predicting phenotypes and genotypes heterozygous – is there a predictable result when both parents...
TRANSCRIPT
Predicting Phenotypes and Genotypes
Heterozygous – Is there a predictable result when both parents are heterozygous?
Homozygous – is there a predictable result when both parents are homozygous?
Types of Questions1) Green eyes/ yellow eyed fruit flies
2) Brown/black wolves
3) Find parents genotypes
4) Curly haired babies
5) Parents and grandparents
6) Snakes
7) Donkeys
8) Noses
9) Short/tall
10) Short neck/long neck
11) Short/longue tongues
Punnett Squares
The tool which The tool which uses the uses the
combination of combination of alleles to predict alleles to predict the probability of the probability of traits showing up traits showing up
in offspring.in offspring.
1) Green eyes are dominant and yellow eyes are recessive. The genotype of two
insects are Gg and Gg.
Complete a Punnett square!
Genotype and Phenotypes
Genotypes
What are the chances that the offspring will have the following genotypes?
GG?
Gg?
gg?
Phenotypes
Give the percentages of the offspring which will have the following phenotypes:
Green eyes _____Yellow eyes _____
Answer
When you have tried it…
G
Gg
GgGG
g
G
g
??
?? = gg
What % of the young would have green
eyes?
Yellow eyes?75%
25%
What % of the young would have GG? (1 out of 4) 25%
Gg? 50%gg? 25%
2) Show the result of crossing (mating/breeding) two wolves.
The female is heterozygous Bb and the male is homozygous bb.
Complete a Punnett square!
What % of young would be black and what %
would be brown?
Black = 50 %Brown = 50 %
Answer
When you have tried it…
B
Bb
bbBb
b
b
b
bb
3) B=Brown eyes which are dominant
b=blue eyes which are recessive
What are the alleles of the parents for the
following chart?
B
Bb
BbBB
b
B
b
bb
Answer
When you have tried it…
The parents would be Bb and Bb and both would have
brown eyes!
4) Curly hair is dominant, and a
couple both have curly hair. What are the chances that their
children will have curly hair?
A. All of the babies B. At least 75% of the babies
C. At least 50% of the babies
D. None of the babies
Answer
After you have tried it….
C
Cc
CcCC
c
C
c
cc
Even if the parents were heterozygous for curly hair…
75% of the offspring would have curly hair (CC or Cc – both of these genotypes give the phenotype of curly hair)
5) What percent of your genes come from
each parent?
50%
5) ContinuedWhat % of genes come from each grandparent?
25%
6) If green snake skin is dominant and yellow is recessive, what are the alleles of the parent snakes
for the following:
Answer
When you are ready…
G
Gg
GgGg
g
g
G
Gg
Homozygous (GG) green
Homozygous (gg) yellow
7) In donkeys, if big ears are dominant and
both parents are homozygous
dominant, what percent of babies will
have big ears?
E
EE
EEEE
E
E
E
EE
100%
Answer
When you are ready…
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
Ff
FFFF
f
F
F
Ff
100%
8) 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
Nn
NnNn
n
n
N
Nn
100%
9) 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
Ss’
s’s’Ss’
s’
s’
s’
s’s’
50% short
50% tall
10) 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
Nn
NnNN
n
N
n
nn
75% Long
25% Short
11) 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
tt
tttt
t
t
t
tt
100%
Thank you