Transcript Chromosome
1 Chromosome telomere p arm centromere q arm telomere http://www.sciencenetlinks.com/interactives/dna.swf 2 A Metaphase Spread •Seen under a microscope •From cells grown in lab and arrested in metaphase •Photographed •In past, cut and paste manually •Today, computerized http://www.mwit.ac.th/~bio/assets/karyotype_mutation.swf 3 4 http://www.youtube.com/watch?v=yoxMGHNj3ZU http://www.youtube.com/watch?v=E0WkZr819UU http://www.youtube.com/watch?v=RTo2lRgfluI 5 Karyotype • Definition: Organization of Chromosomes from a metaphase spread • Chromosomes organized by: 1. Size of Chromosomes 2. Centromere location 3. Banding pattern 6 7 8 Autosomes First 22 pairs of chromosomes Sex Chromosomes 23rd pair of chromosomes X and Y 9 Gene Map Diagram that indicates the location of genes on a chromosome. Locus A gene’s address on a chromosome. Example 2p3,32 10 http://www.dnalc.org/ddnalc/resources/chr11a.html 11 Rh- Rh- Rh+ Rh+ Rh- Rh+ 12 EE ee Ee 13 NN nn Nn 14 HH hh Hh 15 AA aa Aa 16 CC cc Cc 17 AA BB OO AB AO BO 18 GG gg Gg 19 SS S’S’ SS’ 20 SS ss Ss 21 PP pp Pp 22 AA aa Aa 23 BB bb Bb 24 TT tt Tt 25 CC cc Cc 26 MM mm Mm 27 DD dd Dd 28 FF ff Ff 29 Xcb or XN Xcb Xcb Xcb Y XN X N XN Xcb XN Y 30 XH or Xh X H XH Xh X h (alleles) XH Xh 31 XN or Xdmd XN X N Xdmd Xdmd (alleles) XN Xdmd 32 tdf (alleles) Ytdf 33 Rh Factor •A protein found on red blood cells •If an individual has it + •If an individual does not have it - Have + blood if you gave yourself at least one Rh+ allele. 34 Ehler-Danlos •Fragile, Hyperextensibility of Joints & Skin •Collagen disorder •Autosomal Dominant •Have if carry at least one “E” 35 Acne (fictional) •Combine with gene on chromosome 6 •POLYGENIC • NNNN = severe acne NNNn = moderate acne NNnn = mild acne Nnnn = very mild acne nnnn = no acne 36 Huntington’s Chorea •Mid-life, neurological decline •“Chorea”: jerky, dance-like movements •Gene’s location discovered by Nancy Wexler whose mother had the condition •Leads to many bioethical considerations. •Would you be tested? Have if you gave yourself a “H”. 37 Albinism Frequency: 1/37,000 white, 1/15,000 black, 1/20 Indians Symptoms: lack color in skin and eyes Have if you gave yourself two “a”s. 38 Cystic Fibrosis Frequency: 1/20 are carriers; 1/1600 have the condition Symptoms: Pulmonary infections, intestinal obstructions, salty sweat; ave. lifespan ~30 years 39 Percussion & Antibiotic Treatments Have if you gave yourself “cc”. 40 Blood Types 1. 3 alleles – A, B & O 2. AA, AO = Type A BB, BO = Type B AB = Type AB OO = Type O 3. codominance: A & B can be expressed together 4. A & B are dominant to O 41 Galactosemia Description: Inability to breakdown galactose Misc: Treat with galactose-free diet Frequency: 1/57,000 Symptoms: GI problems retardation Have if you gave yourself “gg”. 42 Index Finger Length SS Short Short SS’ Long Short S’S’ Long Long 43 Sickle Cell Anemia Description: abnormal hemoglobin; RBCs sickle 44 Sickle Cell Anemia Normal Hemoglobin Abnormal Hemoglobin Thus, hemoglobin cannot do its job of carrying oxygen. Symptoms: Tire easily anemic; heart failure, stroke and pain due to blockage of blood vessels. Have if gave yourself “ss”. 45 Phenylketonuria Description: Phenylalanine not converted to tyrosine; builds in brain Mental retardation if untreated Have if gave yourself “pp”. 46 Tallness Chromosomes 13, 14, 16 & 18 8 capital letters 7’ 4” 7 capital letters 7’ 0” 6 capital letters 6’ 8” 5 capital letters 6’ 4” 4 capital letters 6’ 0” 3 capital letters 5’ 8” 2 capital letters 5’ 4” 1 capital letters 5’ 0” 0 capital letters 4’ 8” polygenic 47 Tay-Sachs Symptoms: at 6 mo. regression death Description: lipid enzyme missing; buildup of lipids in the brain Lysosomes of brain swollen with lipids. Have if gave yourself “tt”. 48 Marfan Syndrome Description: Defective fibrillin Protein found in Connective tissue Symptoms: Tall, thin, long Limbs, nearsighted, Aortic aneurism Have if gave yourself at least 1 “M”. 49 Familial Hypercholesterolemia Description: Lack LDL receptors in the liver Symptoms: high cholesterol 500-800 (180 is normal); heart attacks; cholesterol deposits under skin Misc: recall Stormy Jones Have if you gave yourself at least 1 “F”. 