Functional assessment of every gene in the mammalian cell is an on-going challenge. Understanding, not only the function of each gene in isolation but the complexity of functional networks and control systems is of particular importance for discovery of novel and valid drug targets. Answering complex biological questions in this context necessitates high- throughput gene functional characterization using an array of genomic, proteomic and in silico- based tools and technologies.  

Related glossaries include  Metabolic engineering,   Phylogenomics Drug discovery & development    Proteomics  
Informatics Bioinformatics,    Drug discovery & development informatics    Genomic informatics    Protein informatics
Technologies Genomic technologies     PCR,      Genetic Manipulation & disruption,     Microarrays
Biology Cell biology,    Chemistry & biology     Expression     Gene Definitions,    SNPs & genetic variations   Nomenclature, particularly of genes in humans and in Model & other Organisms is an increasing challenge as comparing completed genomes becomes increasingly possible.  -Omes & omics

age: The time period elapsed since an identifiable point in the life cycle of an organism. (If a developmental stage is specified, the identifiable point would be the beginning of that stage. Otherwise the identifiable point must be specified such as planting). https://www.ebi.ac.uk/ols/ontologies/efo/terms?short_form=EFO_0000246

A good illustration of the challenges inherent in cross species comparisons. 

biochemical function: My research is concerned with the three-dimensional structures of proteins and their biochemical functions. Gregory Petsko, Brandeis University, 2007 http://www.bio.brandeis.edu/faculty01/petsko.html

biological function: One key problem in this discussion involves the definition of "biological function".  Geneticists, cellular biologists, structural biologists, bioinformaticians, and biophysical chemists use this term to mean different things.  Some speakers used the word "function" to refer to the general biochemical activity of the gene produce (e.g. kinase activity), others referred to the cellular process in which the gene product is involved, while to others "function" meant an understanding of the details of the atomic mechanism of catalysis or recognition.  Still others referred to function in the genetic sense of a generalized phenotype.  This lack of consensus in defining what aspect of function one might learn about from an examination of protein structure prevented the group from reaching a consensus on the role that large scale structural genomics will have in the related area of functional genomics.  G. T. Montelione and S. Anderson, Report to the National Science Foundation:  Workshop on Structural Genomics - Understanding Proteins Universal to Life" Advanced Photon Light Source, Argonne Natl. Laboratories, Jan. 23 - 25, 1998 

biological function The Gene Ontology (GO) provides a framework and set of concepts for describing the functions of gene products from all organisms. It is specifically designed for supporting the computational representation of biological systems. A GO annotation is an association between a specific gene product and a GO concept, together making a statement pertinent to the function of that gene. However, the meaning of the term “function” is not as straightforward as it might seem, and has been discussed at length in both philosophical and biological circles. Here, I first review these discussions. I then present an explicit formulation of the biological model that underlies the GO and annotations, and discuss how this model relates to the broader debates on the meaning of biological function. The Gene Ontology and the Meaning of Biological Function, Paul D. Thomas  The Gene Ontology Handbook pp 15-24|, 2016 https://link.springer.com/protocol/10.1007/978-1-4939-3743-1_2/fulltext.html

Related terms: biological process, Gene Ontology (GO)  Broader term: function

biological process: A biological objective to which the gene or gene product contributes. Gene Ontology Consortium "Gene Ontology: tool for the unification of biology Nature Genetics 25: 25-29 May 2000

A biological process is accomplished via one or more ordered assemblies of molecular functions. Usually there is some temporal aspect to it, although a process event may be essentially instantaneous. It often involves transformation, in the sense that something goes into a process and something different comes out of it. ...  A biological process is not equivalent to a pathway. We are specifically not capturing or trying to represent any of the dynamics or dependencies that would be required to describe a pathway. [The semantic distinction between a biological process and a molecular function can, at times, be hard to draw, and GO takes a pragmatic, rather than dogmatic, approach: As a general rule a process must have >1 distinct steps.] Gene Ontology Consortium General Documentation, 2001  http://www.geneontology.org/doc/GO.doc.html

comparative genomics: "We believe that the problem of the genome- phenotype connection, which, in a sense, is the central theme of biology, can be solved only through an experimental program strategically planned on the basis of comparative- genomic results. Much of the biological research of the next few decades is likely to develop along these lines. E. Koonin et al "The Impact of Comparative Genomics on our Understanding of Evolution" Cell 101:573-576 June 9, 2000 

Insights can be biochemical, genetic, metabolic or physiological. The practice of uncovering the functions of human genes and other DNA regions by studying their parallels in nonhumans. 
Related terms: biological process, molecular function,  Gene Ontology Consortium; Cell biology cellular components; Maps genomic & genetic comparative genome mapping; Model & other organisms; Phylogenomics comparative proteomics, evolutionary genomics,  Narrower terms: comparative plant genomics, vertebrate comparative genomics
Background on Comparative Genomic Analysis, NHGRI, 2007 http://www.genome.gov/10005835  
Wikipedia http://en.wikipedia.org/wiki/Comparative_genomics   

deductive genomics:  deductive genomics, or large-scale forward genetics, bridges the gap between sequence and function by providing a function-driven in vivo screen of a highly orthologous mammalian model genome for medically relevant physiological functions and drug targets. This approach allows drug discovery to move beyond the focus on sequence-driven identification of new members of classical drug-able protein families towards the biology-driven identification of innovative targets and biological pathways. Deductive genomics: a functional approach to identify innovative drug targets in the post-genome era. Stumm G, Russ A, Nehls M., Am J Pharmacogenomics. 2(4): 263- 271, 2002 

function: The vagueness of the term 'function' when applied to genes or proteins emerged as a particular problem, as this term is colloquially used to describe biochemical activities, biological goals and cellular structure. Gene Ontology Consortium "Gene Ontology: tool for the unification of biology Nature Genetics 25: 25-29 May 2000 

