Exploring dominant and recessive traits

1. Exploring Dominant and Exploring Dominant and
Recessive TraitsRecessive Traits
BiologyBiology
CRHS NeistadtCRHS Neistadt
Courtesy of Miss SmithCourtesy of Miss Smith

2. Questions to Think AboutQuestions to Think About

Let’s list together any genetic traits Let’s list together any genetic traits
you can think of on the whiteboard.you can think of on the whiteboard.
•For example: eye color, hair colorFor example: eye color, hair color

Where do traits come from?Where do traits come from?

What do you think Dominant or What do you think Dominant or
Recessive Traits are?Recessive Traits are?

3. Where do traits come from?Where do traits come from?

Your parents pass them down Your parents pass them down
through genetic traits.through genetic traits.

You receive half of your genes from You receive half of your genes from
each parenteach parent

Each person has about 70,000 pairs Each person has about 70,000 pairs
of genes.of genes.

Genes can be dominant or recessiveGenes can be dominant or recessive

4. Dominant Traits vs. Dominant Traits vs.
Recessive TraitsRecessive Traits

Dominant trait-Strongest traitDominant trait-Strongest trait

Dominant trait-Masks or covers up Dominant trait-Masks or covers up
the weaker traitthe weaker trait
•Which hair color do you think is Which hair color do you think is
dominant?dominant?
•Which eye color do you think is Which eye color do you think is
dominant?dominant?
•Which hair color do you think is Which hair color do you think is
recessive?recessive?

5. Formal DefinitionFormal Definition

Dominant TraitDominant Trait: the trait observed n : the trait observed n
the first generation when parents the first generation when parents
that have different traits are bred.that have different traits are bred.

Recessive TraitRecessive Trait: a trait that : a trait that
reappears in the second generation reappears in the second generation
after disappearing in the first after disappearing in the first
generation when parents with generation when parents with
different traits are bred.different traits are bred.

6. Common MisconceptionCommon Misconception

Recessive Traits are not rare traits.Recessive Traits are not rare traits.

Dominant or recessive traits may be Dominant or recessive traits may be
more common in a population.more common in a population.

Example: Blonde hair is very Example: Blonde hair is very
common in parts of Scandinavia.common in parts of Scandinavia.

Example: The trait of having six Example: The trait of having six
fingers on one hand is a dominant fingers on one hand is a dominant
trait!trait!

7. Partner Time!Partner Time!

Get with a partner.Get with a partner.

Complete the worksheet together having Complete the worksheet together having
your partner help you identify if you have your partner help you identify if you have
the traits listed.the traits listed.

Put a check mark beside the trait you Put a check mark beside the trait you
have.have.

We will share our results together at the We will share our results together at the
end!end!

When you have completed the worksheet, When you have completed the worksheet,
glue this page into your notebook. It glue this page into your notebook. It
should go onto page 13.should go onto page 13.

8. EarlobeEarlobe

9. DimplesDimples

10. Tongue RollerTongue Roller

11. FrecklesFreckles

12. EyelashesEyelashes

13. Hair LineHair Line

14. Hair TypeHair Type

15. Hair ColorHair Color

16. EyesEyes

17. LipsLips

18. ThumbThumb

19. Skin PigmentSkin Pigment

20. VisionVision

21. Tongue to NoseTongue to Nose

22. FingersFingers

Do you have hair on your knuckles?Do you have hair on your knuckles?

23. Interlaced FingersInterlaced Fingers

Without thinking about it, interlace Without thinking about it, interlace
your fingers like the picture shows.your fingers like the picture shows.

If your left thumb is over your If your left thumb is over your
right, then you have the dominant right, then you have the dominant
trait.trait.

24. PinkiePinkie

25. Questions to think aboutQuestions to think about

Were traits that are dominant, Were traits that are dominant,
actually dominant among our actually dominant among our
classmates?classmates?

Is it possible to have traits that are Is it possible to have traits that are
not visible in your parents?not visible in your parents?

26. If time permits:If time permits:

Glencoe Biology Text chapter 10Glencoe Biology Text chapter 10

Worksheet Worksheet #49 & #17 from
Pacemaker Text: Chapter 5