Producing polyunsaturated fatty acids (I) comprises introducing nucleic acid sequences coding for delta 9 elongase or delta 6 desaturase, delta 8 desaturase or delta 6 elongase, delta 5 desaturase, delta 5 elongase and delta 4 desaturase activity into an organism to produce a transgenic organism whose total lipids include at least 1 wt.% (I). Producing polyunsaturated fatty acids of formula (I) comprises introducing nucleic acid sequences coding for delta 9 elongase or delta 6 desaturase, delta 8 desaturase or delta 6 elongase, delta 5 desaturase, delta 5 elongase and delta 4 desaturase activity into an organism to produce a transgenic organism whose total lipids include at least 1 wt.% of formula (I). [Image] R 1>；OH, coenzyme A (thioester), lysophosphatidyl choline, lysophosphatidyl ethanolamine, lysophosphatidyl glycerol, lysophosphatidyl serine, lysophosphatidyl inositol, sphingobase or OCH 2CH(OR 3>；)CH 2OR 2>；； R 2>；H, lysophosphatidyl choline, lysophosphatidyl ethanolamine, lysophosphatidyl glycerol, lysophosphatidyl serine, lysophosphatidyl inositol, (un)saturated 2-24C alkylcarbonyl or CO(CH 2) n(CH=CHCH 2) m(CH 2) pCH 3； R 3>；H, (un)saturated 2-24C alkylcarbonyl or CO(CH 2) n(CH=CHCH 2) m(CH 2) pCH 3； n : 2-9； m : 2-6； p : 0 or 3. Independent claims are also included for: (1) oils, lipids or fatty acids produced as above； (2) oil, lipid or fatty acid composition that comprises polyunsaturated fatty acids produced as above and is derived from transgenic plants； (3) isolated nucleic acid sequence coding for a delta 5 elongase polypeptide having one of 6 amino acid sequences given in the specification； (4) isolated nucleic acid sequence that codes for a delta 6 elongase polypeptide and has one of 4 nucleotide sequences given in the specification； (5) isolated nucleic acid sequence that codes for a omega 3 desaturase polypeptide and has one of 2 nucleotide sequences given in the specification； (6) isolated nucleic acid sequence that codes for a delta
