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