Genetic modification and biotechnology

Topic 3.5

Essential idea: Biologists have developed techniques for artificial manipulation of DNA, cells and organisms.


3.5.U1 Gel electrophoresis is used to separate proteins or fragments of DNA according to size

In gel electrophoresis DNA fragments move in an electric field and separate from each other according to their sizes. The smallest fragments will move the farthest distance from the origin of the DNA sample.

Gel electrophoresis explained

3.5.U2 PCR can be used to amplify small amounts of DNA

How does Polymerase Chain Reaction work?

Polymerase chain reaction (PCR) is used by scientist to copy and amplify minute quantities of DNA. The procedure is outlined in the figure below.

Polymerase Chain Reaction

3.5.U3 DNA profiling involves a comparison of DNA

DNA profiling involves the use of PCR and gel electrophoresis of DNA

DNA profiling using microsatellites

3.5.U4 Genetic modification is carried out by gene transfer between species

Gene transfer between species

3.5.U5 Clones are groups of genetically identical organisms, derived from a single original parent cell

Defining cloned cells

3.5.U6 Many plant species and some animal species have natural methods of cloning

Examples of clones in plants and animals

3.5.U7 Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells

Cloning using embryo splitting

3.5.U8 Methods have been developed for cloning adult animals using differentiated cells

Different cloning methods


3.5.A1 Use of DNA profiling in paternity and forensic investigations

What is DNA profiling?

DNA profiling involves the use of gel electrophoresis of DNA. Answer the question in Figure 2 and click on the figure to show the correct answer then double click on the figure to return to the gel electrophoresis. Using Figure 1 and 2 describe how DNA profiling is carried out.

Analysis of DNA profile
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DNA profile explained

Analyse the DNA profiles below to determine and explain which suspect was present at the crime scene.

Place mouse pointer on the figure to see conclusions of DNA analysis.

Analysis of DNA profile

3.5.A2 Gene transfer to bacteria using plasmids making use of restriction endonucleases and DNA ligase

Basic technique used in gene transfer

E. coli is used in gene technology because some of its DNA is found on plasmids (smaller circles of DNA). These plasmids can be removed and cleaved by restriction enzymes at target sequences. DNA fragments from another organism can also be cleaved by the same restriction enzyme, and these pieces can be added to the open plasmid and spliced together by ligase. The recombinant plasmids formed can be inserted into new host cells and cloned. When genes are transferred between species, the amino acid sequence of polypeptides translated from them is unchanged because the genetic code is universal.The basic technique in gene transfer is outlined below.

plasmid cloning link plasmid cloning animation
Basic technique in gene transfer

3.5.A3 Assessment of the potential risks and benefits associated with genetic modification of crops

Genetic modification

3.5.A4 Production of cloned embryos produced by somatic-cell nuclear transfer

Cloning using differentiated animal cells

A technique in human cloning

Can you identify some of the ethical issues of therapeutic cloning in humans?

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DNA profile explained


3.5.S1 Design an experiment to assess one factor affecting the rooting of stem-cuttings

Go to Internal Assessment: Design

3.5.S2 Analysis of examples of DNA profiles

Click on Analysis of DNA profiles for practice

Analysis of DNA profiles

3.5.S3 Analysis of data on risks to monarch butterflies of Bt crops

Introdution to Bt toxin gene

Introduction to the Bt toxing gene

Results and Discussion of Bt crops

Place your mouse on graphs to view discussion of Results

Results and Discussion of Results of Bt crops
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