Download Unidad de Genética Humana

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