Which Of The Following Cleaning Methods Kills All Microorganisms On The Surface Of Anã¢â‚¬â€¹ Object?

Learning Objectives

• List the various types of microorganisms and depict their defining characteristics
• Give examples of different types of cellular and viral microorganisms and infectious agents
• Describe the similarities and differences between archaea and bacteria
• Provide an overview of the field of microbiology

Most microbes are unicellular and small enough that they crave artificial magnification to exist seen. However, there are some unicellular microbes that are visible to the naked eye, and some multicellular organisms that are microscopic. An object must mensurate near 100 micrometers (µm) to be visible without a microscope, but most microorganisms are many times smaller than that. For some perspective, consider that a typical animal prison cell measures roughly ten µm across but is still microscopic. Bacterial cells are typically about one µm, and viruses can be 10 times smaller than leaner (Figure 1). See Tabular array i for units of length used in microbiology.

Figure 1. The relative sizes of diverse microscopic and nonmicroscopic objects. Note that a typical virus measures about 100 nm, 10 times smaller than a typical bacterium (~i µm), which is at least 10 times smaller than a typical plant or animal prison cell (~10–100 µm). An object must mensurate about 100 µm to be visible without a microscope.

Tabular array 1. Units of Length Commonly Used in Microbiology
Metric Unit	Meaning of Prefix	Metric Equivalent
meter (k)	—	ane m = 100 m
decimeter (dm)	i/10	1 dm = 0.i grand = x−1 m
centimeter (cm)	1/100	1 cm = 0.01 thousand = ten−2 m
millimeter (mm)	one/m	1 mm = 0.001 thou = 10−3 m
micrometer (μm)	one/1,000,000	1 μm = 0.000001 one thousand = 10−6 1000
nanometer (nm)	1/1,000,000,000	i nm = 0.000000001 m = ten−nine m

Microorganisms differ from each other non but in size, only besides in structure, habitat, metabolism, and many other characteristics. While nosotros typically think of microorganisms as beingness unicellular, in that location are also many multicellular organisms that are too minor to be seen without a microscope. Some microbes, such as viruses, are even acellular (not composed of cells).

Microorganisms are found in each of the 3 domains of life: Archaea, Bacteria, and Eukarya. Microbes within the domains Bacteria and Archaea are all prokaryotes (their cells lack a nucleus), whereas microbes in the domain Eukarya are eukaryotes (their cells accept a nucleus). Some microorganisms, such every bit viruses, do not fall within any of the three domains of life. In this section, we volition briefly introduce each of the broad groups of microbes. Later capacity will get into greater depth about the diverse species inside each group.

Prokaryotic Microorganisms

Bacteria are found in nearly every habitat on earth, including within and on humans. Virtually bacteria are harmless or helpful, but some are pathogens, causing disease in humans and other animals. Bacteria are prokaryotic because their genetic cloth (DNA) is not housed within a truthful nucleus. Most bacteria accept jail cell walls that contain peptidoglycan.

Bacteria are oft described in terms of their full general shape. Common shapes include spherical (coccus), rod-shaped (bacillus), or curved (spirillum, spirochete, or vibrio). Effigy ii shows examples of these shapes.

Effigy 2. Common bacterial shapes. Note how coccobacillus is a combination of spherical (coccus) and rod-shaped (bacillus). (credit "Coccus": modification of work by Janice Haney Carr, Centers for Disease Control and Prevention; credit "Coccobacillus": modification of work by Janice Carr, Centers for Disease Control and Prevention; credit "Spirochete": Centers for Illness Control and Prevention)

They have a wide range of metabolic capabilities and tin grow in a multifariousness of environments, using different combinations of nutrients. Some bacteria are photosynthetic, such equally oxygenic blue-green alga and anoxygenic green sulfur and greenish nonsulfur leaner; these bacteria use free energy derived from sunlight, and ready carbon dioxide for growth. Other types of bacteria are nonphotosynthetic, obtaining their free energy from organic or inorganic compounds in their environs.

Archaea are also unicellular prokaryotic organisms. Archaea and bacteria accept unlike evolutionary histories, as well as significant differences in genetics, metabolic pathways, and the composition of their cell walls and membranes. Dissimilar near bacteria, archaeal cell walls exercise non incorporate peptidoglycan, but their cell walls are ofttimes composed of a like substance called pseudopeptidoglycan. Similar bacteria, archaea are found in nearly every habitat on world, fifty-fifty extreme environments that are very cold, very hot, very basic, or very acidic (Figure 3). Some archaea alive in the human torso, merely none have been shown to be human pathogens.

Effigy 3. Some archaea live in farthermost environments, such as the Morning Glory pool, a hot leap in Yellowstone National Park. The color differences in the puddle outcome from the different communities of microbes that are able to thrive at various water temperatures.

