BIO 111 an der University of Zürich

Wrong

Hybridization can be performed with two DNA strands, with two RNA strands, or with one strand of RNA and one strand of DNA.

Useful for forensic analysis, prenatal diagnosis, biopsy analysis, etc.

Using PCR, you can amplify a DNA fragment starting with as little as 1 cell!

Using PCR, DNA has been amplified (and then cloned) from Egyptian mummies, from Oetzi, even from Neanderthal bones!!! This also shows how stable DNA is.

However, no DNA has ever been amplified successfully from Dinosaurs (Jurassic Park is bogus!)

Note that because PCR is so sensitive, you also have to be very careful about not contaminating your DNA sample!

-Restriction enzymes

-Recombination enzymes (not covered)

Restriction enzymes that recognize the same sequence and cut at the same position are known as isoschizomers.

If they recognize the same sequence but cut at different positions, they are neoisoschizomers.

- Circularization of the vector

- Circularization of the host fragment

- Joining of two vectors together

- Insertion of a single donor DNA fragment into the vector

- Insertion of multiple donor DNA fragments

- Many others!

Result: many different recombinant molecules, and only one copy of each of them!

...by altering their gene expression pattern

- bacteria can synthesize all important building blocks on their one, or can import building blocks from the environment of the cell

- more effective (requires less energy) to import than to synthesize

- bacteria can sense wich moleculaes are present in the environment and respond accordingly (genes are either repressed or expresssed depending if particular molecule is present or not)

PCR is basically in vitro DNA replication; it will thus require a single-stranded DNA template, a primer, a DNA polymerase, and dNTPs.

1. Strand separation is achieved through heat, not through helicases.

->The DNA polymerase must thus be able to withstand high temperatures. All PCR polymerases come from bacteria that live in very hot places (hot springs, ocean vents).

2. In PCR, the molecular biologist adds specific primers to the reaction, rather than letting DNA primase synthesize primers everywhere.

Thus, only a specific segment of DNA will be replicated. (Hot spring in Yellowstone National Park, USA the home of Thermus aquaticus, the source of Taq DNA polymerase.)

negative inducible

Before 1980s: type I diabetics must take insulin isolated from pancreas (Bauchspeicheldrüse) of slaughtered animals (pigs).

The idea was to express the human insulin gene in bacteria (same gentic code!) at high levels, purify the protein, give it to patients instead of the animal insulin.

Advantages

-No immune reaction (human protein)

-pure protein (no containments)

-no risk of transfer of animal diseased (viruses, prions)

-Cheap

Is the engineering of biology: the synthesis of complex, biologically based (or inspired) systems, which display functions that do not exist in nature.