Overview
Genetic engineering changes genetic material on purpose, and assisted reproduction lets embryos be created, tested and selected outside the body. This topic covers recombinant DNA techniques, selection before and after fertilization, and in vitro fertilization.
- Assisted reproduction refers to medical techniques that support individuals or couples who are facing difficulties in conceiving a child naturally.
- These techniques fall under a broader medical category called Assisted Reproductive Technology (ART).
- ART involves manipulating eggs, sperm, or embryos outside the human body to achieve pregnancy.
- The two most prominent techniques used in ART are In Vitro Fertilization (IVF) and Intracytoplasmic Sperm Injection (ICSI).
- IVF was first successfully performed in 1978, marking a revolutionary breakthrough in reproductive medicine.
- ICSI, developed later, became a major advancement in cases where male infertility is a contributing factor.
Genetic engineering
Genetic engineering is the deliberate modification of the genetic material of cells or organisms. Its basic tool is recombinant DNA technology: restriction endonucleases cut DNA at specific palindromic sequences, DNA ligase joins the fragments, and the recombinant molecule is carried by a vector (plasmid, bacteriophage or viral vector) into host cells, where it is copied and, if wanted, expressed. The gene of interest can also be obtained as cDNA made from mRNA by reverse transcriptase, and amplified by the polymerase chain reaction (PCR).
Applications in medicine include recombinant human proteins (insulin, growth hormone, clotting factors), vaccines, transgenic animal models, and gene therapy, in which a functional gene is delivered into the somatic cells of a patient. Genome editing with CRISPR-Cas9 uses a guide RNA to direct the Cas9 nuclease to a chosen sequence and cut it, so that it can be repaired, disrupted or replaced. Changes in somatic cells affect only the patient, whereas changes in germ cells or embryos would be inherited, which raises serious ethical and legal limits.