TAY-SACHS DISEASEGENETIC DISORDERS

MIGUEL URBINO & JAZZ RANDALLPERIOD 3

OTHER PEOPLE MAY HAVE THIS DISEASE AND BE RESPECTFUL WHEN REACTING

PLEASE KEEP IN MIND

SUMMARY• Very rare• This disorder is inherited• It destroys the nerve cells in your brain and

spinal cord• Recessive gene • Mostly occurs in infants• Survival rate is up to 3 to 4 years of age

INFANTS

• Lose their motor skill ability such as turning over, sitting, and crawling

• Exaggerated startled reactions to loud noises • Not easily noticed at first• Go through seizures, vision and hearing loss,

intellectual disability, and paralysis

CHROMOSOME 15

The HEXA- Chromosome 15Tay Sachs is caused by mutations in the HEXA gene

MODE OF INHERITANCE How would one acquire Tay Sachs? -if the parents of an offspring are both a carrier of the disease then

you get full Tay Sachs What does sex linked/x-linked, autosomal recessive or autosomal

dominant mean? - If a disease is autosomal dominant, it means you only need to get the gene

from one parent in order for you to inherit the disease. - An autosomal recessive disorder means two copies of the gene must be

shown in order for you to inherit the disease or trait. - Sex-linked means that a single gene on the X chromosome can cause the

disease. This can happen in boys and girls but in the case of males they may not survive.

ALLELES• An allele is an alternative form of a gene that is located at a specific

position on a specific chromosome• 2/per gene• They come from our parents whether they carry the trait or not• Recessive= r Dominate= R• Dominant means you are more likely to inherit something from your

parents• Recessive means you can inherit it from your parents but it is a less

likelihood you will

PUNNETT SQUARESFATHER'S GENES

T t

MOTHER'S T TT Tt

GENES t Tt tt

FATHER'S GENES

T T

MOTHER'S T TT TT

GENES t Tt Tt

FATHER'S GENES

T T

MOTHER'S T TT TT

GENES T TT TT

FATHER'S GENES

t t

MOTHER'S T Tt Tt

GENES t tt tt

Ratios: 1 : 2 : 11TT : 2Tt : 1t

FATHER'S GENES

T t

MOTHER'S T TT Tt

GENES t Tt tt

ANALYZING PUNNETT SQUARES

Percentages: 25% : 50% : 25%

25%TT : 50%Tt : 25%t

ANALYZING PUNNETT SQUARES (CONTINUED)

What do the letters mean?FATHER'S GENES

T t

MOTHER'S T TT Tt

GENES t Tt ttPhenotype: (Physical Color)TT= RedTt = Yellowtt = Green Genotype:

TT = Homozygous DominantTt = Heterozygous Dominant

tt = homozygous recessive

ANALYZING PUNNETT SQUARES (CONTINUED)

Genotype and PhenotypeFATHER'S GENES

T t

MOTHER'S T TT Tt

GENES t Tt tt

Phenotype: (Physical Color)Ratios- 1 Red : 2 Yellow : 1 GreenPercentages- 25% Red : 50% Yellow : 25% Green

Genotype:Ratios- 1 TT : 2 Tt : 1 tt

Percentages- 25% TT : 50% Tt : 25% tt

PHENOTYPE:Ratio-Percentages-

FATHER'S GENES

t T

MOTHER'S t

GENES T

PRACTICE PUNNETT PROBLEMS

GENOTYPE:Ratio- Percentages-

3 GENERATIONHYPOTHETICAL PEDIGREE

LEGEND:• Square = Male• Circle = Female• Red = TT• Yellow = Tt• Green = tt

PEDIGREE PRACTICELEGEND:• Square =• Circle =• Shaded =• Half Shaded = • Not Shaded =

ANALYZING PEDIGREES Read the Questions CAREFULLY

1. Is it possible for a TT and Tt to have a tt off-spring?2. Is it possible for a Tt and Tt to have a TT off-spring?3. Is it possible for a tt and TT to have a TT off-spring?

THANK YOU FOR YOURATTENTION AND COOPERATION

MIGUEL URBINO & JAZZ RANDALLPERIOD 3