Genetic
Disorders
ESSENTIAL QUESTION:
How does a mutation affect the
life of an organism?
What are some options that
scientists have to predict the
possibility of genetic diseases in
infants?
Do all mutations cause a change in
the physical appearance of an
organism?
REVIEW
Changes in the gene code change
_______________
the protein
that is made
A change in the genetic code =
________________
mutation
Many genetic
___________
result
DISORDERS
from
changes in the DNA code
so _________________
NON-FUNCTIONING
proteins are produced.
KINDS OF MUTATIONS
Mutations that produce changes in a single gene =
GENE MUTATIONS
_________________
Mutations that produce changes in whole chromosomes =
_____________________
CHROMOSOMAL
MUTATIONS
CHROMOSOMAL
MUTATIONS
____________________________:
Change in the ______________
or
structure
____________
number of chromosomes
Ex:
Inversion of
chromosome
12
Do you recognize this family?
*Hint: They are from a TV show
They are the Roloff family from
TLC’s show Little People Big World
How are the members of this family
the same?
How are they different?
Same
Different
facial
features,
hair color
etc.
height
Some family members (including
the parents) exhibit the
characteristic short stature of
Achondroplasia, a dominant
genetic disorder that results in a
form of dwarfism.
EXPLORATION ACTIVTIY:
How is it possible for Matt
and Amy (the parents) to
have a child like Zach
with Achondroplasia,
dominant genetic
disorder, and three
children who do not have
the disease?
DID YOU QUICKLY THINK, Since some of the Roloff
children do not exhibit dwarfism, what do we know
about Matt and Amy’s genes for Achondroplasia?
THAT’S RIGHT!!!
Matt and Amy both have an Aa
genotype. This would allow
them to have children who
exhibit dwarfism as well as
children of normal height.
Dwarfism: Aa or AA
Normal height: aa
DID YOU KNOW?
1. As the occurrence of infectious and nutritional diseases
decreases in developed countries, genetic diseases have come to the
forefront.
2. At least one-third of the children in pediatric hospitals are
there because of hereditary disorders.
3. Chromosomal mutations account for about half of all firsttrimester miscarriages.
4. A total of about 7% of the population suffers from some type of
genetic disorder.
GENETIC DISEASES: inherited
disorders reflecting gene mutations or
abnormalities in chromosome
structure or number, which result in a
functional or anatomical change.
Examples:
-changes that cause deformities (cleft lip)
-metabolic change (phenylketonuria “pku”)
-structural changes (albinisim)
How are genetic disorders
transmitted or inherited?
Genetic diseases can be inherited in a manner similar to that
of normal traits. These diseases include single-gene disorders
that are autosomal or sex-linked.
Autosomal
Sex-linked
means that the gene is
present in a chromosome
pair other than the sex
chromosomes
means that the gene is
located on a sex
chromosome
Types of Genetic
Diseases
Sex-linked
Autosomal recessive
Autosomal dominance
Sex-Linked Genes
Pattern of inheritance is located on the Xchromosome or the Y- chromosome
Y is much smaller
Therefore, there are more X-linked disorders/traits
What numbers do you See?
Ex. Colorblindness
X-linked disorder
Most common in ?
Males (1/10)
Females (1/100)
AUTOSOMAL RECESSIVE
DISORDER
A mutation that causes a protein to be NONFUNCTIONAL would appear _________
Recessive to the
normal working allele.
• EXAMPLES:
• Phenylketonuria (PKU)
• Tay-Sachs Disease
• Cystic Fibrosis
The following is simply an example to assist with your
understanding:
Ex: Phenylketonuria (PKU)
CAUSE:
ENZYME
breaks down an
Mutation in gene for an ___________
that __________
amino acid
___________
called phenylalanine
X
X
Build up causes ________________________
MENTAL RETARDATION
Phenylketonuria (PKU)
ALL babies are ________
tested
____
for PKU before they
leave the hospital.
Treatment:
LOW in phenylalanine to
Need a diet _____________________
extend life and ______________
mental
PREVENT
retardation
amino acid
If phenylalanine is an _____________,
what type of foods should PKU patients avoid?
PROTEINS !
__________________
Autosomal Dominant
Disorders
• A mutation that codes for a new protein whose
action masks the normal allele appears as a
dominant
_____________
mutation. HENCE,
•
DOMINANT
_________________________ GENETIC
DISORDERS:
• Examples:
•
Huntington’s Disease
•
Achondroplasia (Roloff family )
Analyzing Karyotypes
What can you tell by this karyotype?
Karyotype
Organized profile of a human’s chromosomes
Chromosomes are paired by
centromere location
banding pattern
Size
REVIEW
Chromosomes that determine
the sex of an organism =
Sex chromosomes
_________________
All other chromosomes =
autosomes
_________________
Humans have two sex chromosomes
X
Y
44
and _____ autosomes
EXPLANATION
ACTIVITY
• Karyotyping Activity
Analyzing Karyotypes
What can you tell by analyzing this karyotype?
Karyotype Analysis:
Chromosomal Disorders
Nondisjunction- occurs when either homologous
chromosome fails to separate during meiosis
Results abnormal # of chromosomes in gametes
Trisomy = 1 extra homologous chromosome (3)
Polysomy = more than 1 extra
Monosomy = only 1 chromosome
Examples: Down syndrome, Klinefelter syndrome,
Turner Syndrome
Find the chromosome that results from
nondisjunction below
That’s right, the sex
chromosome has an
extra Y. Trisomy,
polysomy, or
monosomy?
ELABORATION
ACTIVITY
• Predict the genetic disorder
by constructing a karyotype.