50 Colorblindness Females have to have 2 Xcb; Males need to have just 1 Xcb. 51 Hemophilia: "Bleeder's disease" increased time required to form clots Factor VIII Ryan White From Kokomo, Indiana Females have to have 2 Xh; Males need to have just 1 Xh. 52 Muscular Dystrophy muscle weakness due to wasting away of tissue Dystrophin molecule Posture progression a. onset 1-6 years old b. 3/10,000 males c. wheelchair by age 12 d. die by age 20 of respiratory or cardiac failure Females have to have 2 Xdmd; Males need to have just 1 Xdmd. 53 Testis Determining Factor 54 ------ short, webbed neck crude sexual development wide chest no ovarian development no mental retardation Turner’s Syndrome 55 Down Syndrome (47 +21) 56 Pateau Syndrome (47 +13) 57 Edwards Syndrome (47 + 18) 58 General Genetics Terms Genome All the genes of a an organism. Human Genome Project 1. Began in 1990 2. Funded by Nat;l Institute of Health & US Dept. of Energy 3. Cost: $3 Billion 4. Why? Develop tests and treatment for every genetic disease at the DNA level. Not just treat the symptoms. 59 DNA •Deoxyribonucleic Acid •Large, genetic information-holding molecule •Sections which code for a specific protein are genes •Polymer (repeating unit molecule) which winds around proteins to create chromosomes 60 Chromosome •A unit of DNA wrapped around histone proteins •46 found in humans 61 Homologous •Contain DNA that codes for the same traits •Both chromosomes with same genes at the same location. •However each location may have different forms of the gene (alleles). 62 allele B •Definition: various forms of a trait b •Examples: blue vs. brown eyes normal vs. Tay-Sachs A, B & O blood types B z 63 homozygous T T Definition: having identical forms of an allele for a trait heterozygous B b Definition: having different forms of an allele for a trait Gene 1 is homozygous for TT Gene 2 is heterozygous for Bb 64 Genotype Definition: the genetic make-up or alleles carried by a gene pair. Phenotype Definition: the expressed or visible trait due to a gene pair. 65 Maternal Paternal Pertaining to the mother Pertaining to the father 66 Dominant Recessive In a heterozygous situation, the gene that is seen. In a heterozygous situation, the gene that is hidden. Condition that requires only one Mutated allele for symptoms to Show. Condition that requires two mutated alleles for symptoms to Show. 67 Pedigree A Family Tree 68 Polygenic Traits to which more than one gene contribute Most traits are polygenic, especially those that show a range of variation (i.e.. Height, hair color, skin color, eye color, etc.) VS. Pleitropy: 1 gene causes many symptoms 69 1° 2° 3° Relatives 1° Relative 2° Relative Persons with whom you share ½ of your chromosomes Persons with whom you Share ¼ of your chromosomes Parents, siblings Grandparents, aunts, uncles 3° Relative Persons with whom you share 1/8 of your chromosomes Great-grandparents Great-aunts & uncles cousins 70 Autosomal Recessive A condition whose gene is located on one of the first 22 pairs of chromosomes And Presents itself only when both chromosomes carry the abnormal allele (i.e. tt) Tends to skip generations Examples: Cystic Fibrosis, Tay-Sachs Tends to affect ¼ of the population Can be inherited from unaffected parents Tt x Tt tt 71 Autosomal Dominant A condition whose gene is located on one of the first 22 pairs of chromosomes And Presents itself when only one of the mutated alleles is present (i.e.. Tt or TT) Found in each generation Examples: Marfan’s, Huntington’s Tends to affect 3/4 of the population Affected parents may have an unaffected child Tt x Tt tt 72 Sex-Linked A condition whose gene is found on the 23rd pair of chromosomes Tends to occur more in males Examples: Muscular Dystrophy, Color blindness 73 Population Genetics Gene Frequency Carrier Frequency In a population, the rate of occurrence for a given allele In a population, the rate of occurrence for heterozygous individuals Example for “Hand shape” trait: 15 fists 30 hands = Example for “Hand shape” trait: 8hand/fists 15 people = 50% ~50% VS. 74 Breast Cancer Assessment Ana’s Profile Characteristic Risk ↑ or ↓ or ↔ Age ↑ Pregnancy Age ↓ Menopause Age ↑ Hormone Replacement ↑ Weight Gain ↑ Familial History ↑ 75 Paula’s Profile Characteristic Risk ↑ or ↓ or ↔ Age ↑ Personal Cancer History ↑ Familial History ↑ Familial Genetic Testing ↑ Niece ↔ Personal Genetic Testing ↑ Daughter ↔ 76 Nora’s Profile Characteristic Risk ↑ or ↓ or ↔ Age ↔ Menarche ↔ Pregnancy History ↑ Oral Contraceptive ↔ Hormone Replacement ↓ Smoking ↔ Alcohol Consumption ↔ Familial History ↑ Ethnicity ↑ 77 June’s Profile Characteristic Risk ↑ or ↓ or ↔ Age ↔ Mammograms ↔ Menarche ↔ Pregnancy History ↔ Menopause ↓ Hormone Replacement ↓ Blood Pressure Cholesterol ↔ Thyroid Hormone ↔ Osteoporosis ↔ Familial History ↔ 78 Patient Ana Paula Nora June Rank Recommendations 3 Consider stopping HRT, lose weight, regular mammograms 1 Current tumor high priority, BRCA testing for niece & daughter 2 Continue mammograms, consider gene testing 4 Mammogram once a year; exercise & diet 79