Transcript Human Genetic Disorders PPT

Human Genetic Disorders
Key Concepts
What are two major causes of genetic disorders in
humans?
How do geneticists trace the inheritance of traits?
How are genetic disorders diagnosed and treated?
Key Terms
 Genetic disorder
 Karyotype
 pedigree
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- quick facts
 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
Sickle- Cell Disease
 Affects hemoglobin, protein in blood
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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
 A person’s blood clots
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very slowly or not at all
Does 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
 Have an extra copy of chromosome 211
(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
 In the past, doctors only had 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
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
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 sickle-cell disease
make more red blood cells
 Education and job training helps people with Down
Syndrome find work in a variety of places of
employment