Introduction, Classification, and History of Microbiology

Question 1

Why are microorganisms important? (6 parts)

Answer 1

Most populous and diverse group of organisms
Found everywhere on the planet
Recycle essential elements
Source of nutrients and photosynthesis (some)
Benefit to society due to food, antibiotic, etc., production
Disease

Question 2

What are microorganisms?

Answer 2

Organisms and acellular entities too small to be clearly seen by the unaided eye
Lack highly differentiated cells and distinct tissues

Question 3

Prokaryotic cells

Answer 3

Lack a true membrane-delimited nucleus

Question 4

Eukaryotic cells

Answer 4

Have a membrane enclosed nucleus, are morphologically complex, and are larger than prokaryotic cells

Question 5

What are the three domains of microorganisms?

Answer 5

Bacteria, Archaea, and Eukarya

Question 6

Domain Bacteria

Answer 6

Usually single celled
Majority have cell wall with peptidoglycan
Most lack a membrane-bound nucleus
Ubiquitous and some live in extreme environments

Question 7

Domain Archaea

Answer 7

Distinguished from bacteria by unique rRNA gene sequences
Lack peptidoglycan in cell walls
Have unique membrane lipids
Some have unusual metabolic characteristics
Many live in extreme environments

Question 8

What are the two types of organisms in Domain Eukarya?

Answer 8

Protists and fungi

Question 9

Protist examples

Answer 9

algae-photosynthetic
protozoa- can be motile
slime molds
water molds

Question 10

Fungi characteristics

Answer 10

unicellular- yeast
multicellular- mold

Question 11

What are the four kinds of acellular agents?

Answer 11

Viruses, viroids, virusoids, and prions

Question 12

Virus characteristics

Answer 12

smallest of all microbes
requires host cell to replicate
causes range of diseases, some cancers

Question 13

What are viroids and virusoids?

Answer 13

infectious agents composed of RNA

Question 14

what are prions?

Answer 14

infectious proteins

Question 15

Antony van Leeuwenhoek

Answer 15

first person to observe and describe microorganisms accurately

Question 16

what is spontaneous generation?

Answer 16

idea that living organisms can develop from nonliving or decomposing matter

Question 17

who discredited spontaneous generation and how?

Answer 17

Francesco Redi
showed that maggots on decaying meat came from fly eggs

Question 18

what is the order of flask boiling that showed no growth of microorganisms?

Answer 18

sealed and then boiled

Question 19

Louis Pasteur

Answer 19

used flasks with long, curved necks and left exposed to air. there was no growth of microorganisms

Question 20

was the role of microorganisms in disease immediately obvious?

Answer 20

no. it was believed to be caused by an imbalance in the body humors

Question 21

what did Joseph Lister do?

Answer 21

provided indirect evidence that microorganisms were the casual agents of disease
developed surgical procedure to prevent microorganisms from entering wounds and through treating of instruments and wound dressings

Question 22

Robert Koch

Answer 22

established the relationship between Bacillus anthracis and anthrax
used criteria created by Jacob Henle, named them Koch’s postulates

Question 23

What are the four Koch’s Postulates?

Answer 23

1. The microorganism must be present in every case of the disease but absent from healthy organisms
2. The suspected microorganism must be isolated and grown in pure culture
3. The same disease must result when the isolated microorganism is inoculated in a healthy host
4. The same microorganism must be isolated again from the diseased host

Question 24

What did Koch’s work lead to?

Answer 24

agar
petri dishes
nutrient broth and agar
methods for isolating microorganisms