Transcript Genetic Diseases

Warm-Up / EOC Prep
1. External sources, such as radiation or chemicals, can
cause mutations in genes or entire chromosomes. For a
mutation to pass on to offspring, it must occur in a
a. sex cell
b. muscle cell
c. bone cell
d. brain cell
2. In snapdragons, the combined expression of both alleles
for flower color produces a new phenotype that is pink.
This illustrates incomplete dominance. The Punnett
square above shows that both the white and red
snapdragons are homozygous. Which of the following
would be the correct product from a cross between two
heterozygous pink snapdragons?
a. 2 red, 2 white
b. 2 red, 1 pink, 1 white
c. 1 red, 2 pink, 1 white
d. 1 red, 1 pink, 2 white
Agenda
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Warm-up
Notes
Genetic Disease Project
Clean-up
Cool-down
What is this called?
What is it used for?
What can you tell me about the
person?
Genetic Diseases
• DNA is the genetic material that passes from
generation to generation.
• DNA is organized into chromosomes
• Humans have two copies of 23 different chromosomes.
That makes 46 chromosomes total.
• Genes are segments of DNA that code for a
specific protein or trait.
Inheritance
• Mendalian Inheritance
– AA Homozygous dominant
– Aa Heterozygous dominant, carrier
– aa Homozygous recessive
• CoDominance, Incomplete Dominance
– Intermediate trait is expressed
• Sex-linked Inheritance
– Gene is only on X chromosome, males are affected
more than females because they only have on X
chromosome
• Nondisjunction
– Chromosomes get stuck together. One sex cell
ends up with more chromosomes, others end up
with less.
Mutations
• You can think of DNA as one long sequence of
letters.
• DNA polymerase is an enzyme that acts as a
“spell-checker”
• “Misspelling” of base pairs during DNA
replication result in mutations if they are not
caught by DNA polymerase
Types of Mutations
• Point mutation: Just one base is changed for
another base. This is just a single change in
amino acid.
• Insertion: a new base pair is added into the
sequence of DNA. This can result in a phaseshift, or all amino acids after that point are
different
• Deletion: a base pair is taken away or deleted
from the sequence. This can result in many
changes in amino acids.
Nondisjunction
When chromosomes
don’t separate
during meiosis
(super bad)
AMNIOCENTESIS
A technique used to
determine the genetic
traits of a baby before it is
born by taking a picture of
the chromosomes
A picture of the chromosomes is called a Karyotype.
What can you tell from the karyotype below?
Normal female (note the XX chromosomes)
What can you tell from the karyotype below?
Normal male (note the X and Y chromosomes)
Klinefelter Syndrome
• Chromosomes: 47, XXY
• Have male genitalia and internal ducts, but
underdeveloped testes
• Do not produce sperm
• Slight enlargement of the breasts
• Risk: 1 out of every 500 male births
Turner Syndrome
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Chromosomes: 45, X
Has female external genitalia
Underdeveloped ovaries
Short (under 5 feet)
Webbed Neck
Broad, Shield-like chest
Risk: 1 out of every 3000 female births
Down Syndrome
• A result of nondisjunction
• Chromosomes: AKA trisomy 21 (47, 21+); 3 copies of
the 21st chromosome
• Short
• Small round heads
• Protruding, furrowed tongues which cause mouth to
remain partially open
• Retarded (IQ below 70)
• Shortened life expectancy (<50)
• Prone to respiratory disease and heart
malformations
• Have 15x higher chance of getting leukemia
• Risk: Chance of having a baby with Down syndrome
goes up as the mother gets older
• REVIEW
• A chart that shows how traits are passed
within a family is called…
• pedigree
• In a pedigree, squares = _____ and circles =
______
• Males and females
• Name two sex-linked traits
• Hemophilia and colorblindness
• A picture of your chromosomes is called a…
• karyotype
• If a female has one normal x, and one
recessive x for colorblindness, will she be
colorblind?
• No, she is a carrier
Genetic Disease Project
• Instructions / Rubric- on the back of your
notes.
• Worth 1 Test Grade!
• DUE Tuesday, November 1st, 2011
Cool-Down
1- If you saw a baby with a webbed neck,
what genetic disorder do they most likely
have?
2- A karotype has 2 X and 1 Y chromosome.
What genetic disorder?
3- Which disorder results from nondisjunction
of chromosome 21?
Warm-up
Name the correct mode of inheritance…
1- A combination of the dominant and
recessive creates a new phenotype.
2- Neither allele is dominant, but both are
expressed at the same time.
3- The trait is found on either the X or Y
chromosome.