Heredity

• In the past, traits were thought to be carried by the blood.•We now know what genes are responsible for certain traits and that the genes are in every cell.•We have used this information and completed the Human Genome project. The mapping out of the human DNA.

Pass it on

•Every organism requires a set of instruction for specifying its traits.

Heredity is the passage of these instructions

(traits) from one generation to another.

Heredity

•The passing of traits from parent to offspring on chromosomes .

•Heredity information is contained in genes, located in the chromosomes of each cell. •Each gene carries a single unit of information. • The different forms of a gene are called alleles.

Alleles•Different forms of a single gene. •One is inherited from each parent and is located on a specific chromosomes• They can be dominant or recessive.

• XX chromosome=Female• XY=Male

•An inherited trait of an individual can be determined by one or by many genes, and a singles gene can influence more than one trait. A human cell contains many thousands of different genes.

Genes•Segments of DNA that carry hereditary instructions and are passed from one parent to offspring; located on the chromosome.

Chromosomes

•They are composed of genes that provide the instruction for making all the proteins in an organism.

•They take on an X Shaped so they can more easily divide among daughter cells.•Chromosomes are directly related to the passing on of traits.

•A cell that has lost its chromosomes will be missing some genes and unable to produce offspring.•Chromosomes control all cell processes

Homologous chromosomes

•Chromosomes that have the same sequence of genes and have the same structure.

• Down syndrome is often called Trisomy 21 because most people with this condition have three copies of the number 21 chromosome. Down syndrome almost always results in mental retardation, though the severity of the retardation varies.

•Have you ever wonder , where did I get this red hair, blue eyes or dark skin color?•Well it is all because of traits.

Traits•An inherited characteristic: a quality or characteristic that is genetically determined.

•Traits can be dominant or recessive.

Dominant Trait

•The trait observed when at least one dominant allele for a characteristic is inherited, and can be seen in every generation of offsping.

•Dominant traits are always represented by a CAPITAL letter!

Recessive Trait

•A trait that is apparent only when two recessive alleles for the same characteristic are inherited and is not seen in every generation of offspring.

•Recessive traits are always represented by a lower case letter!

Human Genome Project

• Completed in 2003, the Human Genome Project (HGP) was a 13-year project coordinated by the U.S. Department of Energy and the National Institutes of Health.

• After mapping out each gene then they begin to look at each chromosome. May of 2006 they were finish with all 26 pairs of chromosomes.

Project goals were to

• identify all the approximately 20,000-25,000 genes in human DNA,

• determine the sequences of the 3 billion chemical base pairs that make up human DNA,

• store this information in databases, • improve tools for data analysis, • transfer related technologies to the private

sector, and • address the ethical, legal, and social issues

(ELSI) that may arise from the project.

What are some practical benefits to learning about DNA?

•Knowledge about the effects of DNA variations among individuals can lead to revolutionary new ways to diagnose, treat, and someday prevent the thousands of disorders that affect us.

Eye Color

• Brown eyes are the most common eye color in the world with over 55% of the world's population having brown eyes. Brown eye color is a dominant genetic trait, and is created by the presence of melanin in the eye.

Diploid

• containing two complete sets of chromosomes, one from each parent. This is the number of chromosomes in a body cell. • Ex: Humans have 46 chromosomes

Haploid

• Half the number of chromosomes. The chromosomes in each sex cell.• Example: In humans, an egg cell

has 23 chromosomes and a sperm cell has 23 chromosomes.