Transcript What Are Traits?

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 Color
 Do 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
Dimples
 Dimples are another phenotype that is inherited.
 Do you have dimples when you smile? Look around
at your classmates. How many of them have
dimples?
Tongues
 Did 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.
Chins
 Chins 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 Lobes
 Ear 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?
Thumbs
 Have 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?
Straight thumb
Hitchhiker thumb
Hair Line
 We 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?
Hands
 How 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!
Genotype
 Genotype: the genetic makeup, or genes, that
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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.
Genotype
 Example – 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!
Phenotype
Genotype
Dominant
Recessive
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
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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, rr
 When would the recessive trait show?
BB, Hh, ii, KK, Ll, rr