Biotech quiz 1

Artificial selection

Choosing parents with desirable traits and breeding them over many generations so those traits become common.

Example of artificial selection

Dog breeds, corn/maize domestication from teosinte, wheat breeding for larger seeds.

Genetic engineering

Directly changing an organism’s DNA by inserting, deleting, or editing genes.

Example of genetic engineering

Inserting the human insulin gene into E. coli, CRISPR gene editing, Golden Rice with beta-carotene genes.

Speed of artificial selection vs genetic engineering

Artificial selection is slow (many generations); genetic engineering is fast (single-generation changes).

Precision of artificial selection vs genetic engineering

Artificial selection is less precise (many linked traits changed); genetic engineering is highly targeted (specific gene changes).

Scope of artificial selection vs genetic engineering

Artificial selection is limited to existing variation; genetic engineering can introduce new sequences from anywhere.

Risks of artificial selection

Reduced genetic diversity, inbreeding depression, unintended linked traits.

Risks of genetic engineering

Off-target effects, ecological/ethical concerns, regulatory or societal issues.

Domestic dogs and recombinant insulin methods

Dogs are produced by artificial selection; recombinant insulin is produced by genetic engineering.

True or False: All GMOs are the result of artificial selection.

False. GMOs are those whose genomes were directly altered (genetic engineering), while artificial selection does not produce GMOs.

Mnemonic for artificial selection vs genetic engineering

"Select = Choose parents; Engineer = Edit DNA".

Biotechnology from ancient times example

Fermentation, where microbes transform food (e.g., yeast in bread, beer, wine).

Selective breeding/domestication

Changing allele frequencies in crops/animals through the selection of favorable traits.

Grafting

Joining tissues of two plants so they grow as one, combining desirable fruit varieties with disease-resistant roots.

Four major application fields of biotechnology

Medical/Healthcare, Agricultural, Industrial (bioprocessing), Environmental.

Example of medical biotech

Recombinant protein drugs, like insulin made in E. coli.

Example of agricultural biotech

Genetically modified crops, such as Bt corn or herbicide-tolerant soy.Producing food with desired traits.

Example of industrial biotech

Fermentation in bioreactors to produce enzymes or biofuels.

Example of environmental biotech

Bioremediation using microbes to break down pollutants.

Restriction enzymes

Proteins from bacteria that cut DNA at specific sequences, part of bacterial defense against phages.

Recognition site

Short DNA sequence recognized by restriction enzymes, often palindromic.

Sticky ends vs blunt ends

Sticky ends have overhangs for easier ligation, blunt ends are straight cuts with no overhang.

EcoRI

A restriction enzyme that recognizes 5’-GAATTC-3’ and leaves a 5’-AATT overhang.

Type II restriction enzymes

Enzymes widely used in labs for predictable cuts at specific recognition sites.

Methylation and restriction enzymes

Methylation protects DNA from being cut by restriction enzymes.

DNA ligase function

Seals DNA fragments together by forming phosphodiester bonds.

T4 DNA ligase

Commonly used ligase in vitro that uses ATP for forming phosphodiester bonds.

Efficiency of ligase

Less efficient with blunt ends, low concentration, or incompatible ends; can improve success with tricks.

Plasmid definition

Small, circular, double-stranded DNA molecule replicating independently in bacteria.

Uses of plasmids in biotechnology

Clone genes, express proteins, deliver DNA, create libraries, perform assays.

Selectable marker example

bla gene conferring ampicillin resistance, allowing identification of plasmid-containing cells.

Multiple cloning site (MCS)

Region with many unique restriction sites for easy insertion of DNA fragments.

Cloning vector vs expression vector

Cloning vectors are optimized for inserting DNA; expression vectors enable protein production.

Copy number

Number of plasmid copies per cell; high copy yields more product but may cause instability.

Cloning workflow steps

Design insert, PCR amplify, digest, purify, ligate, transform, plate, screen.

Blue-white screening function

Uses lacZ gene; blue colonies indicate no insert, white colonies indicate successful cloning.

Confirming a clone's correctness

Methods include colony PCR, restriction digest, and Sanger sequencing.

Dephosphorylation of vector

Removes 5’ phosphates to prevent self-ligation and increase insert ligation success.