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Biotechnology and Genetic Engineering - Genetic engineering

Grade 11IGCSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Genetic engineering involves changing the genetic material of an organism by removing, changing, or inserting individual genes from another organism.

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Restriction enzymes are used to cut DNADNA at specific base sequences, often leaving 'sticky ends' (short lengths of unpaired bases).

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The enzyme DNADNA ligase is used to join the 'sticky ends' of the target gene and the vector DNADNA together to form recombinant DNADNA.

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Vectors are used to deliver the gene into the host cell; common vectors include bacterial plasmids (circular DNADNA) and viruses.

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Production of human insulin: The gene for human insulin is inserted into Escherichia coliEscherichia\ coli (E. coliE.\ coli) bacteria, which then multiply in fermenters to produce large quantities of the hormone.

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Genetically Modified (GMGM) crops are engineered for traits such as herbicide resistance, pest resistance (e.g., BtBt cotton), or increased nutritional value (e.g., Golden Rice with enhanced Vitamin A/C20H30OC_{20}H_{30}O).

📐Formulae

Target DNA Fragment+Plasmid Vector→DNA LigaseRecombinant DNA\text{Target DNA Fragment} + \text{Plasmid Vector} \xrightarrow{\text{DNA Ligase}} \text{Recombinant DNA}

Double-stranded DNA→Restriction EnzymeDNA Fragments with Sticky Ends\text{Double-stranded DNA} \xrightarrow{\text{Restriction Enzyme}} \text{DNA Fragments with Sticky Ends}

💡Examples

Problem 1:

Explain the role of restriction enzymes and DNADNA ligase in the production of a GMGM bacterium that can produce human insulin.

Solution:

  1. Restriction enzymes are used to 'cut' the insulin gene out of human DNADNA and to cut the bacterial plasmid, creating matching sticky ends. 2. The human insulin gene and the plasmid are mixed. 3. DNADNA ligase is added to join the sugar-phosphate backbones of the human DNADNA and the plasmid DNADNA, resulting in a recombinant plasmid.

Explanation:

By using the same restriction enzyme, the unpaired bases (sticky ends) of the gene and the plasmid will be complementary (e.g., AA pairing with TT), allowing the DNADNA ligase to permanently seal the bond.

Problem 2:

A farmer uses crops resistant to the herbicide Glyphosate (C3H8NO5PC_3H_8NO_5P). What is the biological advantage of this genetic modification?

Solution:

The GMGM crop contains a gene that allows it to break down or ignore the effects of C3H8NO5PC_3H_8NO_5P.

Explanation:

This allows the farmer to spray the entire field with the herbicide; the weeds are killed, but the GMGM crop survives, reducing competition for nutrients, light, and H2OH_2O, thereby increasing yield.

Genetic engineering - Revision Notes & Key Diagrams | IGCSE Grade 11 Biology