Color Vision Deficiency

•Is a condition where the retina (eye) is unable to distinguish colors correctly•It can either affect seeing the red and green (most common), blue and yellow, or all colors (monochromacy)•1 out of 12 men are affected and 1 out of 100 women have this condition

•It is sex linked

•Genetic red-green color blindness affects men much more often then women because the genes for the red and green color receptors are located on the X chromosome of which men have one and women have two

Meaning concerning characteristics that are determined by genes carried on the sex chromosomes (on the X chromosome in particular)

Genetic

Other modes of inheritance include:DiabetesGlaucomaMacular degenerationAlzheimer’s DiseaseParkinson’s DiseaseMultiple Sclerosis

Chronic AlcoholismLeukemiaSickle Cell AnemiaCertain Medications used to treat heart problems, infections, and psychological problemsAgingChemical Exposure such as fertilizers

Each person has two alleles

Come from our parents

Capital letters are dominant and lower case letters are recessive genes D for color blindness

dfor non color blindnessDd for carrier of color blindness

The dominant gene and recessive genes carry the same traits, but the dominant trait overpowers the recessive

XD

Xd

XD Y

•homozygous dominant•heterozygous dominant•homozygous recessive

XDXD XDY

XdXD XdY

1 : 2 : 1

Homozygous Dominant Heterozygous Dom Homozygous Res

25% : 50% : 25%

Phenotype

D for color blindness

d for non color blindness

Dd for carrier of color blindness

XD

Xd

XD Y

XDXD XDY

XdXD XdY Genotype

D for homozygous dominant (color

blind)

d for heterozygous dominant (non-color

blind

Dd for homozygous recessive (carrier

of color blind gene)

Genotype-Ratios [3 with color blind gene : 1 without]-Percentages [75% with color blind gene: 25% without]

XD

Xd

XD Y

XDXD XDY

XdXD XdY

Phenotype-Ratios [1 xdxD : 2 xDxD xDy : 1 xdy]- Percentages [25% xdxD : 50% xDxD xDy : 25% xdy]

XDXd

XDXd

XDY

XDY

XD

XD

Xd Y

= normal vision male (healthy)

= color blind male (bad)

= normal vision female (healthy)

= normal vision female with recessive gene (one bad one healthy)

= normal vision male (healthy)

= color blind male (bad)

= normal vision female (healthy)

= normal vision female with recessive gene (one bad one healthy)

Questions:1.How many people have one or more unhealthy vision gene?

Questions:2.Why are the two 2nd generations girls carriers?

Questions:3. How many Homozygous Dominant people are present?

About 8% of all men are suffering from color blindness.

A father can’t pass his red-green color blindness on to his sons.

If a woman is red-green colorblind, all her sons will also be colorblind.

When using color correcting lenses you are wearing two differently colored lenses in your eyes.

More women than men are carriers of color blindness, even though they are not colorblind themselves.

Police officer, firefighter, and airline pilot are the most famous jobs which require normal color vision.

Color blindness is also called Daltonism, after the scientist John Dalton.

Monochromacy—also called achromatopsia—means you have only one type of color receptors (cones) in your eyes.