Mircobiology Lecture 1

What is the etymological breakdown of the word Microbiology from its Greek roots?

Mikros (small), Bios (life), and Logos (discourse, study)

Microbiology

the study of living things that are too small to be seen with the naked eye

Name the six main types of organisms referred to as microorganisms or microbes.

Bacteria, Virus (acellular), Protozoa, Fungi, Algae, Helminths

Who created the original classification system in 1758 that categorized all macroscopic organisms as either animal or plant?

Carl Linnaeus

What is the defining characteristic that distinguishes prokaryotes from eukaryotes?

Prokaryotes lack a true membrane-delimited nucleus, while eukaryotes have one.

An exception to the rule is that prokaryotes lack a membrane-delimited nucleus.

Phylum Planctomycetes

List four features typically found in eukaryotic cells but absent in prokaryotic cells.

1. Nuclear Membrane

2. Mitochondria

3. Golgi

4. ER

What five-kingdom classification scheme was developed around 1969 after the discovery of the prokaryote-eukaryote difference?

Monera, Protista, Fungi, Animalia, and Plantae

In the five-kingdom scheme, which kingdom contained all prokaryotes?

Monera

What modern classification scheme, developed around 1990, is now used instead of the five-kingdom?

The three-domain system

The three-domain system is based on a comparison of what specific type of genes?

Ribosomal RNA (rRNA) genes

What are the three domains in the modern biological classification system?

Archaea, Bacteria, Eukarya

Which domain consists of unicellular prokaryotes with distinct metabolism, often found in extreme environments?

Archaea

Which domain consists of true bacteria that are unicellular, prokaryotic, and found almost everywhere?

Bacteria

The domain Eukarya includes organisms whose cells have a ______ and other mmebrane-bound organelles.

nucleus

What is considered the best direct evidence for the nature of primitive life?

The fossil record

Why is the fossil record for microbes considered sparse?

Because geological forces can create objects that resemble cells, leading to skepticism about fossil authenticity

In modern cells, what molecule stores hereditary information?

DNA

In modern cells, what molecule converts the information stored in DNA into protein?

RNA

According to the RNA World Hypothesis, what type of molecule could perform both cellular work and replication in early life?

RNA

What is a ribozyme?

An RNA molecule that functions as a catalyst, performing cellular work and replication

What hypothesis explains the origin of mitochondria and chloroplasts in eukaryotic cells?

The Endosymbiotic Hypothesis

Endosymbiosis

an interaction between two organisms where one organism lives inside the other

According to the Endosymbiotic Hypothesis, the genome sequences of mitochondria are closely related to which bacteria?

Rickettasia

According to the Endosymbiotic Hypothesis, the genome sequences of genome are closely related to which bacteria?

Prochloron

What are the two primary mechanisms bacteria use to increase genetic diversity?

Mutation and Horizontal gene transfer (HGT)

What is horizontal gene transfer (HGT)?

The transfer of genetic information from a donor organism to a recipient, creating a new genotype

In microbiology, what is the definition of a species?

a group of interbreeding natural populations that is reproductively isolated from other groups.

In microbiology, ______ is define as the descendants of a single, pure microbial culture.

strain

The scientific naming system that uses a genus and species epithet, such as Yersinia pestis, is called ______ _______.

binomial nomenclature

Who developed a crude microscope in 1665 and was the first to determine that life’s smallest structural units were cells?

Robert Hooke

Robert Hooke coined the term cells after observing tiny, hollow compartments in what material

thin slices of cork

Who is known as the Father of Microbiology for being the first person to observe and describe microbes accurately?

Antonie van Leeuwenhoek

What did Antonie van Leeuwenhoek call the single-celled organisms he observed in pond water?

Animalcules

What is the theory of spontaneous generation?

The idea that living organisms can develop from nonliving or decomposing matter.

Who disproved the idea of spontaneous generation of microorganisms using Swan-neck flask experiments?

Louis Pasteur

The process of heating wine or other substances to kill contaminating microbes, developed by Pasteur is known as _______.

Pasteurization

What is the Germ Theory of Disease?

The theory that diseases are caused by the growth of microbes in the body.

Who advocated hand washing in 1840s after correlating infections in maternity wards with physicians coming from autopsies?

