Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download Medical Genetics - s3.amazonaws.com
Document related concepts
no text concepts found
Transcript
Medical Genetics Human Anatomy and Physiology II Oklahoma City Community College Dennis Anderson Mitosis • Produces daughter cells with 46 chromosomes • Used in growth and repair Mitosis • DNA is duplicated • Doubled chromosomes form from duplicated DNA • Each cms has 2 identical chromatids Chromatid Chromatid Mitosis Metaphase Chromosomes line up in a single row. Chromosomes separate Each chromatid becomes a single chromosome Meiosis • Reduce the chromosome number to half that of body cells • Produce gametes – Egg – Sperm Meiosis Metaphase Chromosomes line up in a double row. Chromosomes separate Each each daughter cell gets doubled chromosomes Doubled Chromosomes Separate in Second Meiotic Division Mitosis Metaphase Meiosis Metaphase Double Filed Chromosomes Cms 1 Cms 1 Cms 2 Cms 2 • Daughter cells receive ONE of each cms pair • Daughter cells receive ONE allele for most traits • New combinations of alleles possible Gene • A unit of heredity that controls the development of one trait • Made of DNA Allele • Member of a paired gene – One allele comes from each parent • Represented by a single letter Examples of Alleles Dwarfism = D Normal height = d DD = Dwarfism Dd = Dwarfism dd = Normal height Dwarf Band Dominant & Recessive Alleles • Dominant alleles are expressed • Recessive alleles are not expressed in the presence of a dominant allele – Recessive alleles are only expressed if both recessive alleles are present Homozygous • Both alleles alike • AA or aa Heterozygous • Alleles are different • Aa Genotype • Genetic make up • Represented by alleles • DD & Dd are genotypes for dwarfism Phenotype • A trait • Genotype determines the phenotype • Dwarfism is a phenotype Codominant • • • • Two different alleles are both dominant A = allele for type A blood B = allele for type B blood AB = results in type AB blood Karyotype • Picture of chromosomes from an individual Homologous Chromosomes • Chromosomes of the same pair • Karyotypes are usually arranged with homologous chromosomes paired together Mutation • Change in a gene or chromosome • Causes an abnormal trait Mutagen Agent that causes mutations Cigarette smoke Pesticides X-rays Ulatraviolet light Nuclear radiation Homologous chromosomes line up in a double file in metaphase I of meiosis Homologous Pairs Separate Four Gametes With Single Chromosomes Fertilization Nondisjunction Trisomy Sex Chromosomes Sex Chromosomes • Male have Xy – Male gametes have either X or y • Females have XX – Female gametes have X Autosomes Chromosomes 1-22 X-Linked Traits • Alleles are on the X chromosome • Females have two alleles • Males have one allele – Only one X chromosome Normal Male Normal Female Trisomy 21 Down Syndrome Down Syndrome • • • • Large tongue Flat face Slanted eyes Single crease across palm • Mental retardation – Some are not Maternal Age & Down Syndrome Trisomy 18 Edward Syndrome Edward Syndrome • • • • • • • Heart defects Displaced liver Low-set ears Abnormal hands Severe retardation 98% abort Lifespan < 1 year Trisomy 13 Patau Syndrome Patau Syndrome • Cleft lip and palate • Extra fingers & toes – polydactylism • Defects – Heart – Brain – Kidneys • Most abort • Live span < 1 month Klinefelter Syndrome Klinefelter Syndrome • • • • Breast development Small testes Sterile Low intelligence – Not retarded Klinefelter Website Turner Syndrome Turner Syndrome • Short • Not go through pruberty • Produce little estrogen • Sterile • Extra skin on neck Fetal Testing Sickle Cell Anemia • • • • • • • • RBCs sickle shaped Anemia Pain Stroke Leg ulcers Jaundice Gall stones Spleen, kidneys & lungs Sickle Cell Anemia • Recessive allele, s codes for hemoglobin S – Long rod-like molecules – Stretches RBC into sickle shape • Homozygous recessive, ss have sickle cell anemia • Heterozygous, Ss are carriers Hemophilia Blood clotting impaired Recessive allele, h carried on X cms X-linked recessive trait More common in males Albinism • Lack of pigment – Skin – Hair – Eyes a A Amino Acids Enzyme AA = Normal pigmentation Aa = Normal pigmentation aa = Albino Melanin Pigment PKU Disease • Phenylalanine excess • Mental retardation if untreated Molly’s Story p P Phenylalanine Enzyme PP = Normal Pp = Normal pp = PKU Tyrosine A man & woman are both carriers (heterozygous) for albinism. What is the chance their children will inherit albinism? AA = Normal pigmentation Aa = Normal pigmentation (carrier) Man = Aa Woman = Aa aa = Abino A A a a A a A AA Aa a Aa aa AA Aa Genotypes 1 AA, 2Aa, 1aa Phenotypes Aa aa 3 Normal 1 Albino Probability 25% for albinism A man & woman are both carriers (heterozygous) for PKU disease. What is the chance their children will inherit PKU disease? PP = Normal Pp = Normal (carrier) P p P PP Pp p Pp pp pp = PKU disease PP Pp Genotypes 1 PP, 2Pp, 1pp Phenotypes Pp pp 3 Normal 1 PKU disease Probability 25% for PKU disease A man with sickle cell anemia marries a woman who is a carrier. What is the chance their children will inherit sickle cell anemia? SS = Normal Ss = Normal (carrier) S s s Ss ss s Ss ss ss = Sickle Cell Ss ss Genotypes 2 Ss, 2ss Phenotypes Ss ss 2 Normal (carriers) 2 Sickle cell Probability 50% for Sickle cell A man with heterozygous dwarfism marries a woman who has normal height. What is the chance their children will inherit dwarfism? Dwarfism is dominant. DD = Dwarf Dd = Dwarf dd = Normal d d D Dd Dd d dd dd Dd Dd Genotypes 2 Dd, 2dd Phenotypes dd dd 2 Normal 2 Dwarfs Probability 50% for Dwarfism X-linked Recessive Traits • Alleles are on the X chromosome • Inheritance pattern different in males and females XH XH = Normal Female XH Xh = Normal Female (Carrier) Xh Xh = Hemophilic Female XHy = Normal Male Xhy = Hemophiliac Male A man with hemophilia marries a normal woman who is not a carrier. What is the chance their children will inherit hemophilia? Hemophilia is X-linked recessive. Xh XH = Normal Female XH Xh = Normal Female (Carrier) Xh Xh = Hemophilic Female XHy = Xhy = Normal Male XH X Xh XH Xh XH Xh y XHy XHy Hemophiliac Male H XH Xh XH Xh X H XH Genotypes Xh 2 XH Xh, 2XHy Phenotypes y XHy 2 Carrier Females XHy 2 Normal Males Probability O% for Hemophilia A normal man marries a normal woman who is a carrier for hemophilia. What is the chance their children will inherit hemophilia? Xh XH = Normal Female XH Xh = Normal Female (Carrier) Xh Xh = Hemophilic Female XHy = Xhy = Normal Male XH Xh XH XH XH XH Xh y XHy Hemophiliac Male X hy XH Xh Genotypes XH XH XH XH Xh XH XH , XH Xh, XHy, X hy Phenotypes 2 Normal Females y XHy X hy 1 Normal Males 1 Male Hemophiliac Probability 50% for Male Hemophilic 0% for Female Hemophilic The End
Related documents