Post on 24-Jan-2016
transcript
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
Fig. 12-3, p. 264
Thymine
Adenine
Nucleotide
Cytosine
Phosphate group
Phosphodiester linkage
Guanine
Deoxyribose (sugar)
Fig. 12-5, p. 266
Fig. 12-6b, p. 267
Adenine
Thymine
Deoxyribose
Deoxyribose
Guanine
Cytosine
Deoxyribose
Deoxyribose
http://www.thetech.org/genetics/zoomIn/index.html
Fig. 12-9, p. 270
Fig. 12-9, p. 270
Mutation
Fig. 15-6a, p. 328
Exon
Intron
Exon
Intron
Exon
DNA in a eukaryotic chromosome
Transcription
Pre-mRNA RNA processing (remove
introns)
Mature mRNA
Formation of cDNA relies on RNA processing that occurs in the nucleus to yield mature mRNA.
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
Fig. 16-2, p. 349
I1 2 3 4
II 1 2 3 4 5
III 1 2 3 4
Key: Normal
femaleMating
Normal male Siblings
produced by mating
Albino femaleAlbino male
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
Fig. 16-5d, p. 355
A reciprocal translocation occurs when two non-homologous chromosomes exchange segments.
Fig. 16-3, p. 352
Fig. 16-3a, 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. 16-3b, p. 352
Nondisjunction of X in second meiotic division
Nondisjunction of Y in second meiotic division
Normal first meiotic division
XX X
XXY
Y
Y YY
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. 16-5b, p. 355
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. 16-5c, 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. 16-6, 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
1 μm
Fragile site
CGG repeats (200 to more than 1000 times)
CGG repeats (up to 50 times)
Fig. 16-7, p. 357
Fig. 16-9, p. 359
Fig. 16-11, p. 361
Fig. 16-11, p. 361
About 20 mL of amniotic fluid containing cells sloughed off from fetus is removed through mother's abdomen.
16-week fetus
Ultrasound probe determines position of fetus
Uterine wall
Amniotic cavity
Fluid is centrifuged.
Amniotic fluid is analyzed.
Placenta Fetal cells are checked to determine sex, and purified DNA is analyzed.
Some cells are grown for 2 weeks in culture medium.
Karyotype is analyzed for sex chromosomes or any chromosome abnormality.
Cells are analyzed biochemically for presence of about 40 metabolic disorders.
1
2
3
4
5
7
6
Fig. 16-12, p. 362
Fig. 16-12, p. 362
Transabdominal sampling technique
Withdrawn chorionic villi cells
Cervical sampling techniqueUltrasound
probe
Catheter
SyringeWithdrawn
chorionic villi cells o
r
Chorionic villi
Cells are cultured; biochemical tests and karyotyping are performed
Catheter
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