Transcript Crazy Traits

Crazy Traits
Key questions
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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 parents
2. 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.
Determining the genotype
for a trait
• 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
• 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.
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
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Orient the body for either male or female (which
orientation do you think is male? Female?)
Place the skin on the smooth side of the body.
Attach the head.
Attach the leg.
Place foot on the stand.
Insert the leg into the foot and stand.
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.