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					Punnett squares
 The tool which uses
 the combination of
alleles to predict the
probability of traits
     showing up in
       offspring.
    Green eyes are
  dominant and yellow
  eyes are recessive.
 The genotype of two
insects are Gg and Gg.
Complete a Punnett square!
    G             g

G   GG        Gg

g   Gg            ??
        ?? = gg
What % of the young
 would have green
      eyes?
        75%
   Yellow eyes?
        25%
If B=black and b=brown and
two wolves are heterozygous
Bb and homozygous bb what
   would their young be?



 Complete a Punnett square!
    B    b

b   Bb   bb

b   Bb   bb
What % of young would
 be black and what %
   would be brown?
     Black = 50 %
     Brown = 50 %
B=Brown eyes which are
 dominant, b=blue eyes
  which are recessive
What are the alleles of
  the parents for the
    following chart?
    B    b

B   BB   Bb

b   Bb   bb
The parents would be
 Bb and Bb and both
  would have brown
        eyes!
Curly hair is dominant,
and a couple have curly
  hair. How many of
 their babies will have
      curly hair?
A. All of the babies
B. Probably most of
the babies
C. None of the
babies
 Answer - B
What percent of your
genes come from each
       parent?

    50%
What % of genes
come from each
 grandparent?

 25%
 If green snake skin
   is dominant and
 yellow is recessive,
what are the alleles
of the parent snakes
  for the following:
    G    G

g   Gg   Gg

g   Gg   Gg
 Homozygous (GG)
 green


Homozygous (gg) yellow
  How many different
Punnett squares can you
       think of?
   If big ears are
  dominant and both
      parents are
homozygous dominant,
what percent of babies
  will have big ears?
    E    E

E   EE   EE

E   EE   EE
100%
Three fingers is dominant
      and five fingers
  recessive. If mom is
homozygous dominant and
  dad is heterozygous,
 what percent of young
 will have three fingers?
    F    F

F   FF   FF

f   Ff   Ff
100%
 Big noses are dominant
    and little noses are
   recessive. If Dad is
homozygous dominant and
    mom is homozygous
 recessive, what percent
 of children will have big
          honkers?
    N    N

n   Nn   Nn

n   Nn   Nn
100%
  Short is dominant and
 tall is recessive. If dad
is heterozygous dominant
 and mom is homozygous
 recessive, what percent
  of the children will be
       short and tall?
     S      s’

s’   Ss’   s’s’

s’   Ss’   s’s’
50% short
 50% tall
Long neck is dominant and
 short neck is recessive.
 If dad is heterozygous
   dominant and mom is
 heterozygous dominant,
   what percent of the
  children will have long
 necks and short necks?
    N    n

N   NN   Nn

n   Nn   nn
75% Long

25% Short
   Short tongues are
 dominant and long are
  recessive. If mom is
 homozygous recessive
 and dad is homozygous
recessive, what percent
of the children will have
     long tongues?
    t    t

t   tt   tt

t   tt   tt
100%
   CROSSING TWO TRAITS
• CROSS A HOMOZYGOUS TALL ,
  HETEROZYGOUS GREEN PEA PLANT
  WITH A HOMOZYGOUS SHORT,
  HOMOZYGOUS YELLOW PLANT.

• TTGg X ttgg
         4                             8
               3                   7
         TTGg        x          ttgg
               1                  5
                            6
     2                                       4
               1     2            3
               TG   Tg           TG         Tg
5
                                 TtGg      Ttgg
tg           TtGg    Ttgg


6                               TtGg       Ttgg
             TtGg   Ttgg
tg

7            TtGg   Ttgg        TtGg       Ttgg
tg

8            TtGg   Ttgg        TtGg       Ttgg
tg
             1                2               3              4
           TG                Tg              TG             Tg
5
tg       X
        TtGg
                              X
                             Ttgg            X
                                            TtGg            X
                                                            Ttgg

 6
tg        X
         TtGg                X
                             Ttgg           X
                                            TtGg             X
                                                            Ttgg

7
tg        X
         TtGg                X
                             Ttgg            X
                                            TtGg            X
                                                            Ttgg


8
tg        X
         TtGg                X
                             Ttgg
                                             X
                                            TtGg              X
                                                            Ttgg



Genotypes and percentages     TtGg = 8/16          Ttgg = 8/16
Phenotypes and percentages    Heterozygous Tall    Heterozygous Tall
                              Heterozygous Green   Homozygous Yellow
Thank you

				
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posted:12/9/2011
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