Karyotypes and Gene TechnologyHow we study Genetics

Karyotypes1. 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

Karyotypes4. 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)a. Trisomy 21- Down’s Syndromeb. Increased age during pregnancy increases

risk of Down’s Syndrome

Karyotypes6. 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

Other Methods to Study Genetics

Recombinant DNA used to study OrganismsRestriction EnzymesGenetic EngineeringStem CellsDNA

FingerprintingGenetic modificationsChromosomal analysisElectrophoresis Polymerase chain reactionCloning

Recombinant DNA8. Recombinant (Recombined!) DNA: DNA

made from 2 or more different organismsa. Use DNA/RNA Plasmid (circular DNA) and

insert directly into the vector (Bacteria, virus, fungus etc.)

b. Diabetes:i. Use Human insulin gene, transfer it to a

bacteria.ii. Bacteria can transcribe and translate the

human gene using the same code a human cell does to produce insulin.

Restriction Enzymes10. Restriction Enzyme: an enzyme that cuts DNA molecules at

specific sites

a. Each strand of DNA has a “sticky end” that can be attached to a new piece of complementary DNA

b. This is how recombinant DNA is madec. Enzymes are named after the bacteria they are taken from

(example: EcoRI comes for E. coli)

11. Genetic Engineeringa. Process of manipulating genes for practical purposes.b. Think of your favorite fruits. What would you want to

change to make them even better?o Biggero Sweetero Reddero Juiciero Firmero Resistant to pesticideso More nutritious

i. Genetic engineering is a way to make this happen.

c. Risks? Still highly debated!

12. Stem Cellsa. These cells can turn into virtually ANY type of

human cell.b. Embryonic Stem Cells: from embryos,

undifferentiated, and are immortal. These cells really can become ANYTHING in the human bodyi. Useful for repairing damaged tissuesii. Some risk of tumor development from

contaminated cell culturesiii. Ethical dilemma

12. Stem Cellsb. 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. i. Much harder to find

C. Other Ethical Dilemmas: “Playing God”

12. Stem Cells

12. Stem Cells

13.DNA Fingerprintinga. 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.

b. Unique for every individual (Everyone’s is different)

c. Requires a certain amount of DNA

13. DNA Fingerprintingd. Useful for:

i. Paternity Testsii. Forensic

science- crime investigations

iii. Identifying genetic disorders like Huntington’s diseases and sickle cell anemia

14. Genetic Modificationsa. Genetic Modications:

change in the genetic composition of an organism through genetic engineering

b. Frequently discussed in terms of food, but the same concept is also extended towards animals

c. Not OK to do on people!

15.Chromosomal Analysis

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

16. ElectrophoresisA. Separates DNA Fragments when testing for

specific gene by using an electric fieldDNA 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.

16. Electrophoresis

17. Polymerase Chain Reaction (PCR)

a. Used for small quantities of DNA

b. Copies small select segments of DNA to produce up to a billionfold of DNA material in a matter of hours!

c. Essentially DNA replication in a test tubeUseful for

Solving crimesDiagnosing genetic disordersStudying ancient fragments of DNA found in fossils or in preserved materials

18. Cloninga. A clone is a living copy of an organism.

i. Monozygotic Twins are clones of each otherii. Dolly the Sheep cloned from an adult cell

b. DNA is a complete copy from another cell and is injected into an empty nucleus in a gametic cell.a. Cell division is triggered which can generate

a genetic clone of an organismc. The trouble with clones

a. Very short life spanb. Medical problems: Bad immune system,

fatally oversized, large chance for developmental errors

Cloning