Genetics

Examples in real life

Terms to know:

Passing of from one generation to the next.

Inherited forms of a characteristic.

Examples: Flower color,

Eye color, hair color, etc.

All must have at least

2 .

One from each parent.

Brown hair

Blonde hair

Blue eyes

Green eyes

Remember: 2 genes for each TRAIT

Brown hair

(brown allele)

Blonde hair

(blonde allele)

Different forms of each gene

Sometimes one gene overpowers the other.

-Gene overpowers the recessive gene

-Always shows up if present

-Gene designated by captial letter

- Ex: D

-gene that gets overpowered

-Only shows up if 2 recessive genes are present

- gene designated by lower case letter

-Ex: d

-the genes of a pair are different

-Ex: Dd

-the genes of a pair are the same

-Ex: DD or dd

The actual gene combinationEx: DD Dd dd

The physical appearance

Ex: Black Black Red

This knowledge can be used to manage or

predict physical outcomes.

Use a Punnet Square

Example:

Tongue rolling is dominant (T)

No tongue rolling is recessive (t)

Cross 2 heterozygous people: TtT

T

t

t

TT Tt

Tt tt

Genotype

# of homozygous rollers

# of heterozygous rollers

# of homozygous non rollers

1

2

1

T

T

t

t

TT

Tt

Tt

tt

Phenotype

# of rollers

# of non rollers

3

1

TT

Tt

Tt

tt

Review• Dominant overpowers Recessive • Homozygous - PP pp• Heterozygous – Pp• Genotype – the genes• Phenotype - appearance