Yeasts

Yeasts are a group based on similar ____ ____, rather than similar genetics or morphologies

Growth habits

Characteristics of yeasts

Single-celled eukaryotes that mainly reproduce by budding or fission

A yeast colony closely resembles a

bacterial colony

Sometimes yeasts are found in a mycelial form, called

dimorphic form

Do yeasts reproduce sexually, aseuxually, or both?

Both

Two forms of asexual yeast reproduction are:

Budding
Fission

Budding: Daughter cell is _______ than parent

Smaller

Fission: Daughter cell is _______ as parent

Same size

How do yeasts reproduce sexually?

Ascospores or basidiospores

Saccharomyces is a budding or fission yeast

Budding

What yeast is involved in alcohol fermentation

Saccharomyces (sugar fungus)

Alcoholic fermentation is done under aerobic or anaerobic conditions?

Anaerobic

Reactants of ethanol fermentation are

Sugars and H2O

Products of ethanol fermentation are

Ethyl alcohol and CO2

To complete fermentation, one must use a strain of yeast that is

tolerant to high alcohol levels

What role does wild yeast play in wine production?

Already found on the grapes/in juice, starts the fermentation

What role does wine yeast (added yeast) play in wine production?

Introduced b/c it is more tolerant to alcohol and takes the fermentation to completion

What is the extra step in sparkling wine production?

Second fermentation once bottle is capped, CO2 production makes it sparkling

How is sparkling wine accomplished for cheap sparkling wines?

CO2 is injected into the still wine, no second fermentation

What is the name of spent yeast from wine production?

Lees

What is Noble rot?

A fungus that removes H2O from grapes, making it sweeter

What is the fungus involved in noble rot?

Botrytis cinerea

What type of wine is produced from noble rot?

Botrytised wine

How is ice wine made?

Freezing grapes to form ice shards and remove H2O from grape

What are the 5 ways beer production is different from wine making?

beer is sterilized

different strains/species of yeast used

sugar source is malted barley

additives (hops) added to beer

water added to beer

What are hops ahd how do they contribute to beer

Additive to beer that makes it bitter and taste better

What extra fungus, besides yeast, is added to sake?

Aspergillus oryzae

What role does A. oryzae play in sake production?

Turns rice into sugar, which can then be fermented to sake

Bread yeast does a good job at forming lots of what product

CO2

What is the sugar source in bread making?

Dough

Where does ethyl alcohol go when making bread?

evaporates off in the oven

What causes dough to rise in bread?

CO2

What are yeast flakes?

Deactivated yeast

What do yeast flakes/vegemite/marmite contain that makes it nutritious, especially for vegans?

B-vitamin complex / proteins

What is vegemite/marmite?

Leftover brewery yeast extract

How is kefir made?

Fermenting milk with yeast and bacteria

Which yeast is often used in research?

Sacchromyces cerevisiae

What accomplishments have been made with S. cerevisiae ?

Several Nobel peace prizes in fields of bcmb, cbio, and genetics