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MCQ culture media part I mcq microbiology
Culture medium or growth medium may be a liquid or gel designed to support the expansion of microorganisms. There are differing types of media suitable for growing differing types of cells.
Here, we’ll discuss microbiological cultures used for growing microbes, like bacteria or yeast.
NUTRIENT BROTHS AND AGAR PLATES
These are the foremost common growth media, although specialized media are sometimes required for microorganism and cell culture growth. Some organisms, termed fastidious organisms, need specialized environments thanks to complex nutritional requirements. Viruses, for instance , are obligate intracellular parasites and need a growth medium containing living cells.
Many human microbial pathogens also require the utilization of human cells or cell lysates to grow on a media. The most common growth media nutrient broths (liquid nutrient medium) or LB medium (Lysogeny Broth) are liquid. These are often mixed with agar and poured into Petri dishes to solidify.
These agar plates provide a solid medium on which microbes could also be cultured. they continue to be solid, as only a few bacteria are ready to decompose agar. Many microbes also can be grown in liquid cultures comprised of liquid nutrient media without agar.
DEFINED VS UNDEFINED MEDIA
This is a crucial distinction between growth media types. an outlined medium will have known quantities of all ingredients. For microorganisms, it provides trace elements and vitamins required by the microbe and particularly an outlined carbon and nitrogen source.
Glucose or glycerol are often used as carbon sources, and ammonium salts or nitrates as inorganic nitrogen sources. An undefined medium has some complex ingredients, like yeast extract, which consists of a mix of the many , many chemical species in unknown proportions.
Undefined media are sometimes chosen supported price and sometimes by necessity – some microorganisms haven’t been cultured on defined media. There are many various sorts of media which will be wont to grow specific microbes, and even promote certain cellular processes; like wort, the medium which is that the growth media for the yeast that creates beer. Without wort in certain conditions, fermentation cannot occur and therefore the beer won’t contain alcohol or be carbonated (bubbly).
COMMON BROADLY-DEFINED CULTURE MEDIA
Nutrient media – A source of amino acids and nitrogen (e.g., beef, yeast extract). this is often an undefined medium because the aminoalkanoic acid source contains a spread of compounds with the precise composition being unknown. These media contain all the weather that the majority bacteria need for growth and are non-selective, in order that they are used for the overall cultivation and maintenance of bacteria kept in laboratory-culture collections.
Minimal media – Media that contains the minimum nutrients possible for colony growth, generally without the presence of amino acids, and are often employed by microbiologists and geneticists to grow “wild type” microorganisms. These media also can be wont to select for or against the expansion of specific microbes. Usually a good amount of data must be known about the microbe to work out its minimal media requirements.
Selective media – Used for the expansion of only selected microorganisms. for instance , if a microorganism is immune to a particular antibiotic, like ampicillin or tetracycline, then that antibiotic are often added to the medium so as to stop other cells, which don’t possess the resistance, from growing.
Differential media – Also referred to as indicator media, are wont to distinguish one microorganism type from another growing on an equivalent media. this sort of media uses the biochemical characteristics of a microorganism growing within the presence of specific nutrients or indicators (such as neutral red, phenol red, eosin y, or methylene blue) added to the medium to visibly indicate the defining characteristics of a microorganism. this sort of media is employed for the detection and identification of microorganisms.
These few samples of general media types provide some indication only; there are a myriad of various sorts of media which will be wont to grow and control microbes.
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