Plant Biotechnology and GMOs – Lecture Notes

A comprehensive set of Q&A flashcards covering plant-derived commodities, biofuels, plant-made proteins, vaccines, cell walls, secondary metabolites, GMO regulation, and plant transformation techniques based on the lecture notes.

What are the main plant-derived commodities humans use from plants?

Starch, oils, protein, and plant cell walls.

What role does starch play in the paper industry, and what are typical starch contents in paper and cardboard?

Starch acts as a thickener and helps paper feel smooth; about 4.1% in paper and 2% in cardboard.

What does iodine testing reveal about starch on paper?

Iodine reacts with starch turning blue/purple.

How is corn starch used to improve latex gloves?

Corn starch reduces stickiness, improving glove performance.

What is a major use of starch in biofuels?

Starch is a main ingredient used to produce bioethanol.

Why are biofuels considered carbon-neutral?

Because CO2 released when fuels are burned is offset by CO2 absorbed by plants during growth.

What is a major economic drawback of increasing starch use for industrial purposes?

Rising food prices due to diversion of starch to industrial uses.

What are the two glucose-based polymers that make up starch?

Amylose and amylopectin.

How can starch be converted into fuel?

Degrade starch to glucose, then ferment glucose with yeast (Saccharomyces) to produce ethanol.

Outline the basic steps to produce ethanol from starch starting with corn or wheat.

Grind and heat the starch, convert to glucose with enzymes, ferment with yeast to ethanol, dehydrate, and blend with petrol.

Besides ethanol, what is another use for starch?

Biodegradable plastics (starch + vegetable oil + water).

How are plant oils used beyond cooking and food?

They can be processed and used for biodiesel; by-products and other industrial uses exist.

How can plant oils be converted into biodiesel?

Transesterification with alcohol to produce biodiesel.

What is a potential renewable source of oils for biodiesel besides land crops?

Algae, which can produce oils for biodiesel.

What are the advantages and current limitations of algae as an oil source?

High oil yields and ability to grow in salt water without soil, but currently expensive and yields must improve. Genetic modification may help.

Why is amino acid balance important in plant proteins?

A proper balance of essential amino acids is necessary for good health.

Which staples lack methionine, lysine, and tryptophan respectively?

Legumes lack methionine; maize lacks lysine and tryptophan.

What is Quality Protein Maize (QPM) and why was it developed?

Maize bred to have increased lysine and tryptophan to improve dietary protein.

What is golden rice and its significance?

Rice fortified with vitamin A to help prevent blindness in children.

How can plants be used as bioreactors for producing proteins?

Animal genes can be introduced into plants to produce antibodies and other proteins that fold well in plants.

What is a plantibody?

Antibodies produced in plants for diagnosis or therapy.

How can vaccines be produced in plants?

Express an epitope from a pathogen to form virus-like particles; higher yields and stable, purified subunits.

What is the advantage of plant-derived vaccine components over microbial production?

Higher yield and potential cost reduction; subunits can be purified or used as stable, non-infectious particles.

Why are plant cell walls relevant to biotechnology and biofuels?

Cell walls provide cellulose for fermentation once bonds to glucose are accessible; however, lignin makes breakdown difficult.

What are the challenges in fermenting plant cell walls for biofuels?

Lignin and complex cross-links hinder enzymatic access to cellulose and hemicellulose.

How can lignin content be modified to improve ethanol production?

Genetic engineering or RNA interference to reduce lignin synthesis, increasing cellulose accessibility.

What is meant by secondary metabolites in plants?

Low-volume, high-price products (e.g., taxol) produced by plants; some can be synthesized chemically.

What is Taxol and why is it valuable?

A mitotic inhibitor used in breast cancer treatment; highly valuable and sourced from the Pacific yew.

Why is Taxol production from natural sources problematic?

The Pacific yew grows slowly; extracting enough for a patient would require many trees, making it unsustainable.

What is a plant cell bioreactor and what cultures are used?

Using plant cells (callus or hairy root cultures) in bioreactors to produce metabolites.

What is a callus in plant tissue culture?

Undifferentiated plant tissue that is totipotent and can regenerate into a whole plant.

What roles do cytokinin and auxin play in tissue culture?

Cytokinin promotes shoots; auxin promotes roots; their balance influences callus formation.

What is Step 2 in plant transformation (why is E. coli used)?

Isolate and prepare plasmid DNA in E. coli, then transfer to plant cells with promoters/terminators that work in eukaryotes.

What is the role of promoters and terminators in plant transformation?

Promoters drive gene expression (constitutive or tissue-specific); terminators signal transcription termination.

How can gene silencing be achieved in plants?

Using antisense RNA or RNA interference to silence target genes.

What is TDNA and what are its borders?

Transfer DNA from Agrobacterium used to insert the gene of interest; bordered by left (LB) and right (RB) sequences.

What is Agrobacterium tumefaciens’ role in plant transformation?

A natural vector that transfers TDNA into plant genomes to create transgenic plants.

What is the difference between indirect and direct transformation methods?

Indirect uses Agrobacterium; direct methods include protoplast transformation or biolistics (gene gun).

What is a gene gun and how does it work?

Biolistic delivery shoots DNA-coated particles (gold/tungsten) into plant cells.

What is the purpose of the selection step in plant transformation?

Identify transformed cells using a selectable marker (antibiotic/herbicide resistance, etc.).

What is a chimera in plant transformation?

An organism containing both transformed and non-transformed cells.

What is plant regeneration in tissue culture?

Regrowing a whole plant from transformed cells during tissue culture.

What is hardening off in plant propagation?

Acclimating tissue-culture plants to external conditions by gradually reducing humidity.

What is SEX4 and what happens when it is silenced?

SEX4 is a starch-degrading enzyme; silencing leads to starch accumulation detected by iodine staining.

Why are reference genes used in gene expression analysis (e.g., PCR)?

To normalize data by ensuring constant expression levels (e.g., beta-tubulin) across samples.

What regulatory criteria do GM crops face in South Africa (SA)?

Assessment of allergenicity, toxicity, changes in composition, and yield; must be functionally equivalent to non-GM plants.

Why is it recommended that GM crops contain a single transgene?

To clearly understand the transgene’s effect and minimize unintended variations.

What is a historical GM crop example that highlighted regulatory testing needs?

The Lenape potato, which had solanine toxicity; underscored the importance of testing.

What is solanine and where is it produced?

A toxic glycoalkaloid produced in potato leaves; can contaminate tubers under certain conditions.