Station 9

1
Station 9
Reporting Category 2 Mechanisms of Genetics

• Genetic Variations

2
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?

3
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 malesbut 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.
4
Pre-Preview Question

• Genotypes for fruit fly wings
• W Normal Wings w wrinkled wings
• What are the phenotypes?
• Ww -
• ww -
• WW -

Normal Wings
Wrinkled Wings
Normal Wings
5
Pre-Review Question

• If Mary and Tom have a child, what is the
  probability that they will have a boy?

X Y
X 1? 2?
X 3? 4?
50 Boy 50 Girl
XX
XY
XY
XX
6
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 probability they will have a child
with hemophilia?
XH Y
XH 1? 2?
Xh 3? 4?
XHXH
XHY
XHXh
XhY
1/4 chance of having a child with hemophilia
7
Lab Activities

• You will now go back to the lab and complete the
  activities for todays topic.

8
Practice
R Red eyes W normal wings B Normal
bristles Y Yellow body r white eyes w
wingless b no bristles y - black body

• The white charts above contain the alleles for
  several fruit fly traits.
• Cross the male and female for wings. What is the
  phenotypic ratio for the F1 generation?

9
Practice
R Red eyes W normal wings B Normal
bristles Y Yellow body r white eyes w
wingless b no bristles y - black body

• The white charts above contain the alleles for
  several fruit fly traits.
• Cross the male and female for eye color (Remember
  this is a sex linked trait). What is the
  phenotypic ratio for the F1 generation?

10
Practice
R Red eyes W normal wings B Normal
bristles Y Yellow body r white eyes w
wingless b no bristles y - black body

• The white charts above contain the alleles for
  several fruit fly traits.
• Complete a dihybrid cross for bristles and body
  color . What is the phenotypic ratio for the F1
  generation?

11
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.

12
Post Review Question
Homozygous Dominant Homozygous
Recessive Heterozygous
Which term above can be represented with the
following alleles? AA
Homozygous Dominant
13
Post Review Question
Homozygous Dominant Homozygous
Recessive Heterozygous
Which term above can be represented with the
following alleles? Aa
Heterozygous
14
Post Review Question
Homozygous Dominant Homozygous
Recessive Heterozygous
Which term above can be represented with the
following alleles? aa
Homozygous Recessive
15
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
16
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