More About Yeast

Yeast belong to a group of organisms known as fungi. Some types of yeast include wet yeast, instant yeast and active dry yeast. Most yeasts are unicellular, although yeasts may become multicellular through the formation of a string of connected budding cells known as pseudohyphae, or true hyphae as seen in most moulds. They do not contain chlorophyll, hence unable to make their own food. They feed on sugar from a variety of sources. These sugars are then broken down into carbon dioxide and water. Only under anaerobic conditions, such as alcoholic fermentation, is yeast able to produce ethanol and carbon dioxide. (Are you able to write the word equation?)

Yeast, is used in baking as a leavening agent, where it converts the fermentable sugars present in the dough into carbon dioxide. This causes the dough to expand or rise as the carbon dioxide forms pockets or bubbles. When the dough is baked, it "sets" and the pockets remain, giving the baked product a soft and spongy texture. The primary function of yeast is to supply carbon dioxide gas which inflates the dough during proof and the early stages of baking.

The use of potatoes, water from potato boiling, eggs, or sugar in a bread dough accelerates the growth of yeasts. Salt and fats such as butter slow down yeast growth.

Where else is yeast used? In Marmite! And also, beverages such as wine(sake = japanese rice wine), beer, or distilled spirits all use yeast at some stage of their production!

Queries on Twins

Hi Kenneth Neo, identical twins, formed when one fertilized egg splits, are the only people in the world with identical DNA. Fraternal twins, on the other hand, are formed when two different eggs are fertilized. Genetically speaking, fraternal twins are no closer than normal siblings, sharing only about 50% of their genes.

Although identical twins have the same genotype, or DNA, they have different phenotypes, meaning that the same DNA is expressed in different ways.

Traits determined by phenotype, such as fingerprints and physical appearance, are the result of "the interaction of the individual's genes and the developmental environment in the uterus. Thus, a DNA test can't determine the difference between identical twins, while a simple fingerprint can. You can read more on Twins here.

Valerie, you can find your answers here. Click on more links at the bottom of the page!