Exploring Dominant and Exploring Dominant and Recessive TraitsRecessive Traits

BiologyBiology

CRHS NeistadtCRHS Neistadt

Courtesy of Miss SmithCourtesy of Miss Smith

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?

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

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?

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.

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!

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.

EarlobeEarlobe

DimplesDimples

Tongue RollerTongue Roller

FrecklesFreckles

EyelashesEyelashes

Hair LineHair Line

Hair TypeHair Type

Hair ColorHair Color

EyesEyes

LipsLips

ThumbThumb

Skin PigmentSkin Pigment

VisionVision

Tongue to NoseTongue to Nose

FingersFingers

Do you have hair on your knuckles?Do you have hair on your knuckles?

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 right, If your left thumb is over your right, then you have the dominant trait.then you have the dominant trait.

PinkiePinkie

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?

If time permits:If time permits:

Glencoe Biology Text chapter 10Glencoe Biology Text chapter 10 Worksheet Worksheet #49 & #17 from

Pacemaker Text: Chapter 5