生物信息学主要英文术语及释义
生物信息学主要英文术语及释义
Coding region of DNA. See CDS.
Expressed Sequence Tag (EST) （表达序列标签）
Randomly selected, partial cDNA sequence; represents it's corresponding mRNA. dbEST is a large database of ESTs at GenBank, NCBI.
FASTA （一种主要数据库搜索程序）
The first widely used algorithm for database similarity searching. The program looks for optimal local alignments by scanning the sequence for small matches called "words". Initially, the scores of segments in which there are multiple word hits are calculated ("init1"). Later the scores of several segments may be summed to generate an "initn" score. An optimized alignment that includes gaps is shown in the output as "opt". The sensitivity and s
peed of the search are inversely related and controlled by the "k-tup" variable which specifies the size of a "word". (Pearson and Lipman)
Extreme value distribution（极值分布）
Some measurements are found to follow a distribution that has a long tail which decays at high value s much more slowly than that found in a normal distribution. This slow-falling type is called the extreme value distribution. The alignment scores between unrelated or random sequences are an example. These scores can reach very high value s, particularly when a large number of comparisons are made, as in a database similarity search. The probability of a particular score may be accurately predicted by the extreme value distribution, which follows a double negative exponential function after Gumbel.
False negative（假阴性）
A negative data point collected in a data set that was incorrectly reported due to a failure of the test in avoiding negative results.
False positive （假阳性）
A positive data point collected in a data set that was incorrectly reported due to a failure of the test. If the test had correctly measured the data point, the data would have been recorded as negative.
Feed-forward neural network （反向传输神经网络）
Organizes nodes into sequence layers in which the nodes in each layer are fully connected with the nodes in the next layer, except for the final output layer. Input is fed from the input layer through the layers in sequence in a “feed-forward” direction, resulting in output at the final layer. See also Neural network.
Filtering (window size)
During pair-wise sequence alignment using the dot matrix method, random matches can be filtered out by using a sliding window to compare the two sequences. Rather than comparing a single sequence position at a time, a window of adjacent positions in the two
sequences is compared and a dot, indicating a match, is generated only if a certain minimal number of matches occur.
Filtering （过滤）
Also known as Masking. The process of hiding regions of (nucleic acid or amino acid) sequence having characteristics that frequently lead to spurious high scores. See SEG and DUST.
Finished sequence（完成序列）
Complete sequence of a clone or genome, with an accuracy of at least 99.99% and no gaps.
Fourier analysis
Studies the approximations and decomposition of functions using trigonometric polynomials.
Format (file)（格式）
Different programs require that information be specified to them in a formal manner, using particular keywords and ordering. This specification is a file format.
Forward-backward algorithm
Used to train a hidden Markov model by aligning the model with training sequences. The algorithm then refines the model to reduce the error when fitted to the given data using a gradient descent approach.comparisons
FTP (File Transfer Protocol)（文件传输协议）
Allows a person to transfer files from one computer to another across a network using an FTP-capable client program. The FTP client program can only communicate with machines that run an FTP server. The server, in turn, will make a specific portion of its tile system available for FTP access, providing that the client is able to supply a recognized user name and password to the server.
Full shotgun clone （鸟法克隆）
A large-insert clone for which full shotgun sequence has been produced.
Functional genomics（功能基因组学）
Assessment of the function of genes identified by between-genome comparisons. The function of a newly identified gene is tested by introducing mutations into the gene and then examining the resultant mutant organism for an altered phenotype.
gap （空位/间隙/缺口）

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