1. Traits & Dominance
ISN p. 31

2. 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.

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

4. Define TRAIT
A feature or characteristic about an organism

5. 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??

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

7. 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

8. 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

9. 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

10. 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)

11. 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

12. 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!)