Microbiology Exam 1

microorganism (microbe)

an organism that requires a microscope to be seen

cell

the smallest unit that possesses all the characteristics of life

Microbiology

The study of microbes and their interactions with each other and the
environment

Species

Microbes that share a set of genes and traits

scientific name

binomial name where the genus comes first and the species comes second. The genus is capitalized and the entire name is italicized

Genome

The total complement of DNA in an organism.

relatedness of microbes

investigate the genomes

Robert Hooke

First to study living materials under a microscope. Coined the term cell

Antoni van Leeuwenhoek

First to study and document microbes using a microscope

Spontaneous Generation

Theory that microbes arise spontaneously from non-living matter

Lazzaro Spallanzani

Observed dividing microbes using a microscope

Louis Pasteur

French foundational microbiologist. Noted for his refutation of spontaneous
generation, discovery that microbes are responsible for wine production and spoilage, and development of the first vaccines based on weakened pathogens. He set up an experiment which proved microbes arise from pre-existing microbes that contaminate a sample

Florence Nightingale

Nurse who developed modern nursing practices. She also applied statistics to medical science, which become the foundation of epidemiology

Epidemiology

The study of how diseases spread through and affect populations

Robert Koch

German microbiologist. Developed many important microbiology techniques that are still used today including the use of agar plates to generate colonies, picking colonies into liquid culture to generate a pure culture, and the germ theory of disease

colonies

distinct populations of bacteria

Germ Theory of Disease

Specific diseases are caused by the presence of specific microorganisms

Koch’s postulates

Criteria to determine if a pathogen is responsible for a specific disease

1. Suspected microbe is always present in diseased host (absent in healthy host)

2. Isolate pure culture of suspect microbe from diseased host

3. Introduce suspect microbe into healthy host

4. If host becomes sick with original disease, isolate the same pathogen from new host

Koch’s 4 Postulates

Ignaz Semmelweis

Pioneered the use of antiseptics in operating rooms. Antiseptics are chemical agents that kill microbes

Joseph Lister

First used carbolic acid (phenol) on surgical instruments

Antibiotics

Organic compounds produced by microbes to kill other microbes

Sergei Winogradsky

Foundational microbiologist who studied microbes in natural environments, specifically soils and wetlands

lithotrophs

Organisms that gain energy from inorganic molecules

enrichment media

Favors the growth of certain species over others

Nitrogen fixation

Converting atmospheric nitrogen into biologically useful molecules (Only certain prokaryotes can do this)

Symbiosis

Growth of two species in intimate association

Mutualism

Both species benefit

Endosymbiosis

One organism grows inside of another

Lyn Margulis

hypothesized mitochondria and chloroplasts of eukaryotic cells evolved from endosymbiotic bacterial ancestors, developed theory of endosymbiosis

Carl Woese

pioneered the use of rRNA to study evolutionary relationships and proposed
the modern three domains of life

Rosalind Franklin, James Watson, and Francis Crick

propose four bases make up the DNA double helix in 1953

Fred Sanger

develops DNA sequencing technology in 1977

Haemophilus influenza

The first organism sequenced using DNA sequencing

Microbiome

The collection of all microbes on and in the human body

Colonization

The ability of a microbe to stay attached to a body surface replicate

Adhesins

Proteins that enable microbes to attach to host cells

Pathogen

Any bacterium, virus, fungus, protozoan, or helminth that causes disease

Pathogenicity

Ability of an organism to cause disease

Infection

When a pathogen enters and begins to grow in the host. Most infections do not result in disease

Disease

Disruption of the normal structure or function of a body part, organ, or symptom that can be recognized by a characteristic set of symptoms and signs

Signs

Observed by examination (objective marker of disease)

Symptoms

Experienced by the patient (subjective marker of disease)

Syndrome

Collection of signs and symptoms that collectively characterize a
disease

Acute

Symptoms develop and resolve rapidly

Chronic

Symptoms develop gradually and resolve slowly

Latent

Pathogen cannot be cultured but is still present. May persist for years

Primary Pathogen

A pathogen that can breach host defenses and cause disease in
healthy individuals

Opportunistic pathogen

A pathogen that causes disease in immunocompromised
individuals

Virulence

Severity of a disease caused by a pathogen

Lethal Dose 50%

Number of pathogens that kill 50% of an infected
population

Infectious Dose 50%:

Number of pathogens that induce disease symptoms
in 50% of an infected population

Invasion

Entry of a pathogen into a host cell

Invasiveness

Ability of a pathogen to spread through tissue

Host Range

The organisms a pathogen can infect and produce disease in. Can be narrow (one species) or broad (many different species)

Attachment

Proteins are used to adhere to host cells and tissue. Typically bind host surface molecules

Immune avoidance

Pathogens must circumvent the immune system. Many
different ways to accomplish this

Steal nutrients

Acquire nutrients the host would normally use.

Infectious disease

A disease caused by a pathogen that can be transferred from
one host to another

Immunopathology

Signs and symptoms that are caused by the immune systems
response to the pathogen

Morbidity

Rate of illness in population due to a disease

Mortality

Rate of death in population due to a disease

Sequelae

Pathological consequences that develop after a disease resolve

Incubation phase

From infection to appearance of first signs

Prodromal phase

Non-specific symptoms

Illness phase

Characteristic signs and symptoms of disease

Decline phase

Symptoms subside

Convalescence phase

Patient recovers original health state

Infection cycle

Route of transmission from one host to another

Horizontal transmission

The pathogen is transferred from one host to another

Vertical transmission

The pathogen is transferred from parent to offspring

Direct contact transmission

Pathogen spread due to physical contact from host to host

Indirect transmission

Pathogen spread through an intermediary airborne, fomites, vehicles, or vectors

fomites

inanimate objects that spread a pathogen

vehicles

food, water, or air that spread a pathogen

vectors

animals that spread a pathogen

Reservoir

An animal or environmental source that normally harbors a pathogen

Asymptomatic carrier

Host that harbors the pathogen but does not present disease condition

Endemic

Disease always present in a population at a low rate

Epidemic

Increase in number of disease cases in a population in a short time

Pandemic

Worldwide epidemic

Zoonotic Disease

Pathogens in animals that can be transmitted to humans

Portals of entry/exit

location by which the pathogen enters or exists the host. A pathogen may utilize different ports for entry and for exit, including fecal-oral, skin, respiratory, urogenital, parenteral, and ocular ports

Biosafety Levels

Regulations for labs handling various pathogens

BSL 1

Non-pathogens

BSL 2

Moderate pathogens

BSL 3

Pathogens that cause infection via inhalation

BSL 4

Dangerous/exotic pathogens that cause infection via inhalation

Host Disease Factors

Many different factors influence an individual’s susceptibility to a disease, including age, genetics, hygiene and behavior, nutrition and exercise, pre-existing conditions, occupation, and immune status

Emerging disease

New disease recently appeared in a population

Reemerging disease

Known disease whose rate is increasing in a population

Magnification

Increase in the apparent size of an image, occurs because as light passes the focal point, the rays spread out the image over a larger area

Resolution

The small distance two objects can be distinguished

Properties of Light

Light propagates as waves

Wavelength

Distance between one peak to the next

Wavelength of visible light

400 – 750 nm

Contrast

Difference in light intensity between background and object

Wavelength Conditions to Visualize Object

Light wavelength must be smaller than object

Detection

Small wavelengths must be spread out (magnified) so that our eyes can perceive them

Absorption

Light absorbed by object (generates heat)