Band

- In gel electrophoresis, a band represents the dyed or stained molecule you're interested in. In a sample containing two different sized pieces of DNA, there will be two bands on the gel in that lane. The smaller piece of DNA will move more quickly through the gel, so it will be farther from the well. Each band is composed of hundreds of copies of the DNA molecule of that length.
Definition from:
http://www.acad.carleton.edu/curricular/BIOL/classes/bio125/recdna/glossary.html

Base

- The chemical unit that characterises a nucleotide. In DNA, the bases found are adenine (A), guanine (G), thymine (T) and cytosine (C). In RNA, the bases are adenine, guanine, uracil (U) and cytosine.
Definition from:
http://www.igd.cornell.edu/MolecularMarkers/Glossary.pdf

- The molecular building blocks of DNA: adenine (A), cytosine (C), guanine (G), thymine (T). In DNA, A attaches only to T, and C attaches only to G.
Definition from:
http://www.proactivegenetics.com/glossary.dna#b

Base pair ( bp )

- Two nitrogenous bases paired together in double-stranded DNA by weak bonds; specific pairing of these bases (adenine with thymine and guanine with cytosine) facilitates accurate DNA replication; when quantified (e.g., 8 bp), refers to the physical length of a sequence of nucleotides
Definition from:
http://www.genetests.org/servlet/access?qry=ALLTERMS&db=
genestar&fcn=term&gtreport2=true

Buffer  (PCR Buffer)

- PCR buffer is necessary to create optimal conditions for activity of Taq DNA polymerase. Buffers often contain Tris-Hcl, KCl, and sometimes MgCl2. PCR buffers are often available in 10X concentration and are sometimes Taq formulation-specific.
Definition from: http://www.eeescience.utoledo.edu/Faculty/Sigler/RESEARCH/Protocols/PCR/PCR.pdf