Think well-nigh It

• What are the ii main types of prokaryotic organisms?
• Proper name some of the defining characteristics of each type.

Eukaryotic Microorganisms

The domain Eukarya contains all eukaryotes, including uni- or multicellular eukaryotes such as protists, fungi, plants, and animals. The major defining characteristic of eukaryotes is that their cells contain a nucleus.

Protists

Protists are unicellular eukaryotes that are not plants, animals, or fungi. Algae and protozoa are examples of protists.

Effigy iv. Assorted diatoms, a kind of algae, live in annual sea ice in McMurdo Sound, Antarctica. Diatoms range in size from two μm to 200 μm and are visualized here using light microscopy. (credit: modification of work by National Oceanic and Atmospheric Administration)

Algae (singular: alga) are constitute-like protists that can exist either unicellular or multicellular (Figure 4). Their cells are surrounded by cell walls fabricated of cellulose, a type of sugar. Algae are photosynthetic organisms that extract energy from the sun and release oxygen and carbohydrates into their surround. Considering other organisms can use their waste products for energy, algae are important parts of many ecosystems. Many consumer products contain ingredients derived from algae, such as carrageenan or alginic acid, which are found in some brands of ice cream, salad dressing, beverages, lipstick, and toothpaste. A derivative of algae also plays a prominent role in the microbiology laboratory. Agar, a gel derived from algae, tin be mixed with various nutrients and used to grow microorganisms in a Petri dish. Algae are also being developed equally a possible source for biofuels.

Protozoa (singular: protozoan) are protists that brand up the backbone of many food webs past providing nutrients for other organisms. Protozoa are very various. Some protozoa motility with assist from pilus-similar structures called cilia or whip-similar structures called flagella. Others extend part of their cell membrane and cytoplasm to propel themselves forward. These cytoplasmic extensions are chosen pseudopods ("false feet"). Some protozoa are photosynthetic; others feed on organic material. Some are costless-living, whereas others are parasitic, but able to survive by extracting nutrients from a host organism. Near protozoa are harmless, just some are pathogens that can crusade disease in animals or humans (Figure five).

Figure 5. Giardia lamblia, an intestinal protozoan parasite that infects humans and other mammals, causing astringent diarrhea. (credit: modification of piece of work by Centers for Disease Command and Prevention)

Fungi

Fungi (atypical: mucus) are also eukaryotes. Some multicellular fungi, such as mushrooms, resemble plants, but they are actually quite different. Fungi are not photosynthetic, and their cell walls are normally made out of chitin rather than cellulose.

Figure 6. Candida albicans is a unicellular fungus, or yeast. It is the causative amanuensis of vaginal yeast infections as well as oral thrush, a yeast infection of the mouth that ordinarily afflicts infants. C. albicans has a morphology similar to that of coccus bacteria; withal, yeast is a eukaryotic organism (note the nuclei) and is much larger. (credit: modification of work by Centers for Disease Command and Prevention)

Unicellular fungi—yeasts—are included within the report of microbiology. There are more than m known species. Yeasts are found in many unlike environments, from the deep sea to the human bellybutton. Some yeasts have benign uses, such every bit causing bread to rise and beverages to ferment; but yeasts can also cause nutrient to spoil. Some even crusade diseases, such as vaginal yeast infections and oral thrush (Figure vi).

Other fungi of interest to microbiologists are multicellular organisms chosen molds. Molds are made upwardly of long filaments that form visible colonies (Figure 7). Molds are found in many different environments, from soil to rotting nutrient to dank bath corners. Molds play a critical role in the decomposition of dead plants and animals. Some molds can crusade allergies, and others produce disease-causing metabolites called mycotoxins. Molds have been used to brand pharmaceuticals, including penicillin, which is one of the most commonly prescribed antibiotics, and cyclosporine, used to prevent organ rejection following a transplant.

Figure 7. Large colonies of microscopic fungi can often exist observed with the naked eye, as seen on the surface of these moldy oranges.

Think nigh It

• Name two types of protists and two types of fungi.
• Proper name some of the defining characteristics of each type.

Helminths

Multicellular parasitic worms called helminths are not technically microorganisms, every bit most are large enough to see without a microscope. However, these worms fall within the field of microbiology because diseases caused past helminths involve microscopic eggs and larvae. I example of a helminth is the guinea worm, or Dracunculus medinensis, which causes dizziness, airsickness, diarrhea, and painful ulcers on the legs and feet when the worm works its way out of the skin (Figure 8). Infection typically occurs after a person drinks h2o containing water fleas infected by republic of guinea-worm larvae. In the mid-1980s, there were an estimated 3.5 meg cases of guinea-worm disease, but the disease has been largely eradicated. In 2014, there were only 126 cases reported, thank you to the coordinated efforts of the World Health Organization (WHO) and other groups committed to improvements in drinking water sanitation.^[one]

