DH140 LO1A: Classify infectious agents and their characteristics.

What is the definition of Microbiology?

The study of living things too small to be seen without magnification.

What are microorganisms or microbes commonly called, even though not all of them cause disease?

“Germs, viruses, agents…”.

What are the five major microorganisms whose characteristics are examined in the learning objectives?

Bacteria, algae, protozoa, fungi, and viruses.

What is Bacteriology?

The science of bacteria, the causative agents of a member of infectious diseases.

What is Virology?

The science of viruses, non-cellular living systems, capable of causing infectious diseases in man.

What is Immunology concerned with?

Mechanisms of body protection against pathogenic microorganisms and foreign cells and substances.

What is Mycology?

The study of fungi pathogenic for man.

What is Protozoology?

The branch of microbiology that deals with pathogenic unicellular animal organisms.

Name three general benefits that microorganisms provide.

Maintain balance of environment (microbial ecology), basis of food chain, and aid in digestion and synthesis of vitamins.

What is Gene therapy?

Inserting a missing gene or replacing a defective one in human cells.

Who was Robert Hooke (1665)?

The first person to use a microscope for academic study and proposed the Cell Theory.

What is the Cell Theory proposed by Robert Hooke?

All living things are composed of cells.

What concept suggested that some forms of life could arise spontaneously from non-living matter?

Spontaneous generation.

How did Redi’s Experiments (1668) disprove the spontaneous generation (SG) theory?

Redi showed that when decaying meat was kept isolated from flies, maggots never developed, but meat exposed to flies was soon infested.

Who was Antoni van Leeuwenhoek?

He first observed “animacules” (bacteria, yeast, protozoa) when he observed tooth scrapings and gutter water under a simple microscope.

Who was the first person to recognize the existence of tiny living particles that cause "catching" (contagious) disease by spread through direct/indirect contact?

Girolamo Fracastoro.

How did Louis Pasteur's "swan-necked flasks" experiment support the theory that microbes come from the air, not spontaneous generation?

When the flasks remained upright, no microbial growth appeared; when the flask was tilted, dust from the bend in the neck seeped back into the flask and made the infusion cloudy with microbes within a day.

Which two individuals are noted for emphasizing the importance of hand-washing?

Ignaz Semmelweis and Oliver Holmes.

Who established the first aseptic technique in surgery (in the UK, 1867) due to concerns about post-operative infections?

Joseph Lister.

What four advancements are credited to Koch, aside from the Postulates?

Simple staining techniques, use of steam to sterilize media, use of Petri dishes, and recognizing bacteria as distinct species.

What are the first two of Koch’s Postulates (1876)?

1. The specific causative agent must be found in every case of the disease. 2. The disease organism must be isolated from the lesions of the infected case and maintained in pure culture.

What are the last two of Koch’s Postulates?

3. The pure culture, inoculated into a susceptible or experimental animal, should produce the symptoms of the disease. 4. The same bacterium should be re-isolated in pure culture from the intentionally infected animal.

Who is known as the “Father of ORAL MICROBIOLOGY” and what was his theory of caries?

Willoughby D. Miller; his Chemo-parasitic theory held that caries is caused by acids produced by oral bacteria following fermentation of sugars.

Who is credited with early work on Immunization?

Edward Jenner.

What were the three most significant events in the early history of microbiology?

The development of microscopes, bacterial staining procedures, and techniques for microbial lab culture.

What are nanobacteria?

Microorganisms that are a hundred times smaller than common bacteria.

What are three types of microscopes used for microbial examination listed in the sources?

Light microscope, Transmission Electron microscope, and Scanning Electron microscope.

Define disinfection and provide an example.

Disinfection does not destroy all life forms, but it does free surfaces from infectious materials (e.g., EPA-approved disposable wipes are used in most health care settings).

Define sterilization and provide an example.

Sterilization is defined as destruction of all life forms (e.g., using an autoclave for heat sterilization to sterilize instruments).

What was the cause of the Bubonic Plague (Black Death) and what was its impact between 1346–50?

It was caused by the bacteria Yersenia pestis. It caused 50 million deaths, resulting in nearly 1/2 of Europe perishing.

What virus variants cause Smallpox, and what are the effects of the disease?

Caused by two airborne virus variants, Variola major and Variola minor; it is a deadly disease that, in survivors, can cause disfigurement and blindness.

Why is the Hepatitis B virus (HBV) a high risk for health care workers?

HBV causes an infectious inflammatory illness of the liver (Hepatitis B), and the virus is 50 to 100 times more infectious than HIV.

What are the three tenets of the Cell theory?

1. All living things are made of cells. 2. Cell can only come from other cells. 3. All functions of a living thing are carried out in cells.

Define Prokaryotic cells and state where they are found.

Prokaryotic cells are lacking a membrane-enclosed nucleus and membrane-enclosed organelles; they are found in bacteria and archaea.

What does the Greek meaning of Prokaryotics and Eukaryotes signify?

Prokaryotics means “before nuclei,” and Eukaryotes means “true nucleus”.

How do bacteria replicate quickly?

By dividing in two through a process called binary fission.

What is the composition and function of bacterial Flagella?

They are composed of a protein called flagellin and allow bacteria to move toward a more favourable environment.

What is the primary function of Pili (fimbriae)?

They are hair-like structures that enable bacteria to stick to surfaces.

Distinguish between the bacterial Slime layer and Capsule regarding attachment.

The Slime layer easily detaches from the cell wall and enables gliding/sliding; the Capsule is firmly attached to the cell wall and has an antiphagocytic function to protect the bacteria from being ingested by phagocytic white blood cells.

What is the purpose of bacterial endospores?

They are a means of survival when the bacteria's moisture or nutrient supply is low.

Why are endospores characterized as "VERY difficult to kill"?

They are resistant to heat, cold, drying, most chemicals, disinfectants, and boiling, and can survive for many years.

What are three functions of the eukaryotic Cell membrane?

It transports substances in and out of cells, performs phagocytosis (engulfment of foreign material), and performs pinosytosis (engulfs liquids rather than solids).

What is the function of the Cell wall, and in which eukaryotes is it found?

It gives shape and strength to the cell and protects against osmotic imbalances; it is found only in plants.

Which eukaryotic organelles are responsible for protein synthesis?

Endoplasmic reticulum and Ribosome.

What are the characteristics of Protozoa?

They are unicellular, non-photosynthetic, motile, require organic food, and many can form cysts and serve as a site for spreading pathogens.

What are the characteristics of Fungi?

They are non-photosynthetic and grow well in dark, moist environments; few species are pathogenic to humans.

What is Aerobic Respiration?

It is breathing using oxygen; a chemical reaction whereby organic compounds like glucose are converted into energy for the cell, using oxygen from the environment.

What is Anaerobic Respiration?

A process whereby respiration takes place without oxygen, occurring only in some groups of bacteria living in anaerobic environments like soil and stagnant water.

What is Fermentation?

A metabolic process converting sugar to acids, gases and/or alcohol using yeast or bacteria.

What distinguishes Obligate Anaerobes?

They will die when exposed to atmospheric levels of oxygen and acquire energy ONLY by fermentation.

What distinguishes Facultative Anaerobes?

They may or may not use oxygen when it is present and can switch between aerobic respiration and anaerobic respiration depending on the environment.

What are Microaerophiles?

Organisms that may use oxygen, but only at low concentrations