TOPIC: Genetics AIM: What is a Pedigree Chart?

TOPIC: Genetics AIM: How can pedigree charts be used to trace a trait from one generation to the next? DO NOW: How does Down Syndrome occur?

Hypertrichosis is a genetic disorder that triggers uncontrolled hair growth due to physical defects like non-functioning of endocrine gland, infections, mutation, malnutrition, drugs or hereditary factors. Also called werewolf syndrome, it leads to hair formation in unwanted areas generally exempting the hands, feet and eyes. Werewolf syndrome is a rare condition which affects only one person among ten billions. Hypertrichosis either originates during birth or develops after a person grows up especially on the verge of puberty. It is believed to be a genetic disorder that is inherited or occurs as a result of spontaneous mutation.

Pedigree Chart Visual tool for following a trait through generations of a family

Predicts the probability that a baby will be born with a specific trait.

Symbols used in pedigree charts A marriage with five children, two daughters and three sons. The eldest son is affected by the condition. Eldest child  Youngest child Normal male Affected male Normal female Affected female Marriage © 2007 Paul Billiet ODWS

How do you read a pedigree chart? Not shaded = does NOT have the trait. Half-shaded = “carrier” (has 1 allele). Completely shaded = has the trait (homozygous – both alleles for the trait).

Generations are identified by Roman numerals. II III IV

How many individuals are represented in this pedigree chart? A pedigree chart of a family showing 20 individuals

Pedigree Charts “Genetic Family Tree” Now what must the genes be for (1) and (2)?? Both must be “Bb” for them to have a child (5) with “bb” blue eyes. What about child (3)? This child must be either BB or Bb, you can’t tell until they have their own children someday. Click to other remaining genotypes. Shaded normally indicates a recessive trait, for example all shaded symbols would be “bb” for simple eye color Bb Bb Bb Bb bb Bb B_? B_? Bb bb bb Circles = females Square = males Normally shaded symbols indicate a recessive trait.

3. Which child is married? Does the spouse have attached ear lobes? 1. This pedigree shows the inheritance of attached earlobes. Which parent has attached ear lobes? The father 2. How many children do the parents have? Which child has attached ear lobes? 3 children, Child #1 has attached ear lobes. 3. Which child is married? Does the spouse have attached ear lobes? Child # 3 is married. Her spouse does not have attached earlobes. 4. Do any of this child’s children have attached ear lobes? Yes, the son has attached earlobes.

What does this pedigree chart show? How many people are unaffected “carriers”? How many people are affected by the disorder? How many carriers are female?

What does this pedigree chart show? How many people are unaffected “carriers”? How many people are affected by the disorder? Can we tell if the disorder is dominant or recessive? How many generations are represented?

Royal Hemophilia Pedigree

II-1 II-2 Female

pure 50%

Review 1. Another name for a pure genotype like TT is ______. 3.  Another name for hybrid offspring like Tt is ____. 4.The genetic makeup of an organism is called its ___. 5.The appearance of an organism is also called its ___.

6. R = round r = wrinkled Give the allele combinations for the following genotypes: Heterozygous round seeds Homozygous round seeds Wrinkled seeds Give the phenotypes for the following genotypes: 4. RR 5. Rr 6. Rr

7. An organism having two different alleles for a trait is called a. heterozygote   b. homozygous dominant     c. genotype    d. monohybrid cross    8. Mendel hypothesized that each trait is controlled by a factor, now called a a. gene    b. mate   c. hybrid    d. dominance    

9. The phenotype of an organism a. represents its genetic composition b. reflects all the traits that are actually expressed c. occurs only in dominant pure organisms d. cannot be seen

10. If an individual possesses two recessive alleles for the same trait, the individual is said to be a. homozygous for the trait             b. haploid for the trait c. heterozygous for the trait           d. mutated

11. The human sperm cell contains 44 chromosomes and two X chromosomes 46 chromosomes 44 chromosomes, one X chromosome, and one Y chromosome 23 chromosomes

12. Put the following terms in order from largest to smallest: Chromosomes Nucleus DNA genes

13. A person who is heterozygous for type A marries a person who is homozygous for type O. What is the chance of them having a child with blood type O?