Define polygenic inheritance10.3.1

Defining polygenic inheritance

• A characteristic which is controlled by one or more gene.

• “Multi-factorial” inheritance– Mendel

• Multi-gene inheritance

Polygenic conditions

• Skin color• Obesity• Cancer• Diabetes

Things that can affect polygenic conditions

• Environment– Ex. A person who tans may have darker skin.

Explain that polygenic inheritance can contribute to

continuous variation using two examples, on of which must be human skin color.

10.3.2

Polygenic Inheritance

• Explains how genes can continuously vary• Examples of this are a person’s height, blood

type, and skin color

Polygenic inheritance differentiates skin color

Polygenic inheritance affects blood type

4.3.12Deduce the genotypes and

phenotypes of individuals in pedigree charts.

Genotype and phenotype

• Genotype: The entire set of alleles in an organism. Usually written with letters

• Phenotype: Alleles that include all characteristics based on the genotype.

• Ex: tall short – TT tt– T t

– Tt/ Tall

Co-dominance• Co dominant Alleles: A pair

of alleles that are both affect the phenotype when present in a heterozygote.

• Example: red flower + white flower= pink flower

• To write co dominance the main letter should relate to the gene and the suffix to the allele*draw on board

Heterozygote: having two different alleles for the same gene

Pedigree Chart

• Pedigree Chart: Pedigree charts are used to record blood lines in families. They can be used to figure the probability of an offspring and the donor of certain diseases.

• : affected male• : affected female• : male• : female

Inheritance

• Autosomal Dominant– You only need to get the abnormal gene from one

parent in order for you to inherit the disease.• Autosomal Recessive– Two copies of an abnormal gene must be present

in order for the disease or trait to develop.

Inheritance

• Sex-linked Dominance– A single abnormal gene on the X chromosome can cause a sex-

linked dominant disease.

• Sex-linked Recessive– An abnormal gene on both X chromosomes causes a sex-linked

recessive disease

Disease and Pedigree• Color Blindness: A condition

that is caused by genetic factors.

• Is determined by a carrier of the recessive trait

• Females have two chromosomes, so to have color blindness she would need two recessive alleles.

• The male has only one X chromosome and just needs one recessive allele to be affected.

Pedigree Bingo! • 1. Obtain a blank pedigree chart, and an orange, yellow, red, and blue colored

pencil.• 2. Color in the circles for the Grandmother. Make them a variety of your colors.• 3. Then do the same for the Grandfather using different colors.• 4. Next, close your eyes and randomly pick a colored pencil. Choose 3 examples

from Grandmother and 3 examples from Grandfather.• 5. Color in these circles for their first child, a daughter. Then complete these

steps again for the rest of their children.• 6.Next, look at the son and his partner. Make the partner have all 6 circles red.• 7. Randomly pick colors from the Son and his partner. Because his partner has

all red, 3 circles will be red, and 3 circles will randomly be chosen from the father.

• 8. Do this for all 3 children.• 9. Analyze the results.

Results!– Red = high risk of heart disease

– Orange = medium risk of heart disease

– yellow= low risk of heart disease

– Negative risk of heart disease

Works cited• http://www.sciencelearn.org.nz/Contexts/Uniquely-Me/

Science-Ideas-and-Concepts/Genotype-and-phenotype

• http://www.hobart.k12.in.us/jkousen/Biology/inccodom.htm

• http://genealogy.about.com/od/free_charts/a/forms.htm

• http://www.correlagen.com/patients/x-linked_dominant.jsp

• Http://learn.genetics.utah.edu