BLAST

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313

Glossary

1˚

The abbreviation for primary. 1˚ sequence

refers to the letters of DNA, RNA, or pro-

tein. 1˚ transcript refers to an unproc-

essed RNA that still contains its introns.

2˚

The abbreviation for secondary. Most fre-

quently used for generalizing protein and

RNA structures; for example, the α-helix

and hair-pin are common 2˚ structures.

3´

The end of a nucleic acid sequence; often

used with UTR.

5´

The start of a nucleic acid (DNA or RNA)

sequence; often used in conjunction with

UTR (e.g., 5´UTR). Nucleotide sequences

are conventionally written with the 5´ end

at the left. DNA molecules are usually

double-stranded but when written, usu-

ally only the 5´ to 3´ strand is displayed.

The complementary strand has reversed

polarity (3´ to 5´).

aa

The abbreviation for an amino acid that is

often used when describing the length of a

protein (e.g., the average protein is about

300 aa long).

allele

A form of a gene. Typically, the most

common form is called wild-type, and

each allele is given a specific (and often

obscure) name.

amino acid

The basic building block for all proteins.

There are 20 common amino acids.

Arabidopsis thaliana

Known by its common name, thale cress,

this mustard weed is a favorite organism

for plant genetics and molecular biology.

It was the first plant with a complete

genomic sequence. ...