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Unidad de Genética Humana ADN (DNA) : Es el Material de Herencia de los Organismos. Es la molécula de ácido desoxirribonucleíco Estructura del DNA : Modelo propuesto por Watson, Crick y Wilkins. (1953). Consiste de una hélice doble de Nucleótidos. Fig. 16-1b, p. 348 Cromosomas Composición del DNA Composición del Nucleótido: Azúcar desoxiribosa 4 Bases Nitrogenadas: Purinas: Adenina (A) y Guanina (G) Pirimidinas: Citosina (C) y Timina (T) Grupos fosfatos ( PO4) Table 12-1, p. 263 Fig. 12-3, p. 264 Thymine Adenine Nucleotide Cytosine Phosphate group Guanine Phosphodiester linkage Deoxyribose (sugar) Fig. 12-3, p. 264 Fig. 12-5, p. 266 Adenine Thymine Deoxyribose Guanine Deoxyribose Deoxyribose Cytosine Deoxyribose Fig. 12-6b, p. 267 http://www.thetech.org/genet ics/zoomIn/index.html Fig. 12-9, p. 270 Mutation Fig. 12-9, p. 270 Exon Intron DNA in a eukaryotic chromosome Pre-mRNA Exon Intron Exon Transcription RNA processing (remove introns) Mature mRNA Formation of cDNA relies on RNA processing that occurs in the nucleus to yield mature mRNA. Fig. 15-6a, p. 328 DNA Representa el material de herencia Está localizado dentro del núcleo en los cromosomas. Tenemos 22 pares llamados autosomales 1-22 El #23 es el cromosoma sexual: XX y XY En la molécula del DNA hay secuencias de genes Los genes Codifican para proteínas. DNA RNA mensajero proteínas Relación de DNA y proteínas El DNA se transcribe a m RNA = Transcripción Si el mRNA se traduce a una proteína= Traducción When genes go bad: Mutations & diseases http://www.thetech.org/genetics/art04_bad. php Métodos usados por los geneticistas para estudiar patrones de Herencia. Árbol genealógico Cariotipos Ánálisis bioquímico o Metabólico Genética al Reverso ( Genética Molecular) Árbol genealógicos Pedigree: representación de los miembros de un tronco familiar a través de diferentes generaciones. Véase símbolos y modelos Fig. 16-2, p. 349 I 2 1 3 4 4 5 II 1 2 3 III 1 2 3 4 Key: Normal female Mating Normal male Albino female Albino male Siblings produced by mating Fig. 16-2, p. 349 p. 366 Herencia Genes autosomales: dominantes AA, Aa recesivos aa Herencia ligada al sexo Al cromosoma XX Al cromosoma XY Estudio de Cruces Albinismo autosomal recesivo Hungtinton autosomal dominante Tay Sachs autosomal recesivo Hemofilia ligado al sexo: cromosoma X gen recesivo Daltonismo ligado al sexo gen recesivo Grupos sanguíneos: Alelos múltiples Grupo A Grupo B Grupo AB Grupo O Genes dominantes: A y B Genes Recesivos: O Cariotipos Mapa de los cromosomas de un individuo. En humanos, 46 cromosomas. 23 los porta el gameto femenino (Óvulo) 23 los porta el gameto masculino ( Espermatozoide) Ambos gametos son haploides= poseen la ½ del total de cromosomas. Anomalías Cromosómicas Delección: Cromosoma #5 Cri-du chat Cromosomas extras): Cromosoma sexual X O en .. Ejs. hombres Klinefelter XXY Síndrome de Down Trisomía en el par # 21 Otras anomalías Ausencia de un cromosoma : mujer Turner XO Le falta un cromosoma sexual Traslocación: fragmentos de un cromosoma se desprende y se inserta en otro grupo Ej. Síndrome de Down Fig. 16-1, p. 348 Fig. 16-1a, p. 348 Fig. 16-1b, p. 348 Fig. 16-4, p. 353 A reciprocal translocation occurs when two non-homologous chromosomes exchange segments. Fig. 16-5d, p. 355 Fig. 16-3, p. 352 Nondisjunction in first meiotic division XY XY X Y First meiotic division nondisjunction results in two XY sperm and two sperm with neither an X nor a Y. Fig. 16-3a, p. 352 Normal first meiotic division Nondisjunction of X in second meiotic division XX Nondisjunction of Y in second meiotic division X X X Y Y YY Y Second meiotic division nondisjunction of the X chromosome results in one sperm with two X chromosomes, two with one Y each, and one with no sex chromosomes. Nondisjunction of the Y chromosome results in one sperm with two Y chromosomes, two with one X each, and one with no sex chromosome (box on right). Fig. 16-3b, p. 352 An