two genetically unrelated individuals

Mendel’s Experiments Each offspring had two factors for each trait, one from each parent.

Mendel’s Experiments Each factor in the set of two factors for a trait was either dominant or recessive.

Mendel’s Experiments F2 Generation

x

TT x tt Tt (F1)

Tt x Tt TT Tt Tt tt

Terms phenotype genotype — tall — TT, Tt

What Do You Think? What was the phenotype of the peas in Mendel’s F1 generation? tall

What Do You Think? List the genotypes of the peas in the F1 generation. Tt

tall and short What Do You Think? What phenotypes did Mendel see in the F2 generation? tall and short

TT, Tt, tt What Do You Think? What genotypes did Mendel find in the F2 generation? TT, Tt, tt

chromosome number the number of chromosomes in the nucleus

Punnett square a diagram used to visualize genetic crosses

parent characteristic

parent characteristic offspring offspring offspring offspring

Hybrid Tall Parent Tt x tt T t t Purebred Short Parent t

Hybrid Tall Parent Tt x Tt T t T Hybrid Tall Parent t

Purebred Short Parent tt x tt t t t Purebred Short Parent t

Purebred Tall Parent TT x tt T T t Tt Tt Purebred Short Parent t Tt Tt

Hybrid Tall Parent Tt x Tt T t T TT Tt Hybrid Tall Parent t Tt tt

TT tt 25% TT 25% Tt Tt Tt 25% Tt 25% tt

incomplete dominance both genes influence the characteristic of an organism a type of inheritance in which the genes expressing a particular characteristic are neither dominant nor recessive;

Hybrid CwCr x CwCr Cw Cr Cw CwCw CwCr Hybrid Cr CwCr CrCr

codominance a type of inheritance pattern where two traits are equally expressed

HBHB x HWHW Chestnut HB HB HW HBHW HBHW White HW HBHW HBHW

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

X chromosome the female sex chromosome

Y chromosome the male sex chromosome

XX x XY X X X XX XX Y XY XY

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

XgY x XGXG Xg Y XG XG

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

XgY x XGXG Xg Y XG XGXg XGY XG XGXg XGY

XGY x XGXg XG Y XG XGXG XGY Xg XGXg XgY