Download Station 9 - Genetic Variations

Reporting Category 2
Mechanisms of
Genetics
Station 9
Genetic Variations
Essential Question – Bell Ringer
Hemophilia is a sex-linked trait that is
carried on the X chromosome. Why is
there a higher probability that males will
exhibit the characteristics of hemophilia
than females?
Essential Question – Bell Ringer
Hemophilia is a disease, carried only on the X
chromosome in humans, that prevents blood from clotting
properly. Males have one X and one Y sex chromosome,
so the hemophilia gene can appear on only one
chromosome in males—but males need only one
hemophilia gene to exhibit the characteristics of the
disease. Females have two X chromosomes and thus
have an increased chance of carrying the gene on one of
the chromosomes. However, the gene must be present on
both X chromosomes in order for females to exhibit the
characteristics of hemophilia. Therefore, males are more
likely than females to exhibit the characteristics of
hemophilia.
Pre-Preview Question
Genotypes for fruit fly wings
W = Normal Wings
w = wrinkled wings
• What are the phenotypes?
Ww - Normal Wings
ww - Wrinkled Wings
WW - Normal Wings
Pre-Review Question
• If Mary and Tom have a child, what is the
probability that they will have a boy?
X
Y
X
XX
1?
XY
2?
X
XX
3?
XY
4?
50% Boy
50% Girl
Pre-Review Question
• If Mary is a carrier for hemophilia (sex-linked,
recessive) and Tom does not have hemophilia,
what are the possible genotypes for their
offspring?
What is the
XH
XH
Xh
HXH
X1?
HXh
X
3?
Y
HY
X
2?
hY
X
4?
probability they
will have a child
with hemophilia?
1/4 chance of
having a child
with hemophilia
Lab Activities
• You will now go back to the lab and
complete the activities for today’s topic.
Practice
R – Red eyes
r – white eyes
W – normal wings
w – wingless
B – Normal bristles
b – no bristles
Y – Yellow body
y - black body
The white charts above contain the alleles for several fruit fly traits.
1. Cross the male and female for wings. What is the phenotypic ratio
for the F1 generation?
Practice
R – Red eyes
r – white eyes
W – normal wings
w – wingless
B – Normal bristles
b – no bristles
Y – Yellow body
y - black body
The white charts above contain the alleles for several fruit fly traits.
1. Cross the male and female for eye color (Remember this is a sex
linked trait). What is the phenotypic ratio for the F1 generation?
Practice
R – Red eyes
r – white eyes
W – normal wings
w – wingless
B – Normal bristles
b – no bristles
Y – Yellow body
y - black body
The white charts above contain the alleles for several fruit fly traits.
1. Complete a dihybrid cross for bristles and body color . What is
the phenotypic ratio for the F1 generation?
I need to be able to……..
• Analyze and make inferences about dominant
and recessive traits.
• Interpret and make predictions about genotypes
and phenotypes
• Determine and interpret phenotypic ratios.
• Understand the difference between Mendelian
and non-Mendelian traits.
• Use Punnett squares and other models to predict
the results of genetic crosses involving X-linked
traits.
• Interpret results and make predictions from
monohybrid and dihybrid crosses.
Post Review Question
Homozygous Dominant
Homozygous Recessive
Heterozygous
Which term above can be represented with the
following alleles?
AA
Homozygous Dominant
Post Review Question
Homozygous Dominant
Homozygous Recessive
Heterozygous
Which term above can be represented with the
following alleles?
Aa
Heterozygous
Post Review Question
Homozygous Dominant
Homozygous Recessive
Heterozygous
Which term above can be represented with the
following alleles?
aa
Homozygous Recessive
Post Review Question
Non-Mendelian Genetics
Incomplete Dominance
RR – Red
WW- White
If a red flower and a white flower are crossed, what will
the phenotype of the F1 generation be?
RW = Pink
Post Review Question
Non-Mendelian Genetics
Co Dominance
BB – Brown
WW- White
If a brown cow and a white cow are crossed, what will
the phenotype of the F1 generation be?
BW – brown and white spots