Biotechnology

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Fig. 20-20

Cultured stem cells

Early human embryo at blastocyst stage (mammalian equiva- lent of blastula)

Different culture conditions

Different types of differentiated cells

Blood cells

Nerve cells

Liver cells

Cells generating all embryonic cell types

Adult stem cells

Cells generating some cell types

Embryonic stem cells

From bone marrow in this example

Slide 85

The aim of stem cell research is to supply cells for the repair of damaged or diseased organs

Slide 86

Concept 20.4: The practical applications of DNA technology affect our lives in many ways

Many fields benefit from DNA technology and genetic engineering

Slide 87

Medical Applications

One benefit of DNA technology is identification of human genes in which mutation plays a role in genetic diseases

Slide 88

Diagnosis of Diseases

Scientists can diagnose many human genetic disorders by using PCR and primers corresponding to cloned disease genes, then sequencing the amplified product to look for the disease-causing mutation

Genetic disorders can also be tested for using genetic markers that are linked to the disease-causing allele

Slide 89

Single nucleotide polymorphisms (SNPs) are useful genetic markers

These are single base-pair sites that vary in a population

When a restriction enzyme is added, SNPs result in DNA fragments with different lengths, or restriction fragment length polymorphism (RFLP)

Slide 90

Fig. 20-21

Disease-causing allele

DNA

SNP

Normal allele

T

C

Slide 91

Human Gene Therapy

Gene therapy is the alteration of an afflicted individual’s genes

Gene therapy holds great potential for treating disorders traceable to a single defective gene

Vectors are used for delivery of genes into specific types of cells, for example bone marrow

Gene therapy raises ethical questions, such as whether human germ-line cells should be treated to correct the defect in future generations

Slide 92

Fig. 20-22

Bone marrow

Cloned gene

Bone marrow cell from patient

Insert RNA version of normal allele into retrovirus.

Retrovirus capsid

Viral RNA

Let retrovirus infect bone marrow cells that have been removed from the patient and cultured.