Traits

TraitsCam-Tu Diep

Traits• Look at the people around you. No other person looks

or acts just like you. The ways in which people differ are called traits.

Our difference

s are called traits.

People have many different traits•Hair color•Skin color•Eye color•Height•Freckles•Earlobes•Nose shape

•Traits help us tell people apart. Traits are differences between people.

Red hair is a trait.

So are blue eyes.

We also share many of the same traits

•We walk with twos legs•We sing and speak•Our hands look like other people hands.

•People are more like one another than like animals.

All people

have the same basic parts.

So what make these different traits?

•Genes tell your body how to make different traits. Genes are like instruction for the body.

•You got your genes from your birth parents. Genes tell your body how to work and grow.

•Genes come in pairs. One copy came from each parent. One from your mom. The other came from your dad. The copies are called alleles.

Gregor Mendel•The father of modern genetic

•Mendel studied dichotomous traits & how they are passed on to offspring

•Mendel demonstrated that the inheritance of certain traits in pea plants follows particular patterns, now referred to as the laws of Mendelian inheritance.

Mendelian Genetics

•2 possible "alleles" for each trait

•The combination one has (1 from mom, 1 from dad) is called your "genotype"

•2 matching alleles = "homozygous"

•2 different alleles = "heterozygous"

•In heterozygous individuals, the allele that is "expressed" (seen in individual’s appearance) is the "dominant" allele.

•The allele that is not expressed is the "recessive" allele

•The traits that are expressed make up your "phenotype"

•There are more than 2 alleles for some traits

•Most traits, in fact, are affected by more than 1 gene

Tongue Rolling

Genes play a part in tongue rolling. Many people roll their tongues easily. Others can roll their tongues a little. Some people cannot roll their tongues. Sometimes people can learn to roll their tongues with practice.

Rolling up edges (dominant trait) vs not rolling (recessive)

Traits•Sometime you need two alleles to get a

trait. Other times, you need just one allele.

You needed two alleles to have red hair.

Freckles

Freckles are traits. Freckles are spot on the skin.Pigment makes freckles. Pigment gives skin its color.It’s spread out in those without freckles. It’s clumped together in those with freckles.Pigment is a substance that gives color to something.

It takes just one freckle

allele to give a person

freckles.

Do you have

freckles?

Hair Color

Your gene tell the body to make certain pigments. Pigments color hair.

Hair traits

For many traits, one of a pair of genes takes control. But that’s not true for hair texture.

Some member of this family have straight

hair other have curly hair.

Ear Traits

Look at the bottoms of these ears. Can you tell how they are different?

Nose TraitsNoses come in many shapes. Gene help decide the shape of your nose.

Some noses are big. Some are small. Some curve out. Some are straight. Some even have turned-up end.

What is the shape of your nose? Is it curved or straight?

Which thumb is on top?

Left Brain, Right Brain

Dimples

Dimples are small dents in a person’s skin. These kids have dimples on her cheeks.

Dimples: Dimples (dominant trait) vs. No dimples (recessive trait)

Cleft chins

Cleft chins has a crease down the middle.Cleft chin is dominant over no cleft.

Hitchhiker’s thumb

Make a fist with one hand. Then hold put your thumb. Is it bent? Or is it straight? A thumb that bends like this one is a hitchhiker’s thumb.

Double-Jointed

Double-Jointed

This girl have double-

jointed elbow

Hands and Pinkies

Do you have hair on the middle parts of your fingers?

This man has some hair on the middle part of his fingers. Some people don’t have any hair.

Some traits are easy to see other traits are hidden

Can you smell this? People like some foods because of their smell.

Not everyone smells the same smells.

Your genes play a roll in what you can smell. Your genes let you smell certain scents. Hundreds of genes control our sense of smell. People have different alleles of these genes. So everyone smells things differently.

Asparagus

Most people smell a funny odor after they eat asparagus. And the smell is in a funny place. It’s in their pee! But some people smell nothing.

Scientists found that there are two different traits. The first trait is whether you make the odor. The second trait is whether you can smell it.

Some traits are easy to see other traits are hidden

Do you like broccoli?

Broccoli contain a chemical called Phenylthio carbamide (PTC)

This boy got an allele from his mom for tasting PTC. His dad passed along an allele that doesn’t react to PTC. The PTC tasting allele takes control. The boy taste PTC.

Other interesting facts about PTC

• -Only about half of Aboriginal peoples from Australia and New Guinea are tasters. Nearly 100% of indigenous Americans (i.e. Native Americans and Inuits) are tasters.

• -People who can taste PTC are more likely to be non-smokers and to not be in the habit of drinking coffee or tea. People who are super-tasters are more likely to find green vegetables bitter.

• Women, Asians, and African-Americans are all more likely to be super- tasters.

Your genes are part of what makes you

What special traits do you have?

Books•Unusual Traits: Tongue rolling, Special

Taste Sensors, and more/ Buffy Silverman

•Body Parts: Double-Jointedness, Hitchhiker’s Thumb, and More/ Buffy Silverman

•Facial Features: Freckles, Earlobes, Noses, and More/ Jennifer Boothroyd

•Hair Traits: Color, Texture, and More/ Buffy Silverman

Hair Color