Cell Biology: DNA

1. Cell Biology:DNA Lesson 2 – Recombinant DNA (Inquiry into Life pg. 500-507)

2. Today’s Objectives • Describe Recombinant DNA, including: • Define recombinant DNA • Describe a minimum of 3 uses for recombinant DNA

3. Recombinant DNA • Definition: • DNA having genes from 2 different organisms, often produced in the laboratory by introducing foreign genes into a bacterial plasmid • A vector is used to introduce recombinant DNA into a cell • A plasmid is the most common vector • They are small rings of DNA found in bacteria • The plasmid has to be removed from the bacteria and has to have a foreign gene inserted into it

4. Insertion of Foreign Genes • An enzyme (restriction enzyme) breaks the plasmid DNA ring • The new foreign DNA can now be attached to the plasmid • The enzyme ligase acts like glue which sticks the foreign DNA to the plasmid and recreates the ring

5. Insertion of Foreign Genes

6. Recombinant DNA • The plasmid DNA is then put back into the bacteria • This bacteria will now replicate every cell the same as the one just put in • Eventually there are many copies of the foreign gene

7. Applications of Recombinant DNA • Recombinant human insulin • Human insulin gene inserted into bacteria E. Coli, used to treat diabetes • Recombinant human growth hormone (HGH) • Treats patients with pituitary gland deficiencies to support normal growth and development • Inserted into livestock to produce larger specimens • Recombinant blood clotting factor VIII • Blood clotting protein administered to patients with bleeding disorders • Recombinant hepatitis B vaccine • Control of hepatitis B virus • Diagnosis of HIV infection • Methods for diagnosing HIV have been developed using recombinant DNA • Herbicide and Insect resistant crops • Used in agriculture to reproduce genes that help crops resist attack by insects and protect crops from herbicides

8. Applications of Recombinant DNA • Generate DNA libraries which will catalogue all the base sequences of known genes • Identify specific genes • In 1998, the gene that mutates to cause prostate cancer was identified • Produce synthetic copies of genes • Insert genetic material into chromosomes that will help regulate cell function to make organisms genetically “better”

9. Viral DNA • Viral DNA (DNA from a virus) can also be used as a vector to carry recombinant DNA into a cell • When a virus containing recombinant DNA infects a cell, the viral DNA enters • Here it can direct the reproduction of many more viruses • Each virus derived from a viral vector contains a copy of the foreign gene, therefore viral vectors allow cloning of a particular gene

10. Viral Vectors • Viral vectors are also used to create genomic libraries • A genomic library, or gene bank, is a collection of engineered viruses that carry all the genes of a species • Purpose: • Break up DNA into manageable chunks for research • Can analyze specific strands of DNA/amino acid sequences to determine their function, which can then be inserted into other cells • Stores all of the DNA for a species • It takes about 10 million viruses to carry all the genes of a mouse

11. Summary • Segments of DNA (particular genes) can be inserted into bacteria and the bacteria will produce these genes • If desired genes are used – like those that produce certain chemicals (vaccines, antibodies, etc.) then these proteins become much more available • Protein hormones like insulin (regulates blood-sugar levels) can be made using yeast cells • Interferon, a protein used in cancer treatments to help the immune system is now mass-produced in this way

12. Antibiotic Resistance • More and more bacteria are becoming resistant to our common antibiotics, and to make matters worse, more and more are becoming resistant to all known antibiotics • The problem is known as multi-resistance, and is generally described as one of the most significant future threats to public health • Antibiotic resistance can arise in bacteria in our environment and in our bodies • Antibiotic resistance can then be transferred to the bacteria that cause human diseases, even if the bacteria are not related to each other

13. Antibiotic Resistance • Antibiotic resistance-carrying plasmids from different bacteria can meet and exchange genetic material • The result is plasmids consisting of genes that have each been adapted to different bacterial species

14. Antibiotic Resistance • This facilitates further adaptation and mobility, and consequently the spread of antibiotic resistance between different bacterial species

15. Antibiotic Resistance • Widespread abuse of antibiotics, particularly in agriculture, is rapidly increasing the proliferation of multi-resistant bacteria

16. Antibiotic Resistance • Left unchecked, multi-resistant bacteria represent one of the greatest future health concerns in the world and could see the return of previously controlled diseases that affected humans in the past…… • WITHOUT THE ABILITY TO STOP THEM • Currently, bacteria are developing multi-resistance faster than scientists can develop new antibiotics to control them

17. Are you scared yet?!