Crazy Traits - Frey Scientific · Crazy Traits • In this investigation, you will play a game that...

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Crazy Traits

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Key questions • What are traits? • How do traits vary in a species? • How are traits inherited? • What role does chance play in an

organism’s heredity?

Try This… • When you are told, place the small piece of

paper on your tongue. • What happened? • How many in the classroom can taste

something? • How many cannot taste anything?

PTC

• Phenylthiocarbamide

http://learn.genetics.utah.edu/content/begin/traits/ptc/

Traits

• A trait is a characteristic that makes you unique.

• Traits are determined by genes which are located on your chromosomes.

PTC Tasting

• The ability to taste PTC is an inherited trait. There are two forms of the trait:

• Let T = taster (dominant form) • Let t = nontaster (recessive form) • Your phenotype is either taster or nontaster • Your genotype is TT or Tt if you are a taster, or tt if

you are a nontaster.

Genotype • Combination of alleles that determine a

particular trait • For example: Tt is a genotype for the PTC

tasting trait Phenotype

• Expression of a genotype • For example: The phenotype for Tt is “taster”

Crazy Traits • Your traits are determined by the genes you

inherit from your parents. • For each gene, you get at least one allele

from your mother and one allele from your father.

Crazy Traits • The alleles you end up with are determined

by two variables: 1. The GENOTYPES of your parents 2. WHICH allele each parent passes to you

• The alleles you inherit are determined by chance or PROBABILITY.

Crazy Traits • In this investigation, you will play a game that

will help you learn about inheritance. • Locate the coins inside the Crazy Traits tin

cup.

Your creature’s gender

• Find the egg coin (x on both sides) • Find the sperm coin (x on one side, y on the

other) • Flip the coins together to determine the

gender of your creature. • Record this in the table provided – see next

slide for example

Determining trait genotypes for your

creature • Members of this species have the following

traits: main body, foot, leg, skin, arms, hands, beak, eyes, eyebrows, ears, wings, antenna.

• You will flip sperm and egg coins to determine the allele for each trait your creature inherits from each parent.

• In this activity, we will assume that both parents have the same genotype for all traits (Tt).

Determining the genotype for each trait

• You will need the egg coin with a capital T on one side and a lower case t on the other side.

• You will also need the sperm coin with a capital T on one side and a lower case t on the other side.

• The first trait you will roll for is skin color. • Flip the egg and sperm coins on your table. • The side that lands up on each coin represents the

sperm and egg that unite during fertilization.

Determining the genotype

• Record the allele from each parent and genotype in columns 2, 3, and 4 of the first row of Table 1.

• Repeat this procedure for traits 2 through 13. • See the next slide for an example.

Determining the genotype

Stop and Think

a. What information do the letters on the sperm and egg coins indicate: alleles, genotype, or phenotype?

Alleles. Both alleles together represent the

genotype.

Stop and Think

b. For the sperm coin, what are the chances of getting a T or getting a t? State your answer as a fraction or a percent.

1/2 or 50%.

Stop and Think

c. For the egg coin, what are the chances of getting a T or getting a t? State your answer as a fraction or a percent.

1/2 or 50%.

Stop and Think

d. When both coins are flipped at once, what are your chances of getting each of the following combinations: TT, Tt, or tt? State your answer for each as a fraction and a percent.

Building your creature

• Once you have completed columns 2 through 4 of Table 1, use Table 2 (next page) to look up the phenotype for each trait. Record the phenotype for each trait in column 5 of Table 1.

Building your creature

• Once you have completed Table 1, select the correct body parts to build your creature. See parts list on next slide.

Creature Building Tips

1. Orient the body for either male or female (which orientation do you think is male? Female?)

2. Place the skin on the smooth side of the body. 3. Attach the head. 4. Attach the leg. 5. Place foot on the stand. 6. Insert the leg into the foot and stand. 7. Attach the rest of the body parts.

Thinking about what you observed

a. Examine the creatures. Do any of them look exactly alike? Why or why not?

• Some look similar, but no two are alike. For two to look exactly alike, every single flip of all three coins would have to be the same for both creatures. That seems very unlikely.

Thinking about what you observed

b. How does this investigation explain why siblings may resemble each other, but never look exactly alike (unless they are identical twins)?

• Since siblings share the same parents they will likely share many of the same traits. With the huge amounts of traits possible for humans the probability of all of them matching from sibling to sibling is very small.

Thinking about what you observed

c. Count the number of males and number of females. Does the number of each match the chances of getting a male or female in the game? Why or why not?

• Not exactly because the sample is small. Larger samples yield results that are closer to the average.

Thinking about what you observed

d. Which trait(s) are examples of complete dominance? • Eyebrows, beak, ears, leg, foot, arms, hands,

antennae, antenna shape, wings, and gender. e. Which trait(s) are examples of incomplete

dominance? • Skin color and tail. f. Which trait(s) are examples of codominance? • Eye color.

Presenter
Presentation Notes
Incomplete dominance - Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype. Examples: In cross-pollination experiments between red and white snapdragon plants, the resulting offspring are pink. The dominant allele that produces the red color is not completely expressed over the recessive allele that produces the white color. �Codominance -

Thinking about what you observed

g. What are they odds that another creature has all the exact same traits as your creature?

• Tally up the odds of each specific trait your creature has – Careful, not every trait has the same odds. For Example: Red Eyes – 1/4 Stop and Go eyes – 3/4

e. Once you have all the odds for each trait, multiply the individual odds to get the total odds for your creature.

½ x 1/3 x ¾ x ¾ x ¼ x ¾ x ½ x ¼ x ¼ x ¾ x ¾ x ¼ x ½ x ¼ = 243/25,165,824 = 1/103,563

Presenter
Presentation Notes
Incomplete dominance - Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype. Examples: In cross-pollination experiments between red and white snapdragon plants, the resulting offspring are pink. The dominant allele that produces the red color is not completely expressed over the recessive allele that produces the white color. �Codominance -

Adaptation Survivor

1. Draw Environment Cards. For each card, your creature can: thrive (+1 point); be pushed closer to extinction (-1 point); or have no effect (0).

2. Watch out for Catastrophe Cards! 3. When you earn a score of -3, you become

extinct! 4. Play until there is one survivor left.

Thank you for coming!!

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