1. Relationship between Genotype and Phenotype
Molecular Basis for
Relationship between Genotype and Phenotype
genotype
DNA
DNA sequence
transcription
RNA
translation
amino acid
sequence
protein
function
phenotype
organism

2. ~ 25,000 genes in humans are potential candidates for gene therapy.

3. Molecular Genetic Diagnostics: Sickle Cell Anemia
Electron Micrograph
HbA codes for normal b-globin and produces normal hemoglobin.
HbS produces sickled red blood cells.
Homozygotes for HbS are anemic.
HbS produces b-globin that differs from normal protein by one amino acid.

4. Molecular Genetic Diagnostics: Sickle Cell Anemia

5. Molecular Genetic Diagnostics: Sickle Cell Anemia

6. Methods of introducing a transgene
Solution of DNA to be studied is injected into host cell.
Recombinant DNA can be delivered into host cell using a viral vector.
Refer to Figure 10-22(a), Griffiths et al., 2015.

7. Methods of introducing a transgene
Bombardment with DNA-coated tungsten particles introduces DNA into host cell.
Under favorable conditions, DNA can be taken up by host cell by transformation.
Refer to Figure 10-22(b), Griffiths et al., 2015.

8. Relationship between Genotype and Phenotype
Molecular Basis for
Relationship between Genotype and Phenotype
genotype
DNA
DNA sequence
transcription
RNA
translation
amino acid
sequence
protein
function
phenotype
organism

9. Transgenesis
Introduction of foreign genetic material into a host organism.
2. Ability of the new genetic material to be
transmitted to offspring of the host.
3. Potential of the new genetic material to
be expressed in the host.
4. Transgenic animals or transgenic plants
are the result of this process.

10. Ti (tumor-inducing) plasmid is 200-kb double-stranded circular DNA.
Agrobacterium tumefaciens (soil bacterium) causes crown gall disease in infected plants.
Ti (tumor-inducing) plasmid is 200-kb double-stranded circular DNA.
T-DNA region is transferred and randomly inserted into host plant genome.
T-DNA directs tumor production and synthesis of opines, compounds that the bacterium needs for growth.

11. Genetic Engineering in Plants using Ti Plasmid
T-DNA can be replaced by DNA sequence of interest and introduced into host plant genome.
Reporter genes (selectable markers) are spliced into the recombinant T-DNA.
Successful integration is indicated by expression of reporter genes.
Refer to Figure 10-24, Griffiths et al., 2015.
Markers (reporter genes) such as kanamycin resistance gene are very useful in monitoring successful transformation.

12. Generation of a Transgenic Plant
Refer to Figure 10-25, Griffiths et al., 2015.

13. Genetic Engineering in Plants
Plants that have been transformed include horse-radish, morning glory, cucumber, carrot, yam, cotton, sunflower, lettuce, tomato, corn, soybean, alfalfa, tobacco, potato, and clover.
Agriculturally important crops can be engineered to express:
- viral resistance
- pesticide resistance
- herbicide resistance
- insect resistance
Nutritional value can be enhanced, for example, by introduction of genes that increase seed protein content.
Plants can be engineered to produce pharmaceutically important proteins or vaccines.
Luciferase gene is useful as a reporter gene for transformation.