Figure 8. (a) The beef tapeworm, Taenia saginata, infects both cattle and humans. T. saginata eggs are microscopic (around 50 µm), but developed worms like the one shown hither can reach iv–10 grand, taking up residence in the digestive system. (b) An adult guinea worm, Dracunculus medinensis, is removed through a lesion in the patient's pare by winding it around a matchstick. (credit a, b: modification of work by Centers for Disease Control and Prevention)

Viruses

Viruses are acellular microorganisms, which means they are non equanimous of cells. Essentially, a virus consists of proteins and genetic textile—either Deoxyribonucleic acid or RNA, simply never both—that are inert outside of a host organism. However, by incorporating themselves into a host cell, viruses are able to co-opt the host's cellular mechanisms to multiply and infect other hosts.

Viruses can infect all types of cells, from human cells to the cells of other microorganisms. In humans, viruses are responsible for numerous diseases, from the mutual cold to deadly Ebola (Effigy 9). Nevertheless, many viruses exercise not cause disease.

Figure nine. (a) Members of the Coronavirus family can cause respiratory infections like the common common cold, astringent astute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS). Hither they are viewed under a transmission electron microscope (TEM). (b) Ebolavirus, a member of the Filovirus family, as visualized using a TEM. (credit a: modification of work by Centers for Disease Control and Prevention; credit b: modification of work by Thomas Due west. Geisbert)

Think near It

• Are helminths microorganisms? Explain why or why non.
• How are viruses different from other microorganisms?

Figure ten. A virologist samples eggs from this nest to be tested for the influenza A virus, which causes avian flu in birds. (credit: U.S. Fish and Wildlife Service)

Microbiology as a Field of Study

Microbiology is a wide term that encompasses the report of all unlike types of microorganisms. But in practice, microbiologists tend to specialize in one of several subfields. For example, bacteriology is the study of bacteria; mycology is the report of fungi; protozoology is the report of protozoa; parasitology is the written report of helminths and other parasites; and virology is the study of viruses (Figure 10).

Immunology, the study of the immune organisation, is oft included in the study of microbiology because host–pathogen interactions are central to our understanding of communicable diseases processes. Microbiologists can also specialize in certain areas of microbiology, such every bit clinical microbiology, environmental microbiology, applied microbiology, or food microbiology.

In this textbook, we are primarily concerned with clinical applications of microbiology, merely since the various subfields of microbiology are highly interrelated, we will often discuss applications that are not strictly clinical.

Bioethics in Microbiology

In the 1940s, the U.S. government was looking for a solution to a medical problem: the prevalence of sexually transmitted diseases (STDs) among soldiers. Several at present-infamous government-funded studies used human subjects to enquiry common STDs and treatments. In one such report, American researchers intentionally exposed more than 1300 human being subjects in Guatemala to syphilis, gonorrhea, and chancroid to determine the ability of penicillin and other antibiotics to combat these diseases. Subjects of the report included Guatemalan soldiers, prisoners, prostitutes, and psychiatric patients—none of whom were informed that they were taking part in the written report. Researchers exposed subjects to STDs by diverse methods, from facilitating intercourse with infected prostitutes to inoculating subjects with the bacteria known to cause the diseases. This latter method involved making a small wound on the subject's genitals or elsewhere on the body, and so putting bacteria directly into the wound. ^[2] In 2011, a U.South. government commission tasked with investigating the experiment revealed that only some of the subjects were treated with penicillin, and 83 subjects died by 1953, likely every bit a result of the study.^[three]

Unfortunately, this is one of many horrific examples of microbiology experiments that have violated basic ethical standards. Fifty-fifty if this study had led to a life-saving medical breakthrough (it did non), few would argue that its methods were ethically sound or morally justifiable. But not every instance is so clear cutting. Professionals working in clinical settings are frequently confronted with upstanding dilemmas, such as working with patients who decline a vaccine or life-saving blood transfusion. These are just two examples of life-and-decease decisions that may intersect with the religious and philosophical beliefs of both the patient and the wellness-intendance professional.

No affair how noble the goal, microbiology studies and clinical do must be guided by a sure ready of ethical principles. Studies must be done with integrity. Patients and inquiry subjects provide informed consent (not only agreeing to be treated or studied but demonstrating an understanding of the purpose of the study and any risks involved). Patients' rights must be respected. Procedures must exist approved by an institutional review lath. When working with patients, accurate record-keeping, honest communication, and confidentiality are paramount. Animals used for enquiry must be treated humanely, and all protocols must be approved past an institutional animal care and use committee. These are simply a few of the ethical principles explored in the Eye on Ethics boxes throughout this volume.

Clinical Focus: Cora, Resolution

This example concludes Cora'south story that started in What Our Ancestors Knew and A Systematic Approach.

