Yeast Biology

General Biology Living Organism Classification- Taxonomy 3 Domain System 5 Kingdom System

What is a CELL? Cells are the “basic unit of life” Cells can live on their own, reproduce and do all the processes living things do Single cell organisms, like: bacteria and yeast Multicellular organisms, like: plants and animals

What is a CELL? What are the 3 main parts of a cell? 1. Cell membrane 2. Nucleus 3. Cytoplasm

What is a CELL? Cell (plasma) membrane The cell wrapper made of mostly lipids (fats) This wrapper has control over many important functions, including what goes in and out of the cell

What is a CELL? Nucleus Primarily made of DNA/chromosomes/genes-- the so-called “genetic material” The genetic material is essentially the ‘recipe’ to make other cell parts, cell products (like ethanol in yeasts), and entire cells, for that matter nucleus

What is a CELL? Cytoplasm The water part of the cell Also contains organelles -- structures that have specific functions The fermentation chemical reactions occur our here

What is a CELL? Cytoplasm Organelles -- structures that have specific functions Rough endoplasmic reticulum (ER): site of protein production. Smooth ER: site of lipid or fat production. Mitochondrion: site of energy production. Vacuoles: sacks of any kind of product or water.

What is a CELL? Smooth ER Rough ER Mitochondrion

What is a CELL? Cell Wall An additional structure, external to the cell membrane Most bacteria have cell walls All yeast have cell walls. (Animals like us and dogs, do not have cell walls.) Cell walls give the cell extra protection and structure- like an external skeletal system. Chemicals can go in and out of cell walls.

Asexual Sexual Cell Reproduction- 2 types Only 1 Takes 2 Goal Fast Simple However, . . . Sexual Takes 2 More lengthy in time More complicated More potential problems Goal However, . . .

Sexual Asexual Cell Reproduction- 2 types Plants Bacteria Fungi Animals Some Protists Asexual Bacteria Brewing/Distilling Yeast Some Protists

What is a yeast cell? Single cell organism Member of Fungus Kingdom Some yeasts cause human/animal diseases Yeasts are used to ferment alcohol: wine, liquor and BEER! Yeast can also be used to bake– the CO2 causes bread to rise

What is a yeast cell?

The 2 basic brewing yeast types: Ale Yeasts and Lager Yeasts Ale yeast species is Sacchromyces cerevisiae Lager yeast species is Sacchromyces pastorianus Sacchromyces, literally means, “sugar fungus”

The 2 basic brewing yeast types: Ale Yeasts and Lager Yeasts Ale yeast species is Sacchromyces cerevisiae Classic, ‘natural’ brewing yeast Ferment at higher temperatures Produce more complex flavor compounds -esters -phenols Lager yeast species is Sacchromyces pastorianus Developed in lab at Carlsberg Brewery in 1883 (Saccharomyces carlsbergensis)  Ferment at lower temperatures Produce less complex flavor compounds

Yeast REPRODUCTION Brewing yeast reproduce asexually: they essentially make an exact copy of themselves…called BUDDING Yeast will start reproducing after being ‘pitched’ into the wort. (there is not enough yeast to eat up all the s-sugars) They need to reproduce so they can eat up all the simple sugars to produce as much ethanol as possible Bud (new ‘baby’ yeast cell) Parent yeast cell

WHY WE ADD O2 BEFORE FERMENTING BREWING CHEMISTRY C6H1206 → C2H5O + CO2 ENERGY FOR REPRODUCTION

WHEN (EXACTLY) DO WE ADD O2 BEFORE FERMENTING? BREWING CHEMISTRY TO CHILLED WORT