5’-CGCACCTGTGTTGATCACCTAGCCGATCCACGGTGGATCCAAGGC-3’
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3’-GCGTGGACACAACTAGTGGATCGGCTAGGTGCCACCTAGGTTCCG-5’
Tip: If you want to see a review of PCR, we recommend this amazing animation and virtual lab made by the University of Utah.
You also have a collection of short DNA primers:
Primer 1: 5’-CGTGGA-3’
Primer 2: 5’-TGTGTT-3’
Primer 3: 5’-ATCCAA-3’
Primer 4: 5’-CCTTGG-3’
You put together several reaction mixtures, run them in the thermocycler under conditions that should produce a product if the reaction mixture is correct.
All mixtures contain:
5’-CGCACCTGTGTTGATCACCTAGCCGATCCACGGTG
GATCCAAGGC-3’
The 45 bp DNA fragment
DNA polymerase that can function at high temperature
The necessary buffer conditions
For each mixture, indicate whether or not the PCR reaction would produce a product. If a product would be produced, give the length of that product in base-pairs (bp); if no product would be produced, give zero “0” for the length.
1
Added: dATP, dGTP, dCTP, Primer 2, Primer 4
- unanswered
2
Added: dATP, dGTP, dCTP, dTTP, Primer 2
- unanswered
3
Added: dATP, dGTP, dCTP, dTTP, Primer 2, Primer 4
- unanswered
4
Added: dATP, dGTP, dCTP, dTTP, Primer 1, Primer 3
- unanswered
5
Added: dATP, dGTP, dCTP, dTTP, Primer 2, Primer 3
To determine whether a PCR reaction would produce a product and the length of that product, we need to compare the DNA sequence of the template with the DNA sequences of the primers.
In each reaction mixture, the template DNA sequence is:
5’-CGCACCTGTGTTGATCACCTAGCCGATCCACGGTG
GATCCAAGGC-3’
Let's analyze each reaction mixture:
1. Added: dATP, dGTP, dCTP, Primer 2, Primer 4
To check if a product would be produced, we need to look for complementary regions between the template DNA sequence and the primers. Primer 2 is 5’-TGTGTT-3’ and Primer 4 is 5’-CCTTGG-3’.
There is no exact match for Primer 2 or Primer 4 in the template DNA sequence, so a product would not be produced. The length of the product would be 0 bp.
2. Added: dATP, dGTP, dCTP, dTTP, Primer 2
Again, we need to look for complementary regions between the template DNA sequence and Primer 2.
Primer 2 (5’-TGTGTT-3’) has a partial match with the template DNA sequence at the beginning. The complement of Primer 2 on the template is 5’-ACACA-3’. Therefore, a product would be produced with a length of 5 base pairs (bp).
3. Added: dATP, dGTP, dCTP, dTTP, Primer 2, Primer 4
Now we need to consider both Primer 2 and Primer 4 to check for complementary regions.
As previously mentioned, Primer 2 (5’-TGTGTT-3’) has a partial match with the template DNA sequence. Primer 4 (5’-CCTTGG-3’) does not have a perfect match within the template.
Therefore, a product would be produced with a length of 5 bp.
4. Added: dATP, dGTP, dCTP, dTTP, Primer 1, Primer 3
Primer 1 (5’-CGTGGA-3’) and Primer 3 (5’-ATCCAA-3’) need to be checked for complementary regions within the template DNA sequence.
Primer 1 has a partial match at the beginning, with a complement of 5’-TGCCTG-3’. Primer 3 does not have an exact match within the template sequence.
Therefore, a product would be produced with a length of 6 bp.
5. Added: dATP, dGTP, dCTP, dTTP, Primer 2, Primer 3
We already checked Primer 2 in the previous mixtures, so let's focus on Primer 3 (5’-ATCCAA-3’).
Primer 3 does not have a perfect match within the template DNA sequence.
Therefore, a product would not be produced. The length of the product would be 0 bp.
To summarize:
1. No product, length = 0 bp
2. Product, length = 5 bp
3. Product, length = 5 bp
4. Product, length = 6 bp
5. No product, length = 0 bp