What Are Traits?

What are Traits?• Traits are the characteristics that make a living

organism unique. They describe our appearance… or how we look to others.

• Our traits are inherited from our parents. That’s why sometimes people may say you look like your mother or your father, or even like your grandparents!

• Physical characteristics are called “phenotypes”. You’ll be able to remember this by looking at the first two letters in “physical” and “phenotype”.

Hair ColorDo you have blonde hair, brown hair, black hair or

maybe red hair? Hair color is a phenotype that is inherited. Genes are either “dominant” genes or “recessive” genes.

Look at the two hair colors below. Which one do you think is the “dominant” color and which is the “recessive” color?

recessive dominant

DimplesDimples are another phenotype that is

inherited. Do you have dimples when you smile? Look

around at your classmates. How many of them have dimples?

TonguesDid you know that tongues have their own

characteristics? Can you roll your tongue or is your tongue straight when you stick it out?

Check out the pictures below and see which one is like your tongue.

ChinsChins are another phenotype that is

easy to see. Do you have a cleft chin or a smooth chin?

Which one do you think is the most common or “dominant” trait?

Ear LobesEar lobes can be attached at the bottom or

not. If they are not attached, they appear to hang down more than the other type.

Which type of ear lobe do you have?

ThumbsHave you ever heard of a “hitch hiker”

thumb? This is another inherited physical trait, or phenotype.

Stick up your thumb. Does it stick straight up or does it tilt backwards?

Hitchhiker thumbStraight thumb

Hair LineWe looked at hair color but did you know the

way your hair grows is also inherited? Look at the front of your hair, at the hair line.

Is yours straight or do you have a point?

HandsHow many of you have seen the Star Trek

movies or TV shows? Remember the greeting Spock or other Vulcans used? This is also inherited.

Try it and see if you have “Vulcan” hands or “Earthling” hands!

GenotypeGenotype: the genetic makeup, or genes,

that determine the trait.Another word for gene is allele.We use letters to represent the alleles.Capital letters (like A, B, C) to represent traits

that are dominant.Lower case letters (like a, b, c) to represent

traits that are recessive.You inherit one allele (gene) from each

parent.

GenotypeExample – tongue rolling.Being able to roll your tongue is a dominant

trait. We’ll use the letter T to represent that.Not being able to roll your tongue is

recessive. We’ll use the letter t to represent that.

If you CAN roll your tongue, your genotype is either Tt or TT

If you CAN’T roll your tongue, your genotype is tt

Let’s Review!Phenotype = traits = physical characteristics

= what something looks like

Genotype = genes = alleles = letters = Tt

Dominant = shows up = capital letters = T

Recessive = masked / covered = lower case letters = t

Matching!PhenotypeGenotypeDominantRecessive

Allele

Another term for a gene

Traits that are covered by dominant traits

Your genetic makeup (alleles); like Tt or tt

Your physical features or traits

A trait that always shows

One more time!blue eyes, curly hair, dimples… genotypes or

phenotypes?Gg, aa, JJ… genotypes or phenotypes?B, H, U… dominant or recessive?b, h, u… dominant or recessive?When would the dominant trait show?

BB, Hh, ii, KK, Ll, rrWhen would the recessive trait show?

BB, Hh, ii, KK, Ll, rr