Warm-Up / EOC Prep1. 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

• 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 phase-shift, 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.

When chromosomes don’t separate during meiosis

(super bad)

Nondisjunction

A technique used to determine the genetic

traits of a baby before it is born by taking a picture of

the chromosomes

AMNIOCENTESIS

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• 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.