Genetics Part II

Nature vs. Nurture• What you are born with (your genes) only determines

part of how you will develop (nurture)• Gene Expression: Genes need to be “turned on” or

activated to create specific proteins. Genes are influenced by other genes and they are influenced by the environment

• Genetic Predisposition: May have the genetics for a trait, however, the gene/genes may never be activated. “At-Risk” … you may or may not even have the genes.

• You control part of your nurture HOWEVER some is out of your control (examples of nurture that is out of your control: Air quality, your mother’s diet while she was pregnant)

Vincent

• Genetically predisposed (99% probabilty) for heart failure

• Yet never has heart troubles• Assumes the identity of Jerome Morrow

Jerome

• Genetically “superior” – however still fails

In-Vitro Fertilization• Egg and sperm fertilized outside the human

body

Patterns of inheritance• Autosomal Dominant• Autosomal Recessive• Co-dominance / Incomplete Dominance• Multiple Alleles• X-linked• Non-Disjunctive disorders• Polygenetic traits

Polygenic traits• All the traits Mendel studied were

MONOgenetic (caused by a single gene)• Most traits are caused by multiple genes (POLY

= “MANY”) • Examples: Human height, intelligence

Sex-Linked Traits

• Gene located on the X Chromosome

- Color blindness- Hemophilia

You a man. Y. Yes that is correct!

Non-disjunction• Result of when during Meiosis (the formation

of gametes) chromosome pairs do not separate correctly – Thus Mendel’s law of segregation is broken

• Results in individuals with too many or too few chromosomes

• Examples: Downs Syndrome (Trisomy 21) and Turners Syndrome

Down Syndrome

Amniocentesis

• Using a needle amniotic fluid is removed from the women and tested• Much different from an ultrasound

or sonogram that only uses sound waves to create a picture of the baby

What is a Pedigree?

• A pedigree is a chart of the genetic history of family over several generations. A “family tree”

• Scientists or a genetic counselor would find out about your family history and make this chart to analyze.

Constructing a Pedigree

• Male

• Female

Connecting Pedigree Symbols

• Married Couple

• Siblings

Examples of connected symbols:

Example

• What does a pedigree chart look like?

Genetic DisordersAutosomal Recessive Disorders• Cystic Fibrosis• Sickle Cell Anemia• Tay-Sachs• PKU (Phenylketonuria)

Autosomal Dominant Disorders• Huntington’s• Marfan Syndrome

Simple Human Traits

Monogenetic with only two alleles: Dominate and Recessive

(Most human traits DO NOT fall into this category)

Cheek Dimples• Indentations along

side of mouth

• Dominant

Cleft Chin

• Indentation in chin

• Dominant

Earlobes• Can be free or attached

• Free are dominant, attached recessive

Face Freckles

Dominant

Hitchhiker’s Thumb• Ability to bend

thumb backwards at a 45-degree angle

• Recessive

Widow’s Peak• V-shaped point in

hairline

• Dominant

Morton’s Toe• Second toe longer

than first toe

• Recessive

Tongue Rolling

Dominant