Transcript Genetic+Disorder+Template

Color Blindness
Nancy Paguay & Zinani Harriot
2/1/2010
Period. 9/10
Are You Color Blind!?!?!?!
• http://www.nlm.nih.gov/medlineplus/ency/imagepages/9962.htm
Summary of Genetic Disorder
• This genetic disorder affects the perception of color. There are
some cases that may be a very mild difficulty of seeing colors,
while others have a total difficulty with seeing any color.
• symptoms:
• trouble seeing colors and the brightness of colors in the usual
way
• incapable of noticing the different shades of the same or
similar colors
• Interesting Facts:
• 3 types of color blindness
• most common is red-green vision defects. This type occurs
more in men than in women. The other two are blue-yellow
What chromosome is your disorder located on?
•May be more than one.
•Include a picture
Mode of Inheritance
• How would one acquire the genetic disorder?
(Yours may be sex linked, autosomal recessive or autosomal dominant)
• What does sex linked/x-linked, autosomal
recessive or autosomal dominant mean?
(What does autosomal refer to and what does recessive/dominant refer to?
What does “sex linked/x-linked)” refer to?)
• If your disorder is not well understood, explain.
• If the disorder has other modes of inheritance,
explain.
Explain what alleles are.
•How many alleles does each person have per gene
•Where they come from
•How we represent recessive or dominant alleles
-RR, rr, Rr
•What is dominance and recessiveness?
•Sex linked (x-linked) is represented with XR, or Xr, or Y
Make a punnett square to demonstrate the
probability per child depending on the parents
•Make more than one punnett square. Parents determine the ratio of
probability of offspring having the genetic disorder. Explain(see below) to the
class how the punnett square works.
•Female is on the left and father is represented on the top.
•*** Each punnett square represents the probability PER CHILD. Not all of the
children parents may have. ***
•homozygous dominant
•heterozygous dominant
•homozygous recessive
Use the same punnett square model to…
Explain probability using:
•Ratios
(must equal 4 because there are 4 possibilities)
homozygous dominant:heterozygous dominant:homozygous recessive
1
1GG
:
:
2
2Gg
:
:
1
1gg
•Percentages
(must equal 100 because there are 4 possibilities 25% each)
homozygous dominant:heterozygous dominant:homozygous recessive
25%
:
25%GG :
50%
50%Gg
:
:
25%
25%gg
Use the same punnett square to use as your
model to explain…
•What these letter mean! GG? Gg? gg?
If G represents the dominant allele GREEN and g represents the recessive allele
yellow, then we can assume that:
•Phenotype (what you SEE)
GG= GREEN
Gg= GREEN (yellow gene carrier)
gg = yellow
•Genotype (what is in the GENES)
GG= Homozygous dominant (GREEN)
Gg= Heterozygous dominant (GREEN)
gg = homozygous recessive (yellow)
Use the same punnett square model to…
Explain Genotype and Phenotype probability using:
•Phenotype
-Ratios- 3 GREEN : 1 yellow
- Percentages- 75% GREEN : 25% yellow
•Genotype
- Ratios- 1GG : 2 Gg : 1 gg
- Percentages- 25% GG: 50% Gg : 25%gg
Student Practice
Punnett Square Practice
You provide genes for the students:
only parents and student fill in the box
genotypes and phenotypes
Genotype:
Ratio:
Percentage:
Phenotype:
Ratio:
Percentage:
-When the students are finished, ask
them to share their answers with you.
Use the custom animation option to hide
the answers until student
theirs with you.
s have shared
Lastly, a 3 generation hypothetical Pedigree
Autosomal Dominant
Circle = female
Square = male
All White= homozygous recessive gene,
person is fine, has 2 copies of the “healthy”
gene
All Green= homozygous dominant, person
have disorder and 2 copies of the “bad” gene
Half Green/Half White= because this is a
dominant disorder (rules of dominance), the
person has the disease and only has one
copy of the “bad” gene and one copy of the
“healthy” gene.
Autosomal Recessive
White= Person is fine. May possibly
carry the recessive “bad gene.” Can
have one “health” and one “bad” gene
of two “healthy genes.”
Black= Person is affected. Has 2
“bad” genes.
X-linked
Color gene is “bad” on x chromosome
Color gene is “healthy” on x chromosome
Color gene is “healthy” on x chromosome
One gene is “bad”, one gene is
“healthy” on the x chromosome
Female is fine.
3 generations, (I: two parents II: 3 children and two spouses III: 4 children, any combo
( explain how to READ your punnett square)
Student Practice
(you provide generation I, 2, and 3)
Show a pedigree like this, but you fill in the rest using a different sample than the previous page.
You choose male and female, who is married to who (you have to add 2 spouses, and who has
children in the Generation III.
I
II
Example:
***Make a key: circle=
square=
shaded in=
not shaded in=
half shaded in=
III
Example:
***Ask 3 questions (type them on this page)
to make sure the students can analyze a
pedigree. (NO yes/no answers) 
1.
2.
3.