Crazy Traits

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?

Traits

• 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)• Traits are determined by genes. For each inherited

trait, you get one form of the gene (an allele) from each of your parents.

• 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.

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 factors: 1. the genotypes of your parents2. the allele from each parent you inherit.

Crazy Traits• The alleles you inherit from each parent are

determined by chance. • In this investigation, you will play a game that

will help you learn about inheritance.

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”

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.

Determining trait genotypes for your creature

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

• The genotype of each parent could be Tt, TT, or tt. We are choosing to have parents with the Tt genotype for each trait.

Determining the genotype for each trait

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

• You will also need the green 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. • Place the egg and sperm coins in the cup. • Shake the cup and toss the two coins onto the lab

table. • The side that lands up on each coin represents the

sperm and egg that unite during fertilization.

Determining the genotype for a trait

• 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.

Adaptation Survivor

1. Environment Cards will be displayed on this screen. 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.