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Color Vision Deficiency. Danie C. and Yrbenka A. Period 2. Co lor Vis io n De fi ci en cy 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)
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Color Vision Deficiency Danie C. and Yrbenka A. Period 2
ColorVisionDeficiency • 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
X-Chromosome • 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
Mode of Inheritance Sex linked • 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: • Diabetes • Glaucoma • Macular degeneration • Alzheimer’s Disease • Parkinson’s Disease • Multiple Sclerosis • Chronic Alcoholism • Leukemia • Sickle Cell Anemia • Certain Medications used to treat heart problems, infections, and psychological problems • Aging • Chemical Exposure such as fertilizers
alleles • Each person has two alleles • Come from our parents • Capital letters are dominant and lower case letters are recessive genes Dfor color blindness dfor non color blindness Dd for carrier of color blindness • The dominant gene and recessive genes carry the same traits, but the dominant trait overpowers the recessive
Punnett Square XD Y XDXD XDY XD • homozygous dominant • heterozygous dominant • homozygous recessive XdY XdXD Xd
Ratios 1:2:1 Homozygous DominantHeterozygous DomHomozygous Res Percentages 25%:50%:25%
Phenotype Dfor color blindness dfor non color blindness Ddfor carrier of color blindness XD Y XD XDXD XDY Xd XdY XdXD Genotype D for homozygous dominant (color blind) dfor 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] Phenotype -Ratios [1 xdxD : 2 xDxD xDy : 1 xdy] - Percentages [25% xdxD : 50% xDxD xDy : 25% xdy] XD Y XDY XDXD XD XdXD XdY Xd
Genes Xd Y XDXd XDY XD XDXd XDY XD
Pedigree = normal vision male (healthy) = color blind male (bad) = normal vision female (healthy) = normal vision female with recessive gene (one bad one healthy)
Student Practice 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? = normal vision male (healthy) = color blind male (bad) = normal vision female (healthy) = normal vision female with recessive gene (one bad one healthy)
DID YOU KNOW….. Random Facts Monochromacy—also called achromatopsia—means you have only one type of color receptors (cones) in your eyes. Color blindness is also called Daltonism, after the scientist John Dalton. When using color correcting lenses you are wearing two differently colored lenses in your eyes. Police officer, firefighter, and airline pilot are the most famous jobs which require normal color vision. About 8% of all men are suffering from color blindness. If a woman is red-green colorblind, all her sons will also be colorblind. More women than men are carriers of color blindness, even though they are not colorblind themselves. A father can’t pass his red-green color blindness on to his sons.
