Meet Baby Blue Eyes.

We’ve seen a black child with blue eyes before.

However, this boy’s eyes are not a mutation However, this boy’s eyes are not a mutation. He inherited the trait from his parents – both of whom have brown eyes. Mom Dad

Another mystery we will tackle…

And another…

And another…

All of these questions – and many more – can be answered by studying genetics.

Genetics The scientific study of inheritance. I

In genetics, parents pass genes to their offspring.

Gene Fur color gene A segment of DNA that contains the instructions for making one specific protein. S D I P

DNA: instructions for all proteins Gene: instructions for one protein Eye color Tail length Fur color Blood type

Nucleus DNA Cell Chromosome Gene Nucleotides

Genes are passed from parent to offspring through the gametes (sex cells).

Genes are “packaged” inside gametes.

Gametes combine during the process of fertilization.

Since 2 gametes combine during fertilization, offspring receive 2copies of each gene. Egg Sperm Gene Gene Gene Offspring Gene

Trait: eye color Blue Blue Blue Blue

Trait: eye color Brown Blue Brown Blue

The three people below all have the eye color gene, but they have different alleles for that gene. Brown C G A C G T A T G Eye color gene T A G C A G T T G Blue A T C G T C A A C Eye color gene C G A G C T C T A Green G C T C G A G A T

Alleles G C T G C A T A C T A G C A G T T G C G A C G T A T G A T C G Fur color gene Fur color gene G C T G C A T A C T A G C A G T T G Black Tan C G A C G T A T G A T C G T C A A C Fur color gene C G A G C T C T A Gray G C T C G A G A T Different versions of a gene caused by different sequences of nucleotides, resulting in slightly different proteins. V G N P

Ex: for the eye color gene, brown, black, green, blue, and purple are alleles.

Do these roses have different genes, or different alleles? Both have the petal color gene They have different alleles (red, yellow)

Different genes, or different alleles?

Gene: hair color Alleles: The word “gene” is more general. The word “allele” is more specific. G S Gene: hair color Dark brown Dark red Light red Brown-black Alleles: Blonde Auburn Black

C A T G A T G G A T G U A C U A C C U A New alleles are produced by mutation. M C A T G A T G G A T G U A C U A C C U A Val Tyr His Leu

When parents with different alleles produce offspring, the offspring is known as a hybrid.

Hybrid The offspring of parents with different alleles. Curly allele Straight allele The offspring of parents with different alleles. O P A

Alleles may blend in a hybrid, or one allele may be stronger than another. BROWN HAZEL