Biology, Eighth Edition (Raven)

Chapter 17: Biotechnology

DNA Probe (DNA hybridization)

How do you find a particular DNA sequence in a sample? The isolation of specific DNA sequences from a tissue sample was a challenge for early molecular biologists. Unlike proteins, which have diverse sizes and charges, there is no easy way separate out a specific sequence of DNA based on its general physical and chemical properties. You cannot chemically stain for a specific sequence of DNA. In contrast, it is often possible to use a specific stain to detect a specific protein. Once a DNA sequence is known, the complementary strand can be synthesized and used to detect the strand of interest in a sample.

View the animation below, then complete the quiz to test your knowledge of the concept.


In hybridization
A)two DNAs from the same source combine
B)DNA from two separate sources combine
C)DNA combines with complementary RNA
D)DNA is split into two separate pieces

DNA probes are used to
A)locate complementary RNA sequences in a test sample
B)make homologous DNA
C)make homologous RNA
D)locate a specific DNA nucleotide sequence in a test sample

For DNA probes to hybridize
A)DNA strands must be homologous, having regions with similar or identical nucleotide sequences
B)DNA strands must be non-homologous
C)DNA must be complementary to RNA
D)DNA must be fragmented by reverse transcriptase

Non-homologous DNA will attach to a DNA probe.

At high temperature, two complementary DNA strands will anneal.
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