Download - COLOR BLINDESS
COLOR BLINDESS
By John Daniel “JD” Fogarty and Jude Kwaku PokuJanuary 28
Period 3
SUMMARY OF COLOR BLINDNESS
Color Blindness is defined as the inability to distinguish between certain colors.
Color Blindness occurs when there is an absence of color-sensitive pigments in the cone cells of the retina, or the nerve layer at the back of the eye.
Color Blindness symptoms can vary. Some people may have trouble seeing red, while others may have a difficulty with blue. These kinds of deficiencies are not so serious. For a person who has a full on color deficiency, the only colors they can see are different shades of black, white, and grey.
COLOR BLINDNESS TESTS
What numbers do you see?
COLOR BLINDNESS CHROMOSOME
Color blindness is X-linked recessive in the mother’s chromosome. It is more common in males than females.
MODE OF INHERITENCE
People acquire the genetic disorder of color deficiency through birth. A color defective male always inherits the deficiency though his mother who usually has normal color vision, but is a carry of the defect.
ALLELES
PUNNETT SQUARES Punnett squares are used to show the probability
of receiving a genetic disorder from a parent.
GG GgGg gg
Gg
G g
Mom
Dad
PUNNETT SQUARE PROBABILITY
Ratios:1: 2:
1 1 GG 2 Gg
1ggPercentages:25%: 50%
25%25% GG 50% Gg
25% gg
GG Gg
Gg gg
G
g
G g
WHAT ARE PUNNETT SQUARES? Uppercase letters represent dominant
genes while lowercase represent recessive genes, which are always over powered by the dominant genes.
A red gene represents a gene that is not a carrier of color blindness, while a green gene represents a gene that is a carrier.
GG Gg
Gg gg
G
g
G g
PHENOTYPES: WHAT YOU SEEGG=REDGg=RED (Green Gene Carrier)gg= Green
GENOTYPES: WHAT IS IN THE GENESGG= Homozygous dominant (RED)Gg= Heterozygous dominant (RED with Green)gg= Homozygous recessive (Green)
PUNNETT SQUARES GENOTYPES AND PHENOTYPES
Phenotype:Ratio: 3 RED:1 GreenPercentages: 75% RED:25% GreenGenotype:Ratio: 1 GG:2 Gg:1 ggPercentages: 25% GG: 50% Gg:
25% gg
GG Gg
Gg gg
G
g
G g
MORE PUNNETT SQUARES!
AA
AA
Aa aa
A AAa
TT TTTt tt
T tTt
XX XyXy xy
X yXx
PRACTICE TIME!Genotype:Ratio: 1XX:2Xy:1xyPercent: 25% XX:50%Xy:25%xyPhenotype:Ratio: 2 RED:2 GreenPercent: 50% RED:50% Green
XX XyXy xy
X yXxTotal Percentage for color blindness:
50%