Download tay-sachs disease - Tay

GENETIC DISORDERS
TAY-SACHS DISEASE
MIGUEL URBINO & JAZZ RANDALL
PERIOD 3
PLEASE KEEP IN MIND
OTHER PEOPLE MAY HAVE THIS DISEASE
AND BE RESPECTFUL WHEN REACTING

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 15
Tay 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 SQUARES
FATHER'S GENES
MOTHER'S T
GENES
t
T
t
TT
Tt
Tt
tt
FATHER'S GENES
MOTHER'S T
GENES
t
FATHER'S GENES
MOTHER'S T
GENES
T
T
T
TT
TT
TT
TT
T
T
TT
TT
Tt
Tt
FATHER'S GENES
MOTHER'S T
GENES
t
t
t
Tt
Tt
tt
tt
ANALYZING PUNNETT SQUARES
FATHER'S GENES
MOTHER'S T
GENES
Ratios:
1
1TT
:
:
2
2Tt
25%
25%TT
t
T
t
TT
Tt
Tt
tt
:
:
1
1t
:
:
50%
50%Tt
Percentages:
:
:
25%
25%t
ANALYZING PUNNETT SQUARES
(CONTINUED) FATHER'S GENES
What do the letters mean?
MOTHER'S T
GENES
Phenotype: (Physical Color)
TT= Red
Tt = Yellow
tt = Green
t
T
t
TT
Tt
Tt
tt
Genotype:
TT = Homozygous Dominant
Tt = Heterozygous Dominant
tt = homozygous recessive
ANALYZING PUNNETT SQUARES
(CONTINUED) FATHER'S GENES
Genotype and Phenotype
MOTHER'S T
GENES
t
T
t
TT
Tt
Tt
tt
Phenotype: (Physical Color)
Ratios- 1 Red : 2 Yellow : 1 Green
Percentages- 25% Red : 50% Yellow : 25% Green
Genotype:
Ratios- 1 TT : 2 Tt : 1 tt
Percentages- 25% TT : 50% Tt : 25% tt
PRACTICE PUNNETT PROBLEMS
FATHER'S GENES
t
MOTHER'S t
GENES
PHENOTYPE:
RatioPercentagesGENOTYPE:
RatioPercentages-
T
T
3 GENERATION
HYPOTHETICAL PEDIGREE
LEGEND:
• Square = Male
• Circle = Female
• Red = TT
• Yellow = Tt
• Green = tt
PEDIGREE PRACTICE
LEGEND:
• Square =
• Circle =
• Shaded =
• Half Shaded =
• Not Shaded =
ANALYZING PEDIGREES
1.
2.
3.
 Read the Questions CAREFULLY 
Is it possible for a TT and Tt to have a tt off-spring?
Is it possible for a Tt and Tt to have a TT off-spring?
Is it possible for a tt and TT to have a TT off-spring?
THANK YOU FOR YOUR
ATTENTION AND COOPERATION   
MIGUEL URBINO & JAZZ RANDALL
PERIOD 3