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The Human Genome The Human Genome Project The Human Genome Project is an ongoing effort to analyze the human DNA sequence. A genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The human genome has over 6 million base pairs. Cont. HGP Completed in 2003 and still being analyzed 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, transfer related technologies to the private sector, and address the ethical, legal, and social issues (ELSI) that may arise from the project. How did they do it? Started w/ DNA Fingerprinting Analysis of sections of DNA that have little or no known function, but vary widely from one individual or another. Gel electrophoresis A closer look……… Karyotypes A picture of chromosomes. We know this is a human karyotype because there are 46 chromosomes. Which 2 chromosomes are the sex chromosomes? The rest are called autosomes. Chromosomal Disorders Get too many or too few copies of a chromosome Caused by non-disjunction during meiosis Examples: Down’s Syndrome: Trisomy 21 Turner’s Syndrome: X_ • Effects 1 in 2500 Females and symptoms include short stature, sterile, "webbed" neck, a low hairline, drooping of the eyelids, differently shaped ears that are set lower on the sides of the head than usual, abnormal bone development (especially the bones of the hands and elbows) Klinefelter’s Syndrome : XXY • Symptoms: Infertility, language and neurological impairment, gynecomastia, lanky, youthful build. Chromosomal Disorders More Examples Patau syndrome-extra 13 • Many don’t survive, but those who do have the following symptoms: mental & motor challenged, polydactyl (extra digits), low-set ears, holoprosencephaly (failure of the forebrain to divide properly), heart defects, structural eye defects, cleft palate, spinal defects, omphalocele (abdominal defect), abnormal genitalia, overlap of fingers over thumb Edward syndrome-extra 18 • Symptoms: Mental retardation, Low set ears, Rocker bottom feet, Flexion deformities on the fingers, Congenital heart disease, Low birth weight, Small lower jaw, Recessed chin, Prominent back of skull The passing on of traits…. In order to ensure that a trait is actually inherited and not the result of environmental influences, you have to study how the trait is passed on from one generation to the next. A pedigree chart, shows the relationship of traits in a family, can be used to help with this task. Pedigree Chart Cleopatra’s Pedigree Russian Royal Family Another special pattern Sex-linked inheritance Many sex-linked genes are found on the X chromosome. More than 100 sex-linked genetic disorders have now been mapped to the X chromosome. Males have just one X chromosome. Thus, all X-linked alleles are expressed in males, even if they are recessive. Colorblind Test Practice Punnett Square Common Examples: Colorblindness Baldness Hemophilia Pedigree showing X vs. Y