Chapter summary 3.1
• DNA can be altered with the help of enzymes. • DNA polymerase produces new DNA polymers, DNA ligase repairs DNA and endonuclease cuts DNA at specific locations. 1 The Cas9 enzyme is linked to a guide RNA sequence to form a complex.
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3 Once the complex has identified the correct DNA sequence, the Cas9 enzyme cuts the strands of the target DNA.
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2 The complex attaches to a matching DNA sequence adjacent to a spacer (yellow segment).
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4 New DNA is inserted and is used by the cell to repair the cut. FIGURE 1 The process of CRISPR
• CRISPR-Cas9 is sourced from prokaryotes and helps protect them from viruses. • Molecular biologists can use the CRISPR-Cas9 system to cut DNA. • PCR is a method of multiplying sections of DNA through heating and cooling steps. • Gel electrophoresis can be used to separate DNA sections according to size and build a DNA profile. • Pieces of DNA, called vectors, can be removed from one organism and inserted into another. • Human insulin can be produced through transformed bacterial cells. • Organisms can be genetically modified by altering the genome. • Organisms are considered transgenic organisms when DNA is transferred from one organism into another. • Scientists must consider the ethical issues involved in genetically modifying organisms.
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100 BIOLOGY FOR VCE UNITS 3 & 4
OXFORD UNIVERSITY PRESS
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