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Saccharomyces Cerevisiae - aka yeast

learn lots about yeast on the SGD wiki lots of tools are available at SGD ->

  • General Yeast info

  • Growth media

Yeast need Carbon Nitrogen Phosphate Oxygen and Hydrogen

Oxygen from the air - note that S.cerevisiae are commonly stated to be faculative anerobes but that has been disputed. "It only grows for a few generations without air and does not obtain much energy from respiration during its aerobic growth on sugars" (see  They need oxygen for synthesis of egersterol (sort of the yeast version of cholesterol).

C N P H from growth media

There are two main types of growth media - "rich" or YPD (or really yeast extract and peptone based) 

YEP - 1% yeast extract, 2% bacto peptone, 

Yeast extract is what is sounds like, the extract of yeast thus it contains many nutrients yeast would normally use to grow

Peptone - is an enzymatic digest of animal protein (thus is a source of Nitrogen, at least partially via amino acids e.g., glutamate, glutamine, proline)

to make solid media, 2% agar is added

Agar - "is a gelatinous substance derived by boiling a polysaccharide in red algae, where it accumulates in the cell walls of agarophyte and serves as the primary structural support for the algae's cell walls" (from wikipedia)

see more specifics of media here, particularly "Synthetic media"

Commonly used media terms / abbreviations

YPD (aka YEPD)- yeast extract, peptone, and 2% Dextrose (aka glucose), Carbon source

YPG - YEP + 3% glycerol - glycerol is three carbons each with a OH attached

typcially synthetic media is made lacking one or more amino acids and names minus aminoacid  (e.g., -HIS media does not have histidineadded) or nucleobase (e.g. -URA doesnt contain uracil).  This is used for selection, so that yeast must have exogenously obtained (e.g., via plasmid or linear dna you introduce)  a biosynthesis gene that the yeast have been engineered to lack For BY4742/4741 they lack the entire URA3 gene, LEU2 gene, and lack a chunk of the HIS3 gene) so BY cannot grow on media lacking uracil, histidine or leucine.

About BY strain

BY4743 - diploid, ura3delta0 leu2delta0 his3delta1 

BY4742 - Matα MET15+ lys2- ura3 leu2 his3 haploid

BY4741 MatA LYS2+ MET15- ura3 leu2 his3 haploid

This strain is derived from S288C, which is the strain you will commonly see on the SGD website

Genotype: S288C SUC2 gal2 mal mel flo1 flo8-1 hap1 ho (from SGD)

gal2 - Galactose permease, required for utilization of galactose; also able to transport glucose 

mal ?

mel ?

flo1 - lectin-like protein involved in flocculation; cell wall protein that binds mannose chains on the surface of other cells, confers floc-forming ability (probably decreases aggregation of the yeast)

flo8-1 Transcription factor required for flocculation, diploid filamentous growth, and haploid invasive growth; genome reference strain S288C and most laboratory strains have a nonsense mutation in this gene

hap1 - zinc finger transcription factor involved in the complex regulation of gene expression in response to levels of heme and oxygen; the S288C sequence differs from other strain backgrounds due to a Ty1 insertion in the carboxy terminus' - although it is partially functional, ('this mutation is not by design)

ho - 'HO endonuclease required for mating type switching (keeps MATA cells A and alpha cells alpha)

BY4743 - MATa/α his3Δ1/his3Δ1 leu2Δ0/leu2Δ0 LYS2/lys2Δ0 met15Δ0/MET15 ura3Δ0/ura3Δ0

mip1 variant - mitochondrial DNA polymerase (this mutation is not by design)

notes about gene deletions:

ura3 deleted and ~295bp upstream? ~75bp downstream; *need to reverify this*

his3 only small region deleted, illustrated below


his3 delta region shown