Transcript Human Genetic Disorders - Madison Central High School

Key Concepts
•What
are two major causes of genetic
disorders in humans?
•How
traits?
•How
do geneticists trace the inheritance of
are genetic disorders diagnosed and
treated?
Key Terms
Genetic disorder
 Karyotype
 pedigree
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Causes of Genetic Disorders
Genetic disorder – abnormal condition
that a person inherits through genes or
chromosomes
 Some are caused by mutations in the
DNA of genes
 Others are caused by changes in the
overall structure or number of
chromosomes

Cystic Fibrosis
Body produces abnormally thick mucus
in the lungs and intestines
 The thick mucus fills the lungs making
it hard to breathe
 Caused by recessive
 allele on one chromosome
that is the result of a
mutation in which 3 base
pairs are removed from a
DNA molecule
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Sickle- Cell Disease
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Affects hemoglobin, protein in
blood that carries O2
When o2 concentrations are low
blood cells have a sickle shape
The sickle shape can clog blood
vessels and cannot carry as much
O2 as normal shaped red blood
cells
The allele is codominant with
normal allele
A person with 2 sickle shaped
alleles will have the disease
One allele and the person will
produce both normal and sickle
shaped cells. These people will
not usually have symptoms of
the disease
Hemophilia
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A person’s blood clots
very slowly or not at all
Do not produce one of the proteins needed
for normal blood clotting
Small bumps and bruises may cause
internal bleeding that can’t be controlled
Caused by a recessive allele on the X
chromosome
Sex-linked disorder – occurs more
frequently in males
Down Syndrome
Trisomy 21
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Have an extra copy of
chromosome 21 (instead of
a pair the person has 3 copies)
Most often occurs when
chromosomes fail to separate
properly during meiosis
Have some degree of mental
retardation.
Heart defects are also common,
but can be treated
Pedigrees
Chart used to trace
the inheritance of
traits in humans
 Can track ordinary
traits or a genetic
disorder

Managing Genetic Disorders
Doctors used to only have Punnett
Squares and pedigrees to help predict
genetic disorders
 Now they have tools such as karyotypes
to help diagnose genetic disorders
 People with genetic disorders can be
helped through medical care, education,
job training, and other methods

Karyotypes
Picture of all the chromosomes in a cell
 Arranged in pairs
 Can reveal whether a person has the
correct number of chromosomes
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Genetic Counseling
A couple with a family history of a
genetic disorder can go to a genetic
counselor for advice
 Help couples understand their chances
of having a child with a
particular genetic disorder
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Dealing with Genetic
Disorders
Medical treatments help people with some
disorders
 Ex. Physical therapy helps remove mucus
from the lungs of people with cystic
fibrosis
 Taking Folic Acid helps people with sicklecell disease make more red blood cells
 Education and job training helps people
with Down Syndrome find work in a
variety of places of employment
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