The invention relates to novel elongase genes with the sequences stated in sequence SEQ ID NO:1, SEQ ID NO: 3, SEQ ID NO: 5 and SEQ ID NO: 7 or their homologs, derivatives or analogs, to a gene construct comprising this gene or its homologs, derivatives and analogs, and to its use. The invention also relates to vectors or transgenic organisms comprising an elongase gene with the sequence SEQ ID NO:1, SEQ ID NO: 3, SEQ ID NO: 5 and SEQ ID NO: 7 or its homologs, derivatives and analogs. The invention furthermore relates to the use of the elongase gene sequences alone or in combination with further elongases and/or further fatty acid biosynthesis genes. The present invention relates to a novel elongase gene with the sequence SEQ ID NO:1 or its homologs, derivatives and analogs. Furthermore, the invention relates to a process for the preparation of polyunsaturated fatty acids and to a process for introducing DNA into organisms which produce large amounts of oils and, in particular, oils with a high content of unsaturated fatty acids. Moreover, the invention relates to an oil and/or a fatty acid preparation with a higher content of polyunsaturated fatty acids with at least two double bonds and/or a triacylglycerol preparation with a higher content of polyunsaturated fatty acids with at least two double bonds.