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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