Microbiology Quiz #1

Robert Hooke

* Wrote Micrographia
* Coined “cell” term

Antonie van Leeuwenhoek 

* Father of Microbiology
* discoverer of microbial world
* described moving stuff as “animalcules”

Aristotle

Spontaneous generation

What is spontaneous generation?

Spontaneous generation is the outdated belief that living organisms can arise spontaneously from non-living matter.

In the 17th century, people believed in spontaneous generation, the idea that living organisms could arise from non-living matter. This theory was disproven by Louis Pasteur, who showed that maggots only appeared when flies laid their eggs on decaying meat.

How did Leeuwenhoek disprove SG?

suggested maggots arose from eggs in the decaying material, not the material itself.

How did Francesco Redi disprove SG?

found that if flies were prevented from landing on meat, it did not produce maggots.

Louis Pasteur

* disproved SG with Swan neck flask experiment
* Germ Theory: microorganisms cause disease

Joseph Lister

started sterile surgeries

Robert Koch

Koch’s Postulates

Koch's Postulates: criteria to link microorganism and disease.


1. Microorganism in disease cases, not in healthy individuals.
2. Isolate and grow microorganism in pure culture.
3. Inoculate microorganism into healthy host to cause disease.
4. Re-isolate microorganism from infected host.

Importance: Revolutionized microbiology, identifies disease-causing agents.

Limitations: Some diseases can't be studied using Koch's Postulates due to ethical or practical reasons.

Modern Modifications: Adjusted for new knowledge and techniques in microbiology.

Edward Jenner

Father of vaccination

Prokaryotes

no nucleus or organelles

Eukaryotes

has nucleus and membrane-bound organelles

Fungi

multicellular organisms

viruses

obligate intracellular parasites that req living cells to grow

Alexander Fleming

penicilin

Archaea

type of prokaryote that is an extremophile (needs extreme environment to grow)

Shapes of Bacteria

* Cocci (spheres)
* Rods/Bacilli
* SpiralsW

What is a nucleoid?

bacterial chromosome

What are Pili

thin protein fibers extending from surface

2 types of Pilli

1. Fimbrae
2. Conjugation (sex) Pili

What is the function of Fimbrae?

allows for attachment to tissue

What is the function of conjugation (sex) pili?

* allows for exchange of DNA
* allows for exchange antibiotic resistance genes

Function of flagella

1. motility (sperm propel movement)
2. chemotaxis (move bacteria towards nutrients/chemicals)
3. allows for attachment to tissues

glycocalyx

adhering (sticky) layer of polysaccharides

functions of glycocalyx

* protect
* attachment
* prevent dehydration

Do all bacteria have cell walls?

No

What do cell walls contain?

peptidoglycan (NAG/NAM/Amino acid)

Gram positive bacterial cell walls have?

peptidoglycan and techoic acid

Gram negative bacterial cell walls have?

peptidoglycan and LPS (lipid A or endotoxin)

Plasmids

small circular pieces of DNA that allow for resistance exchange between two bacterium

Domains of life (3)

Arcahea, Bacteria, Eukarya

Arcahea and Bacteria are?

Prokaryotes

Eukarya are?

Eukaryotes

Eukarya include?

• multicellular kingdoms of plants

• fungi animals

• single-celled protists

ER

• Transport proteins (rough ER).

• Synthesize and transport lipids (smooth ER)

Golgi Apparatus

Modify, sort, package proteins

Lysosomes

• Digest proteins.

• Control cell metabolism and growth.

cilia

cell motility

resolution

most important feature on microscope ; ability to distinguish between two very small objects

light microscopy

Visible light passes through multiple lenses and through the specimen

darkfield microscopy

shows the specimen against a dark background and provides good resolution.

Fluorescence microscopy

specimens are coated with fluorescent dye and illuminated with ultraviolet light. 

simple stain

Bacterial cell walls have neg. charge; use basic dye which have pos. charge; they attract so color appears

negative stain

A technique in microbiology where the background is stained, leaving the bacteria unstained. This creates a contrasting image of the bacteria against a dark background. It is useful for visualizing the shape, size, and arrangement of bacteria.

gram stain technique

• 4 diff steps and must be done in specific order

• separates into gram positive(blue/purple) or gram negative (orange)

gram positive shows up as?

blue/purple

gram negative shows up as?

red/orange

a thick glycocalyx is called?

capsule

binary fission

• how bacteria reproduce

• The cell doubles in mass

• DNA replicates and the two strands separate

• Synthesis of a partition or septum separates the cell into two genetically identical cells.

final no. of cells equation

2^n

bacterial growth curve

illustrates the dynamics of growth in 4 phases

• lag phase

• log phase

• stationary phase

• decline phase

Lag phase

• no cell division occurs as bacteria adapts to environment

• producing enzymes to breakdown nutrients

log phase

• very rapid phase

• reproduces rapidly

• phase where antibiotics work best as symptoms roll out

Stationary phase

• fighting for survival

• reproductive and death rates equalize due to running out of nutrients

Decline (exponential death) phase

nutrients/resources run out so it dies

Endospores

highly resistant structure formed when nutrients are low

• Bacillus

• Clostridium

Bacillus are

aerobic

Clostridium are

anaerobic

Dipicholinic acid

• present in spores to stabilize them

• makes up most of its weight

Germination

the process of a spore turning into a vegetative cell

vegetative cell

once turned into this, it can secrete things and create an imapct

what are endospores resistant to?

