Biology, Eighth Edition (Raven)

Chapter 18: Genomics

Sanger Sequencing

How is DNA sequencing different from DNA fingerprinting? DNA sequencing is a technique for determining the complete sequence of bases (As, Ts, Gs, and Cs) for a particular piece of DNA. A genome project is the sequencing of a complete genome (all the DNA in one human being, dog, fly, worm, plant, etc.). Sequencing is relatively time consuming as the process must be done to fairly short lengths of DNA at a time. DNA fingerprinting looks for a specific, short sequence of DNA across the genome and compares the number and locations of this sequence between different individuals. It is a technique for identifying individuals and associating relatives. DNA fingerprinting provides a relatively small amount of information about overall DNA sequences.

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


The primer used in Sanger sequencing
A)can have any nucleotide sequence
B)must have a sequence beginning and ending with the same nucleotide
C)has a nucleotide sequence complementary to the 3' end of the region to be copied
D)has a nucleotide sequence complementary to the 5' end of the region to be copied

To carry out Sanger sequencing a mixture is needed containing
A)single-stranded DNA
B)DNA polymerase
C)four deoxyribonucleotides A, T, C, G
D)all of the above

When a dideoxyribonucleotide is added to the tube
A)replication of the strand continues
B)replication of the strand stops
C)replication of the strand is not affected
D)replication of the strand is speeded up

To sequence DNA by this method, the DNA must first be made in single stranded form.

Examining the electrophoresis gel and reading from bottom to top, one base at a time, gives the sequence of DNA.
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