Bellwork Tues Jan 8 2019 1 Dominant trait

Bellwork: Tues. Jan. 8, 2019 1. Dominant trait: “masks”/covers up recessive traits. B = brown eyes b= blue eyes Bb = Brown eyes 2. Recessive trait: only appears without dominants. bb = blue eyes 3. Dominant traits: capitalized ( B, T, F…) Recessive traits: lower case ( b, t, f…)

4. Genotype: ____________ of an organism. 5. Phenotype: ____________ of an organism. 6. Homozygous: ______________ 7. Heterozygous: ______________ 8. Allele: ________________________________

Dimples are dominant Human Traits Lab Cleft chin is dominant Wet ear wax is dominant… I have the recessive “dry” ear wax

Crash course biology • https: //www. youtube. com/watch? v=CBezq 1 f FUEA • https: //www. youtube. com/watch? v=9 Sd. Co. Np Dzqw

What is dominant? What is recessive? • A trait that is considered “dominant” masks recessive traits. In other words, it “dominates” the recessive. • A recessive trait requires no dominant traits to be present. These recessive traits will only appear without dominants. • Dominant traits are capitalized (IE: A, X, F, etc) • Recessive traits are lower case (IE: a, x, f, etc)

…So having dimples, and a Dimples are dominant yet rare because the dimple gene version is rare… the same goes for cleft chin… cleft chin is rare because the versions of these genes are rare. And as long as there is no advantage or disadvantage to having dimples, then the relative amounts of people with dimples won't change over time in a stable population. So dominant does not mean more common Dominant just means that form of the trait will “win out” over the recessive form. But… if the form of the gene is advantageous to a population, more Individuals with than form will survive to pass on that gene to their offspring. So for some other genes it seems like almost everyone has that dominant trait….

• • Tasters in class: Non-tasters in class: Total: Percent tasters:

Accidental Taster in 1931 Chemist Arthur Fox sat at his Du. Pont Company lab bench, mixing a powdered chemical. Accidentally a bit of the powder blew into the air. Fox and another scientist got some of the chemical into their mouths. Dr. Fox's colleague exclaimed how bitter the powder tasted. Fox was surprised -- he had been much closer to the chemical, but he tasted nothing at all.

Both men tasted the chemical again. To Fox it was still tasteless, but his co-worker insisted it was very bitter. Fox handed out crystals of the chemical, which were not poisonous, to his friends, family members and fellow scientists and asked them if they tasted anything. Some people, like Fox, tasted nothing; others found the chemical somewhat bitter or intensely bitter. What was going on?

Since then, the chemical phenylthiocarbamide (PTC) has been used to detect genetic variation in tasting abilities. Studies soon after the incident in Fox's lab showed that there is a genetic component that influences how PTC tastes! Scientists found that people were much more likely to find PTC bitter if other members of their family also found it bitter. The evidence was so strong for a genetic link that PTC tasting ability was used as evidence in paternity tests before DNA tests were available!

About 70% of people can taste PTC Dominant/recessive trait in humans… taste = dominant allele “T” for the gene Cannot taste = recessive allele “t”. But since you get an “allele” (gene) from each parent… if you can taste the PTC you COULD be either TT or Tt • If you cannot taste the PTC then you are tt… • If you listen and “get” this concept NOW the weeks after break will be a lot easier AND you can compare traits with relatives during break. • • •

TT or Tt taste tt can’t taste

• http: //www. telegraph. co. uk/science/evolution/6019200/Scientists-discover-that. Neanderthals-hated-Brussel-sprouts. html

Some Terms: • Phenotype: physical appearance/ WHAT the trait “causes”. • YOU CAN OBSERVE phenotypic traits: Eye color, hair color height, nose shape eye shape…: • In this lab, you will determine some of your own phenotypic traits and figure out some of your possible genotype(s) for these traits.

• You only need one copy of a dominant gene in order to see a dominant phenotypic trait, but you need two copies of a recessive gene in order to see a recessive phenotypic trait. • A dominant phenotypic trait is represented capitol letter like B for brown eyes • A recessive phenotypic trait is represented lower case letter like b for blue (or light color) eyes BB = Bb = bb = You must have two recessives to “exhibit” (show) the recessive trait

• Your Genotype (gene make-up) “letters” can be: • homozygous dominant: BB, (phenotype: brown) or • homozygous recessive: bb , (phenotype: blue) or • Heterozygous Bb (phenotype: brown) • …write the capital letter first

• http: //learn. genetics. utah. edu/content/begin/ traits/ • http: //www. thetech. org/genetics/ask. php? id=188

Hairline: A widow’s peak (W) hairline comes to a point in the center of the forehead. It is dominant trait (genotype can be WW or Ww) to having a straight hairline (w) has to be ww).

