Traits & Dominance ISN p. 31

What is GENETICS? What is HEREDITY? The study of how traits are inherited through the interactions of genes. What is HEREDITY? The passing of traits from parent to offspring.

Review: What is an ALLELE? The different forms of a trait that a gene may have

Define TRAIT A feature or characteristic about an organism

Inherited Traits Traits that you inherit from your mom and dad – they are in your DNA. Eye color Hair color Height Can you think of others??

Acquired Traits Traits that you have to learn from your environment Riding a bike Reading Writing Can you think of others??

Describe DOMINANT A trait that covers over, or dominates, another form of that trait Trait that always shows up, even when only one of the two alleles is in the dominant form Shown by a capital letter Ex: Brown hair, B

Describe RECESSIVE A trait that is covered up, or dominated, by another form of that trait and seems to disappear. Hidden when the other copy of the gene contains the dominant allele. A recessive allele shows up only when there is no dominant allele present Shown with a lower-case letter Ex: Blonde hair, b

CODOMINANCE When two dominant alleles occur together, they make something half-way in between the two traits. Ex: In flowers, red is dominant (R), white is also dominant (W) When they appear together, RW = pink flowers

What is HOMOZYGOUS? Both alleles are the same When offspring inherit two dominant genes, (one dominant gene from each parent) they are said to be homozygous dominant (BB) When offspring inherit two recessive genes, (one recessive gene from each parent) they are said to be homozygous recessive (bb)

What is HETEROZYGOUS? When offspring inherit one dominant gene and one recessive gene, they are said to be heterozygous Since the dominant gene will always be expressed, they are said to be heterozygous dominant When offspring are heterozygous, they are said to be a CARRIER of the recessive trait Hair color Bb, dominant allele is brown hair Person is a carrier for blonde hair

In your ISN p. 30 Make a T-chart and list 10 of your acquired traits and 15 inherited traits. Be specific! Summary: (5 sentence minimum) Describe the difference between dominant and recessive genes. Of your inherited traits, which ones do you THINK are dominant and which are recessive? (It’s ok to guess!)