Karyotypes and Gene Technology

1. Karyotypes and Gene Technology How we study Genetics

2. Karyotypes 1. Karyotypes: a photo of the chromosomes in a dividing cell that shows chromosomes arranged by size. 2. Every person needs 46 chromosomes for normal development and function. 3. Written in pairs of chromosomes (1-22), the last of which are the Sex Chromosomes

3. Karyotypes 4. Too many chromosomes or too few can cause serious problems a. May cause extremely short life span 5. Trisomy (more than one copy of a chromosome) • Trisomy 21- Down’s Syndrome • Increased age during pregnancy increases risk of Down’s Syndrome

4. Karyotypes 6. Disjunction: when chromosomes of each homologue separate during meiosis 7. If chromosomes don’t separate correctly, we call this a Non-Disjunction a. One gamete gets an extra chromosome  Down’s Syndrome

5. Other Methods to Study Genetics • Recombinant DNA used to study Organisms • Restriction Enzymes • Genetic Engineering • Stem Cells • DNA Fingerprinting • Genetic modifications • Chromosomal analysis • Electrophoresis • Polymerase chain reaction • Cloning

6. Recombinant DNA 8. Recombinant (Recombined!) DNA: DNA made from 2 or more different organisms a. Use DNA/RNA Plasmid (circular DNA) and insert directly into the vector (Bacteria, virus, fungus etc.) b. Diabetes: • Use Human insulin gene, transfer it to a bacteria. • Bacteria can transcribe and translate the human gene using the same code a human cell does to produce insulin.

7. Restriction Enzymes 10. Restriction Enzyme: an enzyme that cuts DNA molecules at specific sites • Each strand of DNA has a “sticky end” that can be attached to a new piece of complementary DNA • This is how recombinant DNA is made • Enzymes are named after the bacteria they are taken from (example: EcoRI comes for E. coli)

8. 11. Genetic Engineering • Process of manipulating genes for practical purposes. • Think of your favorite fruits. What would you want to change to make them even better? • Bigger • Sweeter • Redder • Juicier • Firmer • Resistant to pesticides • More nutritious • Genetic engineering is a way to make this happen. • Risks? Still highly debated!

9. 12. Stem Cells • These cells can turn into virtually ANY type of human cell. • Embryonic Stem Cells: from embryos, undifferentiated, and are immortal. These cells really can become ANYTHING in the human body • Useful for repairing damaged tissues • Some risk of tumor development from contaminated cell cultures • Ethical dilemma

10. 12. Stem Cells b. Adult Stem Cells: come from bone marrow or the adult brain. These cells are not as versatile as embryonic stem cells and are not immortal. • Much harder to find C. Other Ethical Dilemmas: “Playing God”

11. 12. Stem Cells

12. 12. Stem Cells

13. 13.DNA Fingerprinting • Pattern of dark bands on a photographic film that’s made when an individual’s DNA restriction fragments are separated by gel electrophoresis, probed and exposed to an X-ray film. • Unique for every individual (Everyone’s is different) • Requires a certain amount of DNA

14. 13. DNA Fingerprinting d. Useful for: • Paternity Tests • Forensic science- crime investigations • Identifying genetic disorders like Huntington’s diseases and sickle cell anemia

15. 14. Genetic Modifications • Genetic Modications: change in the genetic composition of an organism through genetic engineering • Frequently discussed in terms of food, but the same concept is also extended towards animals • Not OK to do on people!

16. 15.Chromosomal Analysis A. Study of the number and structure of all 46 chromosomes (also called Karyotypes) • Highly accurate • Analyzes 15-20 cells to determine whether all or just some cells have normal chromosomes • Geneticists look for thinks like leukemia to determine the best treatment options, down’s syndrome, missing sex chromosomes, risk of miscarriages

17. 16. Electrophoresis A. Separates DNA Fragments when testing for specific gene by using an electric field • DNA molecules are separated by size on a rectangular gel. • Smaller fragments move faster and farther, forming a pattern of bands • Specific genes are isolated from these bands by transferring the fragments in the gel to a filter paper and binding them to a “probe” that may glow when bound to a gene of interest.

18. 16. Electrophoresis

19. 17. Polymerase Chain Reaction (PCR) • Used for small quantities of DNA • Copies small select segments of DNA to produce up to a billionfold of DNA material in a matter of hours! • Essentially DNA replication in a test tube • Useful for • Solving crimes • Diagnosing genetic disorders • Studying ancient fragments of DNA found in fossils or in preserved materials

20. 18. Cloning • A clone is a living copy of an organism. • Monozygotic Twins are clones of each other • Dolly the Sheep cloned from an adult cell • DNA is a complete copy from another cell and is injected into an empty nucleus in a gametic cell. • Cell division is triggered which can generate a genetic clone of an organism • The trouble with clones • Very short life span • Medical problems: Bad immune system, fatally oversized, large chance for developmental errors

21. Cloning