1. desiccation

2. heat

Formation of a Spore (4)

1. stressed cell divides and creates spore and mother cell

2. prespore contains: dipoclinic acid which stabilizes

3. mother cell matures prespore into endospore

4. mother cell disintegrates, frees spores

Psychrophiles

• grow in cold weather

• most abundant prokaryotes

mesophiles

• thrive in intermediate weather (human body temp)

• most bacterial pathogens

thermophiles

• grow in hot temps

• do not cause disease in humans

hyperthemrophiles

• grow in extremely hot temps

• type of archaea

Obligate aerobes

req. oxygen to grow

anaerobes

no oxygen req./possible to grow

facultative prokaryotes

can grow with or without oxygen

capnophilic

req low oxygen and much carbon dioxide

barophiles

can withstand much pressure

halophiles

salt-loving pathogens

Mutualism

relationship between two organisms where both parties benefit

symbiosis

living together

• positive

• negative

• neutral

parasitism

• neg. relationship b/tween organism and urself

• form of symbiosis in which pathogen benefits and causes damage to host; might result in disease

Pathogenicity

likelihood an infection will result in disease

Virulence

ability/ potency to do harm to a host after infection; degree of pathogenicity

• ex: staph infection and ebola are both contracted, which one is worse? ebola has higher level of virulence factors (potency)

Virulence factors

Things the organism produces or secretes that makes them more dangerous or easier for them to cause disease

diagnosis

• evaluation of patient signs and symptoms based on physical exam and medical history

signs

type of body abnormality that can be detected by observers

• objective/can be measured

  • E.g., blood pressure, fever on therm., lab results

Symptoms

changes in body function sensed by patient 

• subjective

• aches, pains, tiredness

Clinical infection/symptomatic

infected patient experiences symptoms an visits doctor

subclinical infection/asymptomatic/presymptomatic

no symptoms in patient or patient has not yet shown symptoms

• infected but they don’t know/feel it

Syndrome

signs and symptoms are very specific to only certain diseases

• patient shows certain symptoms that point to it being AIDS (meets AIDS criteria)

Reservoir

where a high concentration of something is found

3 types of reservoirs

1. Animal reservoirs

2. Human reservoirs

3. Environmental reservoirs

Animal reservoirs (2)

• Reservoir host: animals in which pathogen survives and multiplies

• Intermediary host: amplifies the infectious agent but may not experience symptoms; transmits it to humans

  • ex: bat has ebola, bites gorilla, gorilla is intermediary host, transmits it to humans

Human reservoirs

Humans are primary source of disease

Carriers (human reservoir)

individual capable of spreading infectious agents

• Ex: typhoid fever is contracted thru contaminated food/water. The person has signs/symptoms, they recover, and the bacteria resides in them. They become source of infection even if they don’t show signs/symptoms when they eliminate waste since it resides in their body.

Superspreaders (human reservoir)

often asymptomatic reservoirs that spread diseases on a larger scale than the average person does

• ex: someone has covid and is asymptomatic; they go out in public and spread it without knowing

types of indirect contact (3)

1. fomites

2. vehicle transmission (food/water)

3. vector transmission (zoo)

fomites (indirect contact)

inanimate objects/surfaces on which pathogens linger 

• ex: germs on table

Vector transmission (indirect contact)

zoonotic (animal) method of disease transmission

• Mechanical vectors

• Biological vectors

Vector transmission: Mechanical Vectors

passive transport of microbes on body parts

• ex: somebody has salmonella and deficates; fly sits on waste and bacteria gets on it; fly lands on something you touch (transporting the pathogen to one site to another thru animal)

Vector transmission: Biological vectors

must multiply inside that animal before transmission

• Ex: malaria is transmitted thru mosquitoes; bites person w/ malaria; pathogen replicates inside it; flies around and bites someone else transmitting to other person

Direct Contact Types

1. Close Contact

2. Horizontal transmission

3. Vertical Transmission

Direct Contact: Horizontal Transmission

transferring by touch/bite

• ex: handshaking, kissing

Direct Contact: Vertical Transmission

mother spreads to baby

• ex: mother has herpes; baby goes thru vaginal canal during birth and contracts it

Airborne Transmission Types (2)

1. Respiratory droplets

2. Aerosols