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6.8 Biotechnology

Keywords

English Term 中文翻译 Definition & Explanation
Genetic Engineering 基因工程 The direct manipulation of an organism's genes using biotechnology.
Gel Electrophoresis 凝胶电泳 A technique used to separate DNA fragments based on their size and electrical charge.
Polymerase Chain Reaction PCR (聚合酶链式反应) A method used to rapidly make multiple copies of (amplify) a specific DNA sample.
Bacterial Transformation 细菌转化 The process by which bacterial cells take up foreign DNA from their environment.
DNA Sequencing DNA 测序 The process of determining the precise order of nucleotides (A, T, C, G) within a DNA molecule.

1. Overview of Genetic Engineering

Biotechnology allows scientists to analyze and manipulate DNA and RNA. These techniques are essential for fields ranging from forensic science and medical diagnosis to agricultural development. By manipulating genetic material, we can compare samples, identify specific genes, and even give organisms new traits.

2. Key Techniques in Biotechnology

I. Gel Electrophoresis

This process separates DNA fragments primarily by size and charge.

  • DNA molecules are negatively charged, so they move toward the positive electrode in an electric field.
  • The gel acts as a molecular sieve: smaller fragments move faster and further than larger ones.
  • This results in a "DNA fingerprint" used for comparing sequences from different samples.

II. Polymerase Chain Reaction (PCR)

PCR is used to amplify (mass-produce) DNA fragments through a three-step cycle:

  1. Denaturing: Heating the DNA to separate the two strands.
  2. Annealing: Cooling to allow DNA primers to attach to the original strands.
  3. Extending: DNA polymerase adds nucleotides to synthesize new DNA molecules.

III. Bacterial Transformation

This technique introduces foreign DNA into bacterial cells. Often, a gene of interest is inserted into a circular DNA molecule called a plasmid, which is then taken up by the bacteria. This allows the bacteria to produce proteins (like insulin) encoded by the foreign gene.

IV. DNA Sequencing

DNA sequencing technology determines the exact order of nucleotides in a DNA molecule. This allows researchers to identify mutations, determine evolutionary relationships, and map entire genomes.

3. Applications and DNA Fingerprinting

Most of these techniques can be used to create a DNA fingerprint. Because individuals (except identical twins) have unique DNA sequences, comparing these fingerprints allows for:

  • Paternity testing.
  • Forensic identification in criminal investigations.
  • Diagnosing genetic disorders.

Quiz

Campbell Biology Chapter 20 Practice Test: DNA Tools and Biotechnology

Click the link above to practice related multiple-choice questions on DNA technology.