function as conceived by molecular biologists (in what could be called the “molecular biology paradigm”) refers to specific, coordinated activities that have the appearance of having been designed for a purpose. That apparent purpose is their function. The appearance of design derives from natural selection, so many biologists now favor the use of the term “biological program” to avoid connotations of intentional design. Following this convention, biological programs, when executed, perform a function; that is, they result in a particular, previously selected outcome or causal effect. Biological programs are nested modularly inside other, larger biological programs, so a protein can be said to have functions at multiple levels.  The Gene Ontology defines the “universe” of possible functions a gene might have, but it makes no claims about the function of any particular gene. Those claims are, instead, captured as “GO annotations.” A GO annotation is a statement about the function of a particular gene…The Gene Ontology (GO) considers three distinct aspects of how gene functions can be described: molecular function, cellular component, and biological process.   In this representation, a gene encodes a gene product, and that gene product carries out a molecular-level process or activity (molecular function) in a specific location relative to the cell (cellular component), and this molecular process contributes to a larger biological objective (biological process) comprised of multiple molecular-level processes.  The Gene Ontology and the Meaning of Biological Function, Paul D. Thomas  The Gene Ontology Handbook pp 15-24|, 2016 https://link.springer.com/protocol/10.1007/978-1-4939-3743-1_2/fulltext.html

Narrower terms:  biological function, gene function; Proteomics protein function. Related terms: Gene Ontology ^TM ;  Omes & omics functome, transcriptome

functional genome annotation: Functional annotation of the genome is primarily hampered by the lack of a unified transcript index. Current transcript information still largely consists of anonymous and highly redundant ESTs. The situation is further complicated by extensive splicing variation and elusive gene expression. To address these problems, the Ensembl consortium relies initially on computational prediction, followed by confirmation with EST/ protein alignments... We have found evidence for a large number of transcriptional units (65,000- 75,000) and performed initial annotation and classification. The effective study of transcription and protein function requires the compilation of all available evidence of transcription and protein homology. FA Wright et. al. A draft annotation and overview of the human genome, Genome Biology 2(7): 2001 https://www.ncbi.nlm.nih.gov/pubmed/11516338

functional genomics:  The development and application of global (genome- wide or system- wide) experimental approaches to assess gene function by making use of the information and reagents provided by structural genomics [in the original more limited sense of construction of high- resolution genetic, physical and transcript maps of an organism]. It is characterized by high throughput or large- scale experimental methodologies combined with statistical and computational analysis of the results. The fundamental strategy is to expand the scope of biological investigation from studying single genes or proteins to studying all genes or proteins at once in a systematic fashion. Phil Hieter and Mark Boguski "Functional Genomics: It's All How You Read It" Science 278: 601- 602, October 24, 1997

Functional genomics aims to discover the biological function of particular genes and to uncover how sets of genes and their products work together in health and disease. In its broadest definition, functional genomics encompasses many traditional molecular genetic and other biological approaches. 

Wikipedia https://en.wikipedia.org/wiki/Functional_genomics

Related terms: biological process,  genome function,  molecular function, Metabolic profiling networks, pathways,  physiological genomics;  Phylogenomics comparative genomics, homology, phylogenomics,

functional genomics data: A useful way to tackle noise and complexity of functional genomics information is to average the data from many different genes into broad 'omic categories (Jansen & Gerstein 2000. For instance, instead of looking at how the level of expression of an individual gene changes over a time- course, we can average all the genes in a functional category (e.g. glycolysis) together. This gives a more robust answer about the degree to which a functional system changes over the time- course. Dov Greenbaum, Mark Gerstein et. al. "Interrelating Different Types of  Genomic Data" Dept. of Biochemistry and Molecular Biology, Yale Univ. 2001 http://bioinfo.mbb.yale.edu/e-print/omes-genomeres/text.pdf.  Related terms: Omes & omics

functional genomics technologies: Conditional or tissue- specific gene expression in animal models is a major area of interest. Other increasingly popular methods of downregulating gene expression, in order to study function, include antisense, ribozyme, and zinc finger protein (ZFP) approaches. In addition, a limited number of companies have developed chemical- genetics methods. Include gene disruption, gene manipulation, gene shuffling, gene targeting, gene trapping, knockdowns, knockins, knockouts, mutagenesis, phage display, positional cloning, Post Translational Gene Silencing PTGS; RNA interference RNAi. 
Related terms chemical genetics, chemical genomics

functional homology: Sequence homology does not necessarily indicate functional homology. A number of labs are working with yeast and other non-human organisms to try to determine what the relationship between sequence and function might be, if there is any. 

functional profiling:  Linking genes and proteins to disease. 

gene function: The lack of a common language for gene functions is … proving to be a serious problem. E Pennisi "Seeking common language in a Tower of Babel" Science 286 (5439): 449 Oct. 15 1999

The nature of gene function was substantially specified by George W. Beadle and Edward Tatum [19] and Adrian M. Srb and Norman H. Horowitz [20] when they showed, using Neurospora crassa (Ascomycetes) as their experimental organism, that genes control the synthesis of enzymes, and in particular that each individual gene is responsible for the synthesis of one single enzyme. This one gene - one enzyme hypothesis was the culmination of the classical view of the gene. ... The classical concept of the gene started to break down as soon as it had been completely formulated.  Petter Portin in "The Origin, Development and Present Status of the Concept of the Gene: A Short Historical Account of the Discoveries" Univ. of Turku, Finland, Current Genomics, 2000   http://www.bentham.org/cg/sample/cg1-1/Portin.pdf  Related terms: biological function, function, genome function, molecular function; protein function Proteomics