Bellwork: Tues. Jan. 10, 2017

1. Bellwork: Tues. Jan. 10, 2017 • Dominant trait: “masks” or covers up recessive traits. B = brown eyes b= blue eyesBb = Brown eyes • Recessive trait: will only appear without dominants. bb = blue eyes 3. Dominant traits: capitalized ( B, T, F…) Recessive traits: lower case ( b, t, f…)

2. Genotype:_______________________ of an organism. • Phenotype:_______________________ of an organism. • Homozygous: ___________________________ • Heterozygous: ___________________________ • Allele: ____________________________ ____________________________________

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

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

5. Crash course biology • https://www.youtube.com/watch?v=CBezq1fFUEA • https://www.youtube.com/watch?v=9SdCoNpDzqw

6. 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)

7. …So having dimples, and a cleft chin is rare because the versions of these genes are rare. And as long as there is noadvantage or disadvantage to having dimples, then the relative amounts of people with dimples won't change over time in a stable population. Dimples are dominantyet rare becausethe dimple geneversion 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. 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….

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

9. 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.

10. 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?

11. 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!

12. About 70% of people can taste PTC • Dominant/recessive trait in humans… • taste = dominantallele “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.

13. TT or Tt tt taste can’t taste

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

15. Some Terms: • Phenotype: physical appearance/ WHAT the trait “causes”. • YOU CAN OBSERVEphenotypic 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. 

16. 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

17. 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

18. Incomplete dominanceis 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 arepink. 

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

20. 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).

22. 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)

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

24. 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

26. 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

28. 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

29. 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

30. 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

31. 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

32. 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 dominantmale 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:_____:______

34. 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).

36. 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?

37. Smooth Axial Constricted Terminal https://www.youtube.com/watch?v=mnSkz8s-b44

39. https://www.youtube.com/watch?v=pk0CHH7Prtw