Exercises: Applications of biotechnology

Name two applications of biotechnology in healthcare and briefly explain what each consists of.

Bacteria and other microorganisms play a role in sewage treatment plants. Explain what role they play in water purification.

What is gene therapy? Give an example of a disease targeted by this strategy and explain its underlying principle.

Bt maize incorporates a gene from the bacterium Bacillus thuringiensis that produces an insecticidal toxin. State two advantages of this GM crop and two risks or criticisms raised against it.

The diagram summarises, in four numbered stages, how human insulin is produced today. Explain what happens in each stage and account for the advantages this method offers compared to extracting insulin from pig or cattle pancreases.

Bioremediation uses microorganisms to clean up hydrocarbon spills. Explain what this technique consists of and what conditions must be met for the microorganisms to effectively degrade the pollutant.

During the development of an mRNA vaccine against an enveloped pathogenic virus, the research team must overcome several physiological and cellular obstacles:

1. a) If free mRNA were injected directly into the bloodstream, it would be degraded within minutes and would be unable to cross the plasma membrane. Justify what biological barriers (molecular and electrostatic) prevent its entry, and explain how encapsulation in lipid nanoparticles solves this problem.
2. b) Once in the host cell cytosol, describe which organelle translates the mRNA and refute the erroneous claim that "mRNA vaccines can permanently alter the patient's genome," providing two biological arguments based on the flow of genetic information and cellular compartmentalization.
3. c) Compare the safety of this vaccine with a traditional attenuated virus vaccine in an individual with severe immunodeficiency: predict what risk of reversion or pathogenic replication the attenuated vaccine poses that does not exist at all with the mRNA vaccine, and justify your reasoning.

In a forensic investigation, a minute bloodstain is found on a victim's clothing (Sample). The police interrogate two suspects (S1 and S2). In addition, in a parallel civil case, a woman (M) claims paternity of her child (C) from S1. The laboratory analyzes three short tandem repeat (STR) loci:

1. a) Interpret the forensic results: can either of the suspects be ruled out? Does this match allow one to state with absolute $100\ \%$ certainty that the non-excluded suspect is the perpetrator of the crime? Justify your answer considering statistical probability and the need to analyze more loci.
2. b) Analyze the paternity test data: deduce the obligate paternal alleles that the child (C) must have received by comparing their genotype with that of their mother (M). Based on these, determine with reasoned arguments whether S1 can be the biological father of C.
3. c) Explain at the chromosomal and molecular level what it means for an individual to exhibit two different values at an STR locus versus only one (as in Locus 3 of S1), and what analytical technique allows these alleles to be distinguished after PCR amplification.

A biomedical consortium proposes applying CRISPR/Cas9 technology to viable human zygotes to correct an autosomal dominant mutation responsible for Huntington's disease prior to embryo implantation.

1. a) Describe the two essential molecular components of the CRISPR/Cas9 system that must be microinjected into the zygote, and explain how they act in coordination to recognize and accurately cut the target DNA sequence.
2. b) In experimental trials, two major technical problems are detected: off-target cuts and genetic mosaicism (some cells of the blastocyst carry the edit while others retain the original unedited allele). Justify at the molecular and embryonic developmental level why mosaicism arises, and predict what health consequences it would entail for the resulting individual.
3. c) Distinguish precisely between somatic gene editing and germline gene editing. Scientifically justify why germline modification in embryos faces far greater ethical and legal opposition in the international community than gene therapy applied to the somatic cells of an adult patient.

Unit challenge. Take on the role of a scientific advisor and prepare a technical report on the real impact of biotechnology on our environment.

1. Gathering official data: Access the website of the Ministry of Agriculture, Fisheries and Food (MAPA) and compile the cultivated area (in hectares) of genetically modified maize ($MON\,810$) in Spain over the last three available years.

2. Basics of genetic engineering: Create an explanatory diagram of the biotechnological process used to generate this GMO, detailing the use of restriction enzymes, cloning vectors, DNA ligase, and methods for gene transfer and integration.

3. Analysis of applications: Compare this agronomic application with a medical one (such as the production of recombinant insulin or a therapy using $CRISPR/Cas9$), calculating the percentage variation in cultivated area to one decimal place (for example, $+2.5\,\%$).

4. Bioethical assessment: Write a final reasoned proposal evaluating environmental sustainability, gene flow to wild species, and the socioeconomic impact of using biotechnological patents.

Assessment criteria:

• Conceptual precision in describing recombinant DNA tools and stages.

• Rigour in obtaining, tabulating, and carrying out percentage analysis of official MAPA data.

• Critical and integrated argumentation regarding agricultural and biomedical applications from a bioethical perspective.