(5.1) Introduction to genetic engineering

This section helps you answer questions like ...  What do we mean by genetic engineering?

Discuss the 'Pros and Cons' of GM products.  

Be able to describe the basic principles of how to transfer a gene from one organism's genome to the genome of another organism.

Can you describe some uses of genetic engineering in medicine or agriculture?

Reminders: A chromosome as a thread-like structure of DNA, carrying genetic information in the form of genes.

A gene is a length of DNA that codes for a protein. An allele as a version of a gene.

 

Biotechnology example - bacteria:

Bacteria are useful in biotechnology and genetic engineering due to their rapid reproduction rate and their ability to make complex molecules.

It is not difficult to share their genetic code shared with all other organisms and the presence of plasmids.

Although bacteria are useful in biotechnology and genetic engineering there are concerns e.g. lack of ethical concerns over their manipulation and growth.

The basic idea of genetic engineering is to transfer a gene that gives rise to a desirable characteristic (trait) from one organism's genome to a different organism's genome, so that it acquires that desired characteristic.

• Know and understand in genetic engineering, genes from the chromosomes of humans and other organisms can be ‘cut out’ using enzymes and transferred to cells of other organisms.

• Be able to demonstrate an understanding of the process of genetic engineering, including the removal of a gene from the DNA of one organism and the insertion of that gene into the DNA of another organism
  • This is exemplified by the production of insulin from bacteria by inserting the human insulin gene into bacteria and growing the bacteria to produce lots of insulin quickly and economically efficiently.

  • This amounts to changing the characteristics of an organism by changing its genes.

  • Useful genes from organism A can be inserted into organism B.

  • The desired useful gene (carrying desired characteristic) is cut out and isolated from the source organism A's chromosome by specific enzymes and inserted into a vector.

    • Restriction enzymes recognise specific sequences of DNA and cut the DNA at these points.

    • DNA ligase enzymes are employed to join the two pieces of DNA together at their 'reactive' ends.

    • The two different bits of DNA joined together are known as recombinant DNA.

    • A vector is something used to transfer DNA into the target cell e.g. a plasmid can be used to transfer DNA into a bacteria.

      • A plasmid is a relatively small ring of DNA.

      • They are found in bacteria and fungal yeasts.

    • The vector is usually a virus or a bacterial plasmid - a circular piece of DNA found in bacterial or yeast cells.

    • Plasmids are small circular molecular sections of DNA which can be transferred between bacteria.

    • When the vector is introduced to the target organism, the useful genes inserted into the cell.

  • Other enzymes are then used to remove an 'undesired' gene from organism B, the one you want to modify.

  • Then, via other enzymes, the desired transplanted gene can be inserted into organism B.

  • It is hoped one day to cure the genetic disorder cystic fibrosis with gene therapy i.e. replacing faulty genes with correctly functioning genes.

  • Viruses can have their genes modified to stop them being infective and use to make vaccines.

• Important note on cloning:

  • After plant or animal cells have been genetically modified, it is essential that they transfer the newly introduced genes.

  • Cells are first screened e.g. with an antibiotic, to kill cells that do not have the inserted gene.

  • The cells can then be successfully cloned.

  • This screening procedure is mentioned in the descriptions of insulin production and cloning plants.

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Key points Source of information is based on textbooks & syllabus-specifications for students taking the AQA GCSE, Edexcel GCSE and OCR GCSE level biology examinations (~US grades 9-10).

Key points about genetic engineering

Introduction to Genetic Engineering in Biotechnology

Genetic engineering is the process of altering an organism’s DNA to introduce desirable traits or produce useful substances.

This technology is widely used in biotechnology, medicine, and agriculture.

Scientists use vectors like bacteria and viruses to transfer genes into organisms, enabling genetic modifications.

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1. What Is Genetic Engineering?

Genetic engineering involves manipulating DNA using laboratory techniques to modify genetic material. It is used to:

• Produce medicines, such as insulin and vaccines.

• Improve crops for better yield, disease resistance, and nutrition.

• Develop gene therapy to treat genetic disorders.

This process relies on recombinant DNA technology, which allows genes from one species to be inserted into another.

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2. The Role of Vectors in Genetic Engineering

Vectors are used to transfer genes between organisms.

Common vectors include bacteria and viruses, which efficiently deliver genetic material into target cells.

(A) Bacterial Vectors

• Scientists use plasmids, circular pieces of bacterial DNA, as vectors.

• A gene of interest is inserted into a plasmid using restriction enzymes.

• The recombinant plasmid is introduced into bacteria, which then replicates and produces the desired protein (e.g., insulin in E. coli bacteria).

(B) Viral Vectors

• Viruses naturally insert their genetic material into host cells, making them useful for gene therapy.

• Scientists modify viruses to carry healthy genes instead of harmful ones.

• This technique is used in treating disorders like cystic fibrosis and certain cancers.

Both bacterial and viral vectors help scientists deliver genetic material precisely, making genetic engineering more effective.

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3. Importance in Understanding Human Genetics

Genetic engineering has transformed medicine, agriculture, and scientific research. Understanding it is important for:

• Medical Advancements: Used in gene therapy, cancer treatments, and vaccine development.

• Disease Prevention: Helps correct faulty genes and prevent inherited disorders.

• Biotechnology Innovations: Improves food security, disease resistance in crops, and sustainable agriculture.

• Evolutionary Studies: Allows scientists to explore genetic diversity and adaptation.

Genetic engineering plays a vital role in human health, biotechnology, and scientific discovery.

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Summary of learning objectives and key words or phrases

Understand how genetic engineering is used in biotechnology, including the use of vectors like bacteria and viruses to make GM products..

• In the context of genetic engineering, be able to explain the role of the scientific community in validating new evidence, including the use of:

  • a) scientific journals - enable new findings on genetic engineering to be communicated to other scientists working in the same areas of science, so ideas and knowledge are widely spread AND other scientists can check whether the research is valid eg do other scientists get the same results? do other scientists draw the same conclusions? do other scientists agree with, and find the theory valid?

  • b) the peer review process - a sort of refereeing system, research papers on genetic engineering are read and checked by people competent to understand the contents of research papers (their peers) - this ensures standards are high in terms of 'good scientific practice'.

  • c) scientific conferences enable scientists to meet and present and discuss their findings on genetic engineering, compare their work, listen to new ideas, get ideas to take back to their own research project. Its also a forum for other scientists to hear about research which isn't necessarily exactly their own specialist field, but broadens their own knowledge of related fields of science e.g. genetic engineering.

Be able to demonstrate an understanding of how gene mutations change the DNA base sequence and that mutations can be:

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