Eye shape: Almond-shaped eyes are dominant (A) to round-shaped eyes (aa). round shaped eyes (a) (notice the white visible under the iris) almond shaped eyes (A)

• Eyelash length: Long eyelashes are dominant (E) to short eyelashes (e). Short eyelashes (e) ee long eyelashes (E) so EE or Ee

Tongue-rolling: The ability to roll the tongue is dominant (C) to the inability to roll the tongue (c). Can roll tongue (C) so CC or Cc Can’t roll tongue (c) cc

Thumb: The hitchhiker’s thumb (thumb tip bends backward more than 30 degrees) is dominant (B) to a straight thumb (b). Straight thumb (mine) (b) I’m bb Hitchhiker’s thumb (B) so… BB or Bb

• Lip Thickness: Thick lips are dominant (L) to thin lips (l). Thick lips (L) so… LL or Ll Thin lips (l) have to be ll

• Incomplete dominance is a special case when the heterozygous phenotype “mixes” (or is intermediate), and not DOMINATED by dominant gene. Snapdragon flowers are an example of this: , homozygous dominant flowers are red homozygous recessive flowers are white, and heterozygous flowers are pink.

• Hair Texture: Curly hair is incompletely dominant (HH) to straight hair (SS). Those who have wavy hair are intermediate (HS). Curly Hair HH Wavy Hair HS Straight Hair SS

• Inter-eye Distance: Close-set eyes are incompletely dominant (DD) to eyes set far apart (FF). Medium-set eyes are DF. Close set eyes: DD Wide set eyes FF

Lip Protrusion: Protruding lips are incompletely dominant (PP) to nonprotruding lips (NN). Slightly protruding lips are intermediate (PN). Protruding lips PP slightly protruding lips PN nonprotruding lips NN

Bellwork: Wed. Jan. 11, 2016 In seals, the gene for whisker length is controlled by 1 gene. The dominant allele (W) = long whiskers the recessive allele (w) = short whiskers. If a homozygous dominant male seal and homozygous recessive female seal mate, what is the probability that their pups will have long whiskers? Draw a Punnett Square & show the cross: ______ X ______ and show the: genotypic ratio: ______ phenotypic ratio: ______

Check only one: Trait Hairline W w Eye Shape A a Eyelash Length E e Tongue Dexterity C c Thumb B b Lip Thickness L l Hair Texture H / S Inter-Eye Distance D / F Lip Protrusion P / N Your Possible Phenotype Genotype(s) Dominant Recessive Intermediate

Hairline: A widow’s peak (W) hairline comes to a point in the center of the forehead. It is dominant trait (genotype can be WW or Ww) to having a straight hairline (w) has to be ww). Eye shape: Almond-shaped eyes are dominant (A) to round-shaped eyes (aa). Eyelash length: Long eyelashes are dominant (E) to short eyelashes (e). Tongue-rolling: The ability to roll the tongue is dominant (C) to the inability to roll the tongue (c). Thumb: The hitchhiker’s thumb (thumb tip bends backward more than 30 degrees) is dominant (B) to a straight thumb (b). Lip Thickness: Thick lips are dominant (L) to thin lips (l). Hair Texture: Curly hair is incompletely dominant (HH) to straight hair (SS). Those who have wavy hair are intermediate (HS). Inter-eye Distance: Close-set eyes are incompletely dominant (DD) to eyes set far apart (FF). Medium-set eyes are DF. Lip Protrusion: Protruding lips are incompletely dominant (PP) to nonprotruding lips (NN). Slightly protruding lips are intermediate (PN).

Answer the questions and turn in 1. Which traits do you have that are dominant? (list them) 2. Which traits do you have that are recessive? (list them) 3. Which of your traits are incompletely dominant (mixed)? 4. Which of your traits do you share with one or more of your classmates? 5. What determines your traits (i. e. , how do you acquire them)? 6. Which traits are more common (dominant or recessive)? Why?

END

Smooth Constricted Axial Terminal https: //www. youtube. com/watch? v=mn. Skz 8 s-b 44

Trait Hairline (widow’s/straight) Eye Shape Almond/round Eyelash Length Long/short Tongue Dexterity Roll/not roll Thumb Lip Thickness Hair Texture Inter-Eye Distance Lip Protrusion Check only one: Your Phenotype Possible Genotype(s) Dominant Recessive Intermediate

• https: //www. youtube. com/watch? v=pk 0 CHH 7 Prtw