August 22, 2016

Saccharomyces cerevisiae

Caenorhabditis_elegans

S. cerevisiae also knows as baker’s yeast or budding yeast has been used for making bread, beer and wine since the ancient times. In nature, yeast cells are found primarily on ripe fruits such as mature grapes and they need a vector (such as bees) to move from place to place.

S. cerevisiae cells are round to ovoid, 5–10 micrometers in diameter. They reproduce mainly by a cell division process known as budding (see videos below).  Their doubling time is 1.25-2 hours at 30°C or 86°C.  To grow, S. cerevisiae need certain sugars (glucose, maltose, etc), a nitrogen source (ammonia, urea etc), sources of phosphorus, sulphur and vitamins. They grow and survive in two forms either haploid (asexual) or diploid (sexual).  Due to this ability to grow them in these two forms as well as carry out homologous recombination, generation and maintenance of mutants is easy.

Its genome is approximately 12 million base pairs organized on 16 chromosomes  with very little non-coding DNA and codes for about 6,000 genes, yet for more than 20% of these genes the functions are still unknown.  Some of its significant contributions to biology are:  Discovery of cell cycle regulators, DNA damage and repair, signaling proteins, protein-processing enzymes, cancer and aging.

 

RNA in living cells

DNA in living cells

Dicentric chromosomes