Biotechnology

Question 1

What are restriction enzymes?

Answer 1

Restriction endonucleases recognize and cut specific palindromic base sequences

Break hydrogen bonds between bases then covalent bonds in phosphate-sugar backbone

Found in virus resisting bacteria (enzymes cleave foreign DNA to prevent reproduction)

Methyl group labels on bacteria DNA prevent cleaving

Sticky / staggered ends aren’t straight, blunt ends are

Question 2

What is PCR and its process?

Answer 2

Polymerase Chain Reaction makes many copies of DNA from a small amount
Used in Covid test, forensic investigations
Time consuming

1) get a sample of evidence DNA
2) place in test tube with TAQ (thermos aquaticus bacterial enzyme from Yellowstone hot spring) and free nucleotides
3) heat to 95°C (all other proteins denatured but TAQ fine because of hot spring)
4) polymerases split DNA from 1 piece to 2
5) cool test tube for DNA to form
6) repeat 28 times to amplify to 1 million pieces of DNA
7) use for testing

Question 3

What is the DNA fingerprinting process?

Answer 3

1) treat amplified DNA from crime scene and suspects with the same restriction enzyme
2) micropipette DNA into wells in an agar gel, expose to electric field
3) DNA has a negative charge in the phosphate group
4) DNA strands pulled toward positive end (smaller strand with fewer bases travels further)
5) DNA must have the same number of pieces at the same distance to be a match

Use DNA ladder with known base quantities to estimate other sizes

Question 4

What is genetic engineering / GMOs?

Answer 4

Genes are transferred between species, works because the genetic code is universal

1) treat bacterial plasmid and human DNA with the same restriction enzyme
2) mix DNAs and add DNA ligase to splice together
3) recombinant DNA inserted back to host cell (bacteria)
4) bacteria rapidly reproduces and creates desirable gene via binary fission and protein synthesis

Using the restriction enzyme, gene can be inserted into the genome of a different species
ex: arctic fish donor and tomato host → frost resistant tomatoes, soil bacteria donor and corn host → pesticide corn

Question 5

What is cloning?

Answer 5

Clones are groups of organisms with identical genotypes (identical twin) or descended from 1 parent cell

Embryo method: early embryo split into 2-4-8 cells when pluripotent transferred to surrogate, results in 8 clones

Dolly method: donor udder cell donates nucleus to unfertilized egg cell without nucleus, 2n cell put into foster mother to divide normally, results in cloned baby from udder cell donor

Question 6

What is reproductive cloning? therapeutic cloning?

Answer 6

Reproductive cloning clones a whole organism
Clones send to die young because their telomere caps are worn down at birth

Therapeutic cloning clones tissue from stem cells

Question 7

What is stem cell therapy?

Answer 7

Stem cells retain their capacity to divide and differentiate along different paths
From embryos (best), umbilical cords, adult tissue (worst)

Cells cultured and exposed to chemical signals → differentiation
Make tissue or treat disease
1) Stragardt’s muscular dystrophy (recessive mutation in kids causes sight deterioration or blindness)
2) Leukemia cancer of white blood cells from bone marrow (large needle removes fluid in marrow, stem cells removed from fluid, chemo kills cancer, stem cells go back to reestablish and make blood)

Question 8

What was the Human Genome Project?

Answer 8

Genome is the total genetic material in an organelle, cell, or organism

HGP was a cooperative international venture that sequenced an entire human genome in 2003

Now tech is used for multiple species to identify genes, problems, treatments, learn about “junk DNA,” improve sequence technology, create new fields of research

Question 9

What is the gene therapy process?

Answer 9

1) insert RNA version of a normal allele into RNA retrovirus
2) bone marrow removed and cultured from patient, infected with retrovirus
3) viral DNA carrying normal allele inserts into chromosome
4) inject engineered cells into patient

Not super successful

Question 10

How is DNA used for profiling in forensic investigations?

Answer 10

Look at 12 loci on “junk DNA” and sex chromosome (post-electrophoresis)
Junk DNA prevents medical confrontation

Crime sure may be contaminated, suspect must be “major contributor” (thick gel bands means more of that size)

Rape case: use DNA of victim
Maternity / paternity test: child must have half of same alleles as parent

When testifying, give sample frequencies (12 alleles means 1 in 7 billion chance of match)