Bio 105 Guide 08.

Transcription

1 Bio 105 Guide 08

2 The chromosomes present in 1 cell nucleus!

3 karyotype

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5 Multi Color Chromosome Painting Multi color FISH experiment using four different fluorochromes (DAPI, FITC, Cy3 and Cy5 )

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7 Nondisjunction

8 Common Chromosomal Abnormalities * Turner syndrome results from a single X chromosome (45, X or 45, X0). * Klinefelter syndrome, the most common male chromosomal disease, otherwise known as 47, XXY is caused by an extra X on sex chromosome 23. * Edwards syndrome is caused by trisomy (three copies) of chromosome 18. * Down syndrome, a common chromosomal disease, is caused by trisomy of chromosome 21. * Patau syndrome is caused by trisomy of chromosome 13.

9 Turner syndrome or Ullrich-Turner syndrome encompasses several chromosomal abnormalities, of which monosomy X is the most common. It occurs in 1 out of every 2500 female births.[1] Instead of the normal XX sex chromosomes for a female, only one X chromosome is present and fully functional. A normal female karyotype is labeled 46,XX; individuals with Turner syndrome are 45,X (also labeled 45,X0 or less commonly X(,)) though other genetic variants occur. In Turner syndrome, female sexual characteristics are present but generally underdeveloped.

10 Common Chromosomal Abnormalities Some disorders arise from loss of just a piece of one chromosome, including * Cri du chat (cry of the cat), from a truncated short arm on chromosome 5. The name comes from the babies' distinctive cry, caused by abnormal formation of the larynx.

11 Chromosomal abnormalities can also occur in cancerous cells of an otherwise genetically normal individual; one well-documented example is the Philadelphia chromosome, a translocation mutation commonly associated with chronic myelogenous leukemia and less often with acute lymphoblastic leukemia.

12 Making a Personal Pedigree For each relative, try to write down as many of these items as possible: Age or date of birth (and, for all family members who have passed on, age at death and cause of death). When the information is unavailable, write down your best guess (for example, 40 s ).

13 Cancer Heart disease Gather information on Medical Problems Diabetes Asthma Mental illness High blood pressure Stroke Kidney disease Alcoholism Others

14 Note the ages at which the conditions occurred. Did Uncle Pete have his heart attack at age 42 or age 88? Did your mother develop diabetes in childhood or as an adult? Birth defects such as spina bifida, cleft lip, heart defects, others. Learning problems, mental retardation. Vision loss/hearing loss at a young age (remember to record the age it began).

15 For family members with known medical problems, jot down if they smoked, their diet and exercise habits, and if they were overweight. (for example, you could note that your brother John, who had a heart attack at age 40, weighs 300 lbs and smokes 2 packs a day).

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19 Although all cancer is caused by mutations in specific types of genes (oncogenes, tumor suppressor genes, and DNA repair genes), not all of these mutations are inherited. Only about 1-2% of cancers are hereditary and cluster in families with a strong shared susceptibility. Most people have sporadic cancer without a positive family history of the disease. In the vast majority of cancer cases there is no apparent familial clustering. For most common cancers, an individual with a first-degree relative with the disease will have approximately twice the risk of the general population.

20 PseudoIsochromatic Plate Ishihara Compatible (PIPIC) Color Vision Enter the number you see

21 PseudoIsochromatic Plate Ishihara Compatible (PIPIC) Color Vision Enter the number you see

22 Cystic Fibrosis Carrier Rates Race/Ethnicity Chance of being a carrier Chance both partners are carriers European Caucasian Ashkenazi Jewish 1 in 29 1 in 841 Hispanic American 1 in 46 1 in 2,116 African American 1 in 65 1 in 4,225 Asian American 1 in 90 1 in 8,100

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25 Molecular & Genetic basis of Cystic Fibrosis CF Protein creates a Cl -- permeable channel in the outer cell membrane. Persons with Cystic Fibrosis (OMIM219700) are typically homozygous for an allele with a 3bp deletion (508) that removes a phenylalanine residue from a position near a nucleotide binding domain. CF proteins with this defect are destroyed by the cell. In the absence of Cl -- channels, the Cl / Na balance of the cell is disrupted. This leads to an accumulation of mucous in the lungs, a condition which is can be fatal.

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27 The defect is found in 1 in 20,000 births, a general screening program (PKU Test) has been mandated in many states and is routinely made several days after the birth of an infant. Phenylketonuria (PKU)

28 The End