Cora's CSF samples bear witness no signs of inflammation or infection, as would exist expected with a viral infection. However, there is a loftier concentration of a particular protein, 14-3-3 protein, in her CSF. An electroencephalogram (EEG) of her encephalon office is also aberrant. The EEG resembles that of a patient with a neurodegenerative disease like Alzheimer'southward or Huntington's, simply Cora's rapid cerebral pass up is not consequent with either of these. Instead, her doctor concludes that Cora has Creutzfeldt-Jakob disease (CJD), a type of transmissible spongiform encephalopathy (TSE).

CJD is an extremely rare disease, with merely about 300 cases in the United states of america each year. It is non caused by a bacterium, mucus, or virus, but rather by prions—which do non fit neatly into whatever particular category of microbe. Like viruses, prions are not found on the tree of life because they are acellular. Prions are extremely pocket-size, virtually one-tenth the size of a typical virus. They incorporate no genetic material and are equanimous solely of a type of abnormal protein.

CJD tin can have several unlike causes. It can be acquired through exposure to the brain or nervous-organization tissue of an infected person or brute. Consuming meat from an infected animal is 1 manner such exposure tin can occur. At that place have as well been rare cases of exposure to CJD through contact with contaminated surgical equipment^[iv][5] and from cornea and growth-hormone donors who unknowingly had CJD.^{[half-dozen][vii]} In rare cases, the disease results from a specific genetic mutation that can sometimes be hereditary. All the same, in approximately 85% of patients with CJD, the crusade of the illness is spontaneous (or desultory) and has no identifiable cause.^[viii] Based on her symptoms and their rapid progression, Cora is diagnosed with sporadic CJD.

Unfortunately for Cora, CJD is a fatal disease for which there is no approved treatment. Approximately ninety% of patients die within 1 year of diagnosis.^[9] Her doctors focus on limiting her pain and cognitive symptoms as her disease progresses. Eight months afterward, Cora dies. Her CJD diagnosis is confirmed with a brain dissection.

Key Concepts and Summary

• Microorganisms are very diverse and are found in all iii domains of life: Archaea, Bacteria, and Eukarya.
• Archaea and bacteria are classified every bit prokaryotes because they lack a cellular nucleus. Archaea differ from bacteria in evolutionary history, genetics, metabolic pathways, and cell wall and membrane composition.
• Archaea inhabit nearly every environment on world, but no archaea take been identified as human pathogens.
• Eukaryotes studied in microbiology include algae, protozoa, fungi, and helminths.
• Algae are plant-similar organisms that can be either unicellular or multicellular, and derive energy via photosynthesis.
• Protozoa are unicellular organisms with complex cell structures; well-nigh are motile.
• Microscopic fungi include molds and yeasts.
• Helminths are multicellular parasitic worms. They are included in the field of microbiology because their eggs and larvae are often microscopic.
• Viruses are acellular microorganisms that require a host to reproduce.
• The field of microbiology is extremely wide. Microbiologists typically specialize in one of many subfields, but all wellness professionals need a solid foundation in clinical microbiology.

Multiple Pick

Which of the following types of microorganisms is photosynthetic?

1. yeast
2. virus
3. helminth
4. algae

Testify Reply

Reply d. Algae is photosynthetic.

Which of the following is a prokaryotic microorganism?

1. helminth
2. protozoan
3. cyanobacterium
4. mold

Show Respond

Answer c. Cyanobacterium is a prokaryotic microorganism.

Which of the following is acellular?

1. virus
2. bacterium
3. fungus
4. protozoan

Prove Answer

Answer a. Viruses are acellular.

Which of the following is a type of fungal microorganism?

1. bacterium
2. protozoan
3. alga
4. yeast

Testify Reply

Answer d. Yeast is a blazon of fungal microorganism.

Which of the following is not a subfield of microbiology?

1. bacteriology
2. botany
3. clinical microbiology
4. virology

Show Respond

Respond b. Botany is non a subfield of microbiology.

Fill in the Bare

A ________ is a illness-causing microorganism.

Evidence Respond

A pathogen is a disease-causing microorganism.

Multicellular parasitic worms studied past microbiologists are called ___________.

Show Reply

Multicellular parasitic worms studied by microbiologists are called helminths.

The study of viruses is ___________.

Show Answer

The study of viruses is virology.

The cells of prokaryotic organisms lack a _______.

Prove Answer

The cells of prokaryotic organisms lack a nucleus.

Think nearly It

1. Depict the differences between bacteria and archaea.
2. Name three structures that various protozoa use for locomotion.
3. Describe the actual and relative sizes of a virus, a bacterium, and a plant or fauna cell.
4. Contrast the behavior of a virus outside versus within a cell.
5. Where would a virus, bacterium, fauna cell, and a prion vest on this chart?

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Source: https://courses.lumenlearning.com/microbiology/chapter/types-of-microorganisms/

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