Sex linkage
The location of a gene on a sex chromosome, typically on the X chromosome.

Sex mosaic
See gynandromorph.

Sexed embryos
Embryos separated according to sex.

Sex factor
A bacterial episome (e.g., the F plasmid in E. coli) that enables the, cell to be a donor of genetic material. The sex factor may be propagated in the cytoplasm, or it may be integrated into the bacterial chromosome.

Sexual reproduction
The process where two cells (gametes) fuse to form one fertilized cell or zygote. cf asexual reproduction; gamete hybrid.

Shake culture
An agitated suspension in culture providing adequate aeration for cells in the liquid medium. Usually an Erlenmeyer flask containing the culture is attached to a horizontal or platform shaker, or agitated with a magnetic stirrer.

Shine Dalgarno sequence
A conserved sequence in prokaryotic mRNAs that is complementary to a sequence near the 5 terminus of the 16S ribosomal RNA and is involved in the initiation of translation. See ribosomal binding site.

Shoot tip graft; micrograft.
A shoot tip or rneristem tip is grafted onto a prepared seedling or
micropropagated rootstock in culture. Meristem tip grafting is mainly used for in vitro virus elimination with Citrus spp. and other plants.

Shoot tip; shoot apex
The terminal bud (0.1 1.0 mm) of a plant, which consists of the apical meristem (0.05 0.1 mm) and the immediate surrounding leaf primordial and developing leaves and adjacent stem tissue.