The family tree of genetics Pedigree Charts The family tree of genetics A quick refresher for the teacher on important terms: Autosomal gene- a gene found on any chromosome except for the sex chromosome. These are chromosomes numbered 1-22. X-linked gene- a gene found on a chromosome designated as a sex chromosome (X or Y). Dominant- Refers to an allele that is expressed phenotypically and masks any recessive counterpart. Recessive- An allele that is not phenotypically expressed when its counterpart is dominant.

Pedigree What do you think of when you read the above word? Dog food Family Lineage inheritance

Pedigrees are family trees that explain your genetic history. Pedigrees are used to find out the probability of a child having a certain trait in a particular family. This summary will help reiterate the important parts of this lesson. [Created by Lauren Almaguer, CDC Science Ambassador, 2004.]

Pedigree Charts These charts are used to show how family members are related to each other, using genetics, and it includes atleast two generations. Scientists or a genetic counselor would find out about your family history and make this chart to analyze.

Phenotypes are used to infer genotypes on a pedigree. Phenotype is the physical characteristic or trait that is inherited. You find the phenotype by looking at the genotype. The genotype is represented by upper and lower case letters based on the genes inherited from parents.

Pedigree Chart that shows how a trait and the genes that control it are inherited in a family.

Normally those with a trait are shaded in while those without a trait are left clear. If an organism has a trait but does not show the trait in its phenotype, They are a carrier and the circle or square is only shaded halfway.

Pedigree -Females are represented bycircles -Males are represented by squares -Shading is an individual with the trait -Individual carrying the trait (a carrier)

Marriage / mating is represented by a line connecting two individuals. Offspring are represented by connecting the middle of the parents with lines drown vertically up and down(in order of birth rom left to right). 1 2 3 4

Finding a Gene on the Chromosome Map We can examine inheritance in a family by constructing a pedigree. In this family certain members (in black) have Whirling disorder.

Finding a Gene on the Chromosome Map How do scientists find the genes responsible for a hereditary disease in a family? Think of all the genes in a person’s genome as puzzle pieces in a jigsaw puzzle. Each piece represents a different gene. Because all humans have the same set of genes in the same order, every family member has the same basic jigsaw puzzle arrangement. Shown here is a generic human jigsaw puzzle.

Make a pedigree based on the following passage about freckles. Although Jane and Joe Smith have dimples, their daughter, Clarissa, does not. Joe’s dad has dimples, but his mother and his sister, Grace, do not. Jane’s dad, Mr. Renaldo, her brother, Jorge, and her sister, Emily, do not have dimples, but her mother does.

Mrs Renaldo Mr. Renaldo Mrs. Smith Mr. Smith Emily Jorge Jane Joe Grace Clarisa

Andy, Penny, and Delbert have freckles, but their mother, Mrs Andy, Penny, and Delbert have freckles, but their mother, Mrs. Cummins, does not. Mrs. Biodano, Mrs. Cummins’s sister, has freckles, but her parents, Mr. And Mrs. Lutz, do not. Deidra and Darlene Giordano are freckled, but their sister, Dixie, like her father, is not freckled.

A pedigree is a chart for tracing genes in a family.

If the phenotype is more common in males, the gene is likely sex-linked.

Your Pedigree Make a Pedigree based on your family. Include the following: 3 generations One trait (hair, dimples, eye color, etc) Names Key