Ignaz Semmelweis

Who is credited with developing aseptic techniques for surgery, using heating and phenol to prevent microbial entry into wounds?

Jospeh Lister

Who established the relationship between Bacillus anthracis and anthrax, providing final proof for the Germ Theory of Disease?

Robert Koch

The criteria used to establish the l ink between a particular microorganism and a particular disease are known as _____ _______

Koch’s postulates that

Who suggested the use of agar instead of gelatin for creating solid culture media in Koch’s lab?

Fanny Hesse

The Petri dish was invented by Julius Petri, who was trained in the lab of which prominent microbiologist?

Robert Koch

Who first detected viruses in 1898 by showing that filtered tobacco plant extracts were still infectious?

Martinus Beijerinck

What did Pasteur call the weakened microbial strains that lost their ability to cause disease but could confer immunity?

Attenuated strains

Pasteur developed vaccines for which two diseases?

Anthrax (for sheep) and rabies (for humans)

Who were the first to describe the actions of a soluble substance in the blood (antibodies) that protected against toxins?

Emil von Behring and Shibasaburo Kitasato

Immunology

The study of how the immune system protects a host from pathogens

What is the term for the measure of how greatly a substance slows the velocity of light?

Refractive index

For a lens, the distance between its center and the point where light rays converge is called the __ ___.

focal length

A lens with a short focal length will have ___ magnification than a lens with a long focal length

more

What is the definition of microscope resolution?

the ability of a lens to separate or distinguish small objects that are close together.

What is the purpose of using immersion oil with a microscope objective?

It increases the numerical aperture and resolution by preventing light rays from reflecting or refracting away from the objective lens.

In a ______ microscope the image is formed by light reflected or refracted by the specimen, producing a bright image against a dark background.

dark-field

Which type of microscope is used to identify bacteria alike Treponema pallidum, the agent of syphilis?

The dark-field microscope

Which microscope converts differences in refractive index and cell density into variations in light intensity, making it excellent for observing living cells?

The phase-contrast microscope

The _______ microscope exposes a specimen to ultraviolet, violet, or blue light and shows a bright image from light emitted by the specimen itself.

fluorescence

What is the function of a fluorochrome in florescence microscopy?

It is a fluorescent dye used to stain specimens so they emit light when illuminated,

Which type of microscopy uses a laser beam and an aperture to create a sharp, composite 3D image, and is useful for studying biofilms?

Confocal scanning laser microscopy (CLSM)

What are the three main purposes of preparing and staining specimens for microscopy?

To increase visibility, accentuate specific morphological denatures, and preserve specimens

What is fixation in the context of specimen preparation?

the process that preserves internal and external structures and fixes them in position on a microscope slide

Which fixation method preserves overall morphology but not internal structures and is routinely used for bacteria?

heat fixation

Which fixation method protects fine cellular substructure and is used for larger, more delicate organisms?

chemical fixation

In staining, basic dyes have _______ charges, while acid dyes have _______ charges.

positive; negative

What is a simple stain?

A staining procedure where a single stain is used to determine size, shape, and arrangement of bacteria

In a _______ stain, such as the India Ink Stain, the background is colored but the remains unstained.

negative

What is the purpose of a differential stain?

To divide microorganisms into groups based on their staining properties (ex. gram stain) or to detect specific structures

What is the most widely used differential staining procedure in bacteriology?

Gram staining

The Gram stain divides bacteria into two groups, Gram-positive and Gram-negative, based on differences in their _______ ______ structure.

cell wall

The acid-fast stain is particularly useful for staining members of which bacterial genus?

Mycobacterium

What substance in the cell walls of Mycobacterium is responsible for their acid-fast staining characteristics?

Mycolic acid (a high lipid content)

Which staining technique is a heated, double staining method used to visualize a dormant structure within a bacterium?

Endospore staining

A _________ stain is used to visualize polysaccharide layers surrounding some bacteria, often appearing as a colorless area against a stained background

capsule

In flagella staining, what is the purpose of applying a mordant

To increase the thickness of the flagella so they can be seen with a light microscope

Electron microscopy achieves much higher resolution than light microscopy because the wavelength of the _____ _____ is much shorter than that of light

electron beam

In a Transmission Electron Microscope (TEM), denser regions of the specimen scatter more electrons and therefore appear _______ in the final image.

darker