NOVELTY - A nucleic acid comprising an expression cassette, the expression cassette comprises, operably linked in a 5' to 3' direction: (a) a promoter operable in filamentous fungi; (b) a non-fungal 5' untranslated region (5'-UTR) operable in filamentous fungi; (c) a first polypeptide coding sequence comprising a start codon and a stop codon; and (d) a 3' untranslated region (3'-UTR), is new.    USE - The nucleic acid is useful or producing recombinant polypeptide, secreted polypeptide, cellulase composition, and fermentation product; and for saccharifying biomass (all claimed).    ADVANTAGE - Expression systems that are economically viable and that promote efficient translation in large scale commercial fermentations, are provided. The non-fungal 5' UTRs can enable efficient translation of downstream coding sequences, can improve yield of polypeptides produced from transcripts bearing these sequences, and can broaden the choices available for engineering expression constructs for production of heterologous proteins in filamentous fungal hosts.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a vector comprising the nucleic acid;    (2) a filamentous fungal cell comprising a recombinant expression cassette, where the expression cassette comprises: (a) promoter operable in filamentous fungi; and (b) non-fungal 5' UTR operable a first polypeptide coding sequence comprising a start codon and a stop 3' UTR;    (3) a method for producing a recombinant polypeptide, comprising culturing the filamentous fungal cell under conditions that result in expression of the first polypeptide;    (4) a method for producing a secreted polypeptide, comprising culturing the filamentous fungal cell under conditions that result in expression and secretion of the first polypeptide;    (5) a method for producing a cellulase composition, comprising culturing the filamentous fungal cell under conditions that result in expression of the first protein;    (6) a method for saccharifying biomass, comprising: (a) producing a cellulase composition by the method above; and (b) treating biomass with the cellulase composition, thus saccharifying the biomass; and    (7) a method for producing a fermentation product, comprising: (a) producing a cellulase composition by the method above; (b) treating biomass with the cellulase composition, thus producing fermentable sugars; and (c) culturing a fermenting microorganism in the presence of the fermentable sugars produced in step (b) under fermentation conditions, thus producing a fermentation product.