1. Warm Up
Find the two genotypes from the information given in questions 2,3,4,5, and 6 in the worksheet provided. (Ignore the squares)

2. Can you identify your own genotypes and phenotypes?
Hairline:
Widow’s peak is dominant to
straight hairline
Eye Shape:
Almond eyes
is dominant to round eyes

3. Eyelash Length:
Long eyelashes is dominant to
short eyelashes
Tongue Rolling:
CAN roll the tongue
is dominant to cannot

4. Hitchhiker’s Thumb:
Hitchhiker’s thumb is dominant to
straight thumb
Lip Thickness:
Thick lips
are dominant to thin lips

5. EQ: How can the outcome of genetic combinations be predicted?

6. Probability: the likelihood that a particular event will occur

7. How to complete a Punnett Square
1st Step = Identify the trait and what letter will represent it
What would be the possible outcomes for the offspring of a cross between pink flower (PP) and a white flower (pp)?
“P” and “p”

8. How to complete a Punnett Square
2nd Step = Assign the dominant/recessive trait for your letters
What would be the possible outcomes for the offspring of a cross between pink flower (PP) and a white flower (pp)?
P = PINK (dominant)
p = WHITE (recessive)

9. How to complete a Punnett Square
3RD Step = Determine the parental genotypes
What would be the possible outcomes for the offspring of a cross between Homozygous dominant pink flower and a Homozygous recessive white flower?
= PP
= pp

10. Let’s sum it up…..
1st = Identify the trait and what letter will represent it
2nd = Assign the dominant/recessive trait for your letters
3rd = Determine the parental genotypes.
4th = Now fill in your Punnett square

11. P P P P P P All Pink P = Pink p = White p p DAD = PP p MOM = pp p p p
Punnett Square practice… 1. What would be the possible outcomes for the offspring of a cross between Homozygous dominant pink flower and a Homozygous recessive white flower? P P
P = Pink
p = White
DAD = PP
MOM = pp P P p p p p P P p p
All Pink

12. 50% long F = Long f = Short DAD = Ff MOM = ff F f f Ff ff f Ff ff
2. Long fingers are dominant (F) to short fingers (f). Complete the Punnett square for a homozygous recessive mom and a heterozygous dad. What percentage of their offspring will have long fingers?
50% long
F = Long
f = Short
DAD = Ff
MOM = ff F f f Ff ff f Ff ff

13. 4/4 or 100% long L L L = Long L = Short DAD = LL MOM = ll l Ll Ll l Ll
3. In a plant, long stems are dominant (L) to short stems (l). If a homozygous dominant flower and a homozygous recessive plant are crossed, what would be the chance of having long stem offspring? L L
L = Long
L = Short
DAD = LL
MOM = ll l Ll Ll l Ll Ll
4/4 or 100% long

14. C C CC Cc Cc 1/4 or 25% curly c C = Straight c = Curly DAD = Cc
4. Straight hair (C) is dominant to curly hair (c). What would be the probability that a child would have curly hair if both parents are heterozygous? C c
C = Straight
c = Curly
DAD = Cc
MOM = Cc C CC Cc Cc c cc
1/4 or 25% curly

15. T Tt Tt 2/4 or 50% hitchhikers t T = Hitchhiker t = Straight tt
5. Having a hitchhiker's thumb is a dominant trait. If a woman with a straight thumb (recessive), has a child with a man who is heterozygous for the trait, what are the chances their child will have a hitchhiker's thumb? T t
T = Hitchhiker
t = Straight
DAD = Tt
MOM = tt Tt tt t Tt t tt
2/4 or 50% hitchhikers

16. P P Pp P PP Pp 0/4 or 0% green P = Purple p = White DAD = PP MOM = Pp
6. Purple is dominant to green in flowers. What are the chances of having green offspring if you mix a homozygous dominant flower with a heterozygous flower?
P = Purple
p = White
DAD = PP
MOM = Pp P P Pp P PP Pp pp p
0/4 or 0% green

17. Debrief:
In guinea pigs, short hair (S) is dominant to long hair (s). The cross between a guinea pig that is heterozygous short haired and a long haired guinea pig is shown to the right. Describe all of the information that can be determined from the Punnett Square. S s Ss ss