There are many yeasts diluted in soil, and saccharomyces is a common eukaryotic receptor cell in gene cloning experiments, so it is as convenient to cultivate yeasts as Escherichia coli. There are many kinds of yeast cloning vectors. Yeast also has plasmids. This 2μm long plasmid is called 2μm plasmid, which is about 6 3bp. This plasmid exists outside the chromosome in the nucleus for at least a period of time, and a shuttle plasmid that can shuttle between bacteria and yeast cells can be constructed by using the 2μm plasmid and the plasmid in Escherichia coli. Yeast cloning vectors are all constructed on this basis. [1]
Yeast is a unicellular fungus, not a unit of phylogenetic classification. A tiny single-celled microorganism invisible to the naked eye, which can ferment sugar into alcohol and carbon dioxide, is distributed in the whole nature. It is a typical heterotrophic and facultative anaerobic microorganism, which can survive in both aerobic and anaerobic conditions and is a natural starter.
Generally, it refers to all kinds of single-celled fungi that can ferment sugars, which can be used for brewing production, and can also be pathogenic bacteria-model organisms for genetic engineering and cell cycle research. Yeast is the earliest microorganism used in the history of human civilization. There are more than 1 kinds of yeasts. According to their ability to produce spores (ascospores and basidiospores), yeasts can be divided into three types: the strains that form spores belong to ascomycetes and basidiomycetes. Those that do not form spores but propagate mainly through budding are called incomplete fungi, or "pseudoyeasts" (yeast-like).
it is known that very few yeasts are classified into ascomycetes. Yeast is widely distributed in nature, mainly growing in acidic, humid and sugary environment. In February, 218, the precise customized synthesis of yeast long chromosomes won the Top Ten Scientific Progress of China in 217 by the Ministry of Science and Technology. [2]
Chinese name
Yeast
alias
yeast
Latin scientific name
yeast
boundary
fungi
ascomycetes
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Explore. Fungi that can ferment organic matter are called "yeast". Also known as "yeast" and "brewing mother".
zhuyin jiàomǔ
short for yeast.
Introduction of Yeast
Yeast is a unicellular fungus, which can survive in both aerobic and anaerobic environments and belongs to facultative anaerobic bacteria.
***3 micrographs of yeast cell structure
cell morphology
The width (diameter) of yeast cells is about 2~6μm, and the length is 5~3μm, while others are longer. The individual shapes are spherical, oval, elliptical, columnar and sausage-shaped.
physiological characteristics
yeast is a single-celled microorganism. It belongs to fungi of higher microorganisms. There are nuclei, cell membranes, cell walls, mitochondria, the same enzymes and metabolic pathways. Yeast is harmless and easy to grow. It exists in air, soil, water and animals. You can live with or without oxygen.
Yeast is a facultative anaerobic organism, and no obligate anaerobic yeast is found. In the absence of oxygen, fermented yeast obtains energy by converting sugar into carbon dioxide and ethanol (commonly known as alcohol).
most yeasts can be isolated in environments rich in sugars, such as some fruits (grapes, apples, peaches, etc.) or plant secretions (such as cactus juice). Some yeasts live in insects. Yeast is a single-celled eukaryotic microorganism, which is usually spherical, oval, sausage-shaped, oval, lemon-shaped or lotus-node shaped, which is much larger than the single-celled individual of bacteria, generally 1 ~ 5 or 5 ~ 2 microns. Yeast can't swim without flagella. Yeast has a typical eukaryotic cell structure, including cell wall, cell membrane, nucleus, cytoplasm, vacuole, mitochondria, etc., and some also have microsomes.
the genetic material composition of yeast: nuclear DNA, mitochondrial DNA and special plasmid DNA.
The colony characteristics of most yeasts are similar to those of bacteria, but larger and thicker than bacterial colonies. The colony surface is smooth, moist and sticky, which is easy to stir up. The colony texture is uniform, and the colors on the front and back, the edges and the center are uniform. Most colonies are milky white, a few are red and some are black.
reproductive mode
the reproductive mode of yeast can be divided into two categories: asexual reproduction and sexual reproduction.
asexual reproduction includes: budding, splitting and budding.
sexual reproduction mode: ascospores.
budding: this is the main way for yeast to reproduce asexually. Mature yeast cells first grow a small bud, which grows to a certain extent and continues to grow away from the mother cell, and then forms a new individual. There are buds at one end, buds at two ends, buds at three ends and buds at many ends.
fission: a few kinds of yeast, like bacteria, reproduce by transverse cell division.
bud splitting: the mother cell always shoots at one end, and forms a diaphragm at the bud base, and the daughter cell is bottle-shaped. This way is rare.
Ascomycetes: When the nutritional status is not good, some yeasts that can have sexual reproduction will form spores (generally four), and then germinate when the conditions are suitable. Some yeasts, such as Candida, cannot reproduce sexually.
Life history
Schematic diagram
The life history of various yeasts can be divided into three types: 1. Haploid type 2. Diploid type 3. Monodiploid type
1. Monodiploid type
Monodiploid type is represented by beer yeast
Features: both haploid vegetative cells and diploid vegetative cells can germinate. Vegetation can exist in haploid or diploid form; Sexual reproduction under certain conditions. Haploid and diploid stages are equally important, forming the world.