History & Scope : Types of Micro-organisms

History & Scope of Microbiology : 

                                  

Louis Pasteur, one of the greatest scientists of the nineteenth century,

maintained that “Science knows no country, because knowledge belongs

to humanity, and is a torch which illuminates the world.”

                                

                                                            Sir Louis Pasteur

Domain which play unique & vital role in life where it belongs to life and shows the core knowledge of any living thing and its positions and place also tell about the situation about the life in this chapter we will go through the study of life and different aspects of its shadow in the day today life and its presence which varies from the whole new world of possibilities to live and grow the other one :)

The Domain of Life _

                                              

Archaea :

                    The domain of life that contains procaryotic cells with

                    cell walls that lack peptidoglycan; they have unique lipids in

                    their membranes and archaeal rRNA (among many differences).

Bacteria :

                   The domain of life that contains procaryotic cells with

                   cell walls that contain the structural molecule peptidoglycan;

                   they have bacterial rRNA.

Eucarya :

                    The domain of life that features organisms made of

                    cells that have a membrane-delimited nucleus and differ in

                    many other ways from procaryotic cells; includes protists,

                    fungi, plants, and animals.

Fungi    :

                   A diverse group of microorganisms that range from

                   unicellular forms (yeasts) to multicellular molds and

                    mushrooms.

Types of Microorganisms :

 

Bacteria : 

Bacteria (singular: bacterium) are relatively simple, single-celled

(Unicellular) organisms. Because their genetic material is not

enclosed in a special nuclear membrane, bacterial cells are called

prokaryotes from Greek words meaning prenucleus.

Prokaryotes include both bacteria and archaea

Bacterial cells generally appear in one of several shapes. Bacillus

(rodlike) coccus (spherical or ovoid), and spiral (corkscrew or curved)

are among the most common shapes, but some bacteria are starshaped

or square.

Individual bacteria may form pairs, chains, clusters, or other

groupings; such formations are usually characteristic of a particular

genus or species of bacteria.

Bacteria are enclosed in cell walls that are largely composed

of a carbohydrate and protein complex called peptidoglycan. (By

contrast, cellulose is the main substance of plant and algal cell

walls.) Bacteria generally reproduce by dividing into two equal

cells; this process is called binary fission. For nutrition, most

bacteria use organic chemicals, which in nature can be derived

from either dead or living organisms. Some bacteria can manufacture

their own food by photosynthesis, and some can derive

nutrition from inorganic substances. Many bacteria can “swim”

by using moving appendages called flagella. (For a complete discussion

of bacteria.

Archaea : 

Like bacteria, archaea consist of prokaryotic cells,

but if they have cell walls, the walls lack peptidoglycan. Archaea,

often found in extreme environments, are divided into three

main groups. The methanogens produce methane as a waste

product from respiration. The extreme halophiles (halo = salt;

philic = loving) live in extremely salty environments such as the

Great Salt Lake and the Dead Sea. The extreme thermophiles

(therm = heat) live in hot sulfurous water, such as hot springs

at Yellowstone National Park. Archaea are not known to cause

disease in humans.

Fungi :

 

Fungi (singular: fungus) are eukaryotes organisms

whose cells have a distinct nucleus containing the cell’s genetic

material (DNA), surrounded by a special envelope called

the nuclear membrane. Organisms in the Kingdom Fungi may

be unicellular or multicellular Large

multicellular fungi, such as mushrooms, may look somewhat like

plants, but unlike most plants, fungi cannot carry out photosynthesis.

True fungi have cell walls composed primarily of a substance

called chitin. The unicellular forms of fungi, yeasts, are oval

microorganisms that are larger than bacteria. The most typical

fungi are molds.Molds form visible masses called mycelia,

which are composed of long filaments (hyphae) that branch

and intertwine. The cottony growths sometimes found on bread

and fruit are mold mycelia. Fungi can reproduce sexually or asexually.

They obtain nourishment by absorbing solutions of organic

material from their environment—whether soil, seawater, freshwater,

or an animal or plant host. Organisms called slime mold shave characteristics of both fungi and amebae.

Protozoa :

 

Protozoa (singular: protozoan) are unicellular eukaryotic microbes

Protozoa move by pseudopods,

flagella, or cilia. Amebae move by using extensions

of their cytoplasm called pseudopods (false feet). Other protozoa

have long flagella or numerous shorter appendages for locomotion

called cilia. Protozoa have a variety of shapes and live either as

free entities or as parasites (organisms that derive nutrients from

living hosts) that absorb or ingest organic compounds from their

environment. Some protozoa, such as Euglena are

photosynthetic. They use light as a source of energy and carbon dioxide as their chief source of carbon to produce sugars. Protozoa

can reproduce sexually or asexually.

Algae :

 

Algae (singular: alga) are photosynthetic eukaryotes with a wide

variety of shapes and both sexual and asexual reproductive forms

The algae of interest to microbiologists are usually

unicellular .The cell walls of many algae are composed of a carbohydrate called cellulose. Algae are

abundant in freshwater and saltwater, in soil, and in association

with plants. As photosynthesizers, algae need light, water, and

carbon dioxide for food production and growth, but they do not

generally require organic compounds from the environment. As

a result of photosynthesis, algae produce oxygen and carbohydrates

that are then utilized by other organisms, including animals.

Thus, they play an important role in the balance of nature.

Viruses :

 

Viruses  are very different from the other microbial

groups mentioned here. They are so small that most can be seen

only with an electron microscope, and they are acellular(not

cellular). Structurally very simple, a virus particle contains a

core made of only one type of nucleic acid, either DNA or RNA.

This core is surrounded by a protein coat, which is sometimes

encased by a lipid membrane called an envelope. All living cells

have RNA and DNA, can carry out chemical reactions, and can

reproduce as self-sufficient units. Viruses can reproduce only by

using the cellular machinery of other organisms. Thus, on the

one hand, viruses are considered to be living only when they

multiply within host cells they infect. In this sense, viruses are

parasites of other forms of life. On the other hand, viruses are

not considered to be living because they are inert outside living

hosts. 

for the further in very exploring sense we will discuss again another topics Stay tuned !

 

 

Sir Antonio Van Leeuwenhoek observation "animalecule"

 

Leeuwenhoek Microscope

 Leeuwenhoek Observations