After listening to the in-class explanation of PCR, reading your
background information and studying the diagrams provided, answer
the following questions.
1. Briefly explain the steps involved
in normal DNA replication within a cell before mitosis.
2. What is the function of each of
the following in a PCR reaction?
3. Briefly describe what the thermocycler (PCR machine) does and what happens in each of the following three steps of Polymerase Chain Reaction:
4. Suppose you start with one double-stranded
molecule of DNA and you want to amplify this one DNA molecule
by PCR. You add an excess of a two single-stranded primers, each
of which will anneal to the DNA molecule in only one place, copying
the segment of DNA between them. Draw representations of the DNA
and primers in each of 3 cycles. Label the template DNA, the primers,
and the newly synthesized DNA strands. Show the direction of DNA
synthesis on each strand.
How many molecules of double-stranded
DNA will you have after three cycles? After six cycles? After
5. Compare the normal process of
DNA replication within a cell to the artificial replication of
DNA molecules in a PCR machine. Describe what is different between
these two processes.
6. What kinds of changes to chromosomes
would cause a "polymorphism" to appear in the DNA profiles
of different individuals from a population?
How would a deletion in the chromosome
of one individual cause a band to run closer to the wells in a
|Science Education Connection
Department of Biochemistry
The University of Arizona
May 1, 1997