inversion is a chromosome segment with a reversed orientation. An inversion does not change the amount of genetic material in the chromosome, only its arrangement. Fig. 16-5b, p. 355 Lost segment A deletion is the loss of a chromosome segment. A deletion can occur at the tip (shown) or within the chromosome. Fig. 16-5c, p. 355 1 μm Fragile site CGG repeats (200 to more than 1000 times) CGG repeats (up to 50 times) Fig. 16-6, p. 356 1 μm Fragile site CGG repeats (200 to more than 1000 times) CGG repeats (up to 50 times) Fig. 16-6, p. 356 Fig. 16-7, p. 357 Fig. 16-9, p. 359 Fig. 16-11, p. 361 16-week fetus Ultrasound probe determines position of fetus Uterine wall 1 About 20 mL of amniotic fluid containing cells sloughed off from fetus is removed through mother's abdomen. Amniotic cavity 2 Fluid is centrifuged. 3 Amniotic fluid is analyzed. Placenta 6 Karyotype is analyzed for sex chromosomes or any chromosome abnormality. 5 Some cells are grown for 2 weeks in culture medium. 4 Fetal cells are checked to determine sex, and purified DNA is analyzed. 7 Cells are analyzed biochemically for presence of about 40 metabolic disorders. Fig. 16-11, p. 361 Fig. 16-12, p. 362 Transabdominal sampling technique Withdrawn chorionic villi cells Ultrasound probe Catheter Cervical sampling technique Syringe Withdrawn chorionic villi cells or Chorionic villi Catheter Cells are cultured; biochemical tests and karyotyping are performed Fig. 16-12, p. 362 Análisis metabólicos o bioquímicos Heredados adquiridos Desórdenes Tay Sachs: deficiencia de la enzima Hexosaminidasa A Diabetes: deficiencia de insulina Fenilcetonuria: bebés no pueden procesar la fenilalanina. Niveles elevados lesionan el cerebro y causan retraso mental y se diagnostican PKU+ Otros trastornos Amiloidosis: acumulación y depósito de proteínas anormales en órganos. Deterioro de órganos Genética al Reverso A nivel molecular Identifica genes en los cromosomas Secuenciación del genoma.. conocer la secuencia de las millones de bases nitrogenadas en nuestro genoma The Human Genome Project Findings Human genome contains ~25,000 genes New genes, including many disease-associated genes have been discovered Has determined the nucleotide sequence of all the DNA in our entire set of genes, called the human genome The genes comprise 2% of all the DNA Plasmids Cutting DNA with a restriction enzyme Information flow from DNA to protein Transcription RNA molecule complementary to the template DNA strand synthesized Translation Polypeptide chain specified by messenger RNA (mRNA) is synthesized Gene therapy Normal allele is cloned DNA introduced into certain body cells One technical challenge is finding appropriate vector Recombinant DNA methods Restriction enzymes Enzymes from bacteria Used to cut DNA molecules in specific places Enable researchers to cut DNA into manageable segments Vector molecule carrier of DNA fragment into cell Transformation: uptake of foreign DNA into cells Producing a genomic or chromosome library Chain termination method of DNA sequencing DNA sequencing Based on chain termination method Yields information about Structure of gene Probable amino acid sequences of its encoded proteins Applications of DNA technology Gene therapy Tissue engineering DNA typing GM Plants and Medicines Medically useful genes can be inserted into plants—example: Plants could be engineered to produce human antibodies, conferring passive immunity to microbial infection merely by eating the plant Section 13.3 Outline 13.3 Biotechnology in Forensics How Biotechnology Revolutionized Forensics Amplification of DNA by Polymerase Chain Reaction Gel Electrophoresis: Separation of DNA Fragments DNA Probes Are Used to Highlight Bands in a Gel DNA Fingerprinting Section 13.6 Outline 13.6 Biotechnology in Medicine DNA Technology Can Be Used to Diagnose Inherited Disorders Restriction Enzyme Fragment Analysis Identification of Defective Alleles with DNA Probes DNA Technology Can Be Used to Treat Disease