Human Traits Lab Dimples are dominant Cleft chin is dominant Wet ear wax is dominant I have the recessive dry ear wax Bellwork: Mon. Nov. 30, Dominant trait: masks or covers up recessive traits. B = brown eyes b= blue eyes Bb = Brown eyes 2.Recessive trait: will only appear without dominants. bb = blue eyes 3. Dominant traits: capitalized ( B, T, F) Recessive traits: lower case ( b, t, f) 4.Genotype is the _______________________ of an organism. 5.Phenotype is the _______________________ of an organism. 6.homozygous is ___________________________ 7.heterozygous is ___________________________ 8.An allele is ____________________________ ____________________________________ Human Traits Lab Dimples are dominant Cleft chin is dominant Wet ear wax is dominant I have the recessive dry ear wax 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) Dimples are dominant yet rare because the dimple gene version is rare the same goes for cleft chin So dominant does not mean more common Dominant just means that form of the trait will win out over the recessive form. So having dimples, and a 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. 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 DuPont 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 tt taste cant taste Neanderthals-hated-Brussel-sprouts.htmlNeanderthals-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 Incomplete dominance is a special case when the heterozygous (BIG LETTER, little letter Bb) 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. traits/traits/ Hairline: A widows 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) almond shaped eyes (A) (notice the white visible under the iris) 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 Cant roll tongue (c) cc Thumb: The hitchhikers thumb (thumb tip bends backward more than 30 degrees) is dominant (B) to a straight thumb (b). Hitchhikers thumb (B) so BB or Bb Straight thumb (mine) (b) Im 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 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 Check only one: Trait Your Phenotype Possible Genotype(s) DominantRecessiveIntermediate Hairline W w X Eye Shape A a X Eyelash Length E e X Tongue Dexterity C c X Thumb B b X Lip Thickness L l X Hair Texture H / S Inter-Eye Distance D / F Lip Protrusion P / N Hairline: A widows 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 hitchhikers 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). Check only one: TraitYour Phenotype Possible Genotype(s) DominantRecessiveIntermediate Hairline (widows/straight) Eye Shape Almond/round Eyelash Length Long/short Tongue Dexterity Roll/not roll Thumb Lip Thickness Hair Texture Inter-Eye Distance Lip Protrusion 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? Bellwork: Tues. Dec. 1, 2015 Name the independent variable and dependent variable the two experiments. https://www.youtube.com/watch?v=qtLnBz6lbRQ https://www.youtube.com/watch?v=qtLnBz6lbRQ 1. I.V:_____D.V.:_____ 2. I.V:_____D.V.:______ https://www.youtube.com/watch?v=qtLnBz6lbRQ Name the independent variable and dependent variable the two experiments. 1. I.V:D.V.: 2. I.V:D.V.: Smooth Constricted Axial Terminal https://www.youtube.com/watch?v=pk0CHH7 Prtw https://www.youtube.com/watch?v=pk0CHH7 Prtw Bellwork: Wed. Jan. 7, 2013 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 dominate 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:_____:______