Chp. 1 Introduction to Microbiology, scientists

Question 1

What are Koch’s postulates?

Answer 1

25

Question 2

What was the significance of the swan neck flask in Pasteur’s experimets?

Answer 2

a

Question 3

What is a prion? What diseases are caused by prions?

Answer 3

a

Question 4

Prokaryote

Answer 4

1 Cell
Bacteria
Archae

Question 5

Eukaryote

Answer 5

1 cell or muticellular, “animal like”
Protozoa-
Algae
Helminths

Question 6

Bacillus

Answer 6

rodlike

Question 7

Coccus

Answer 7

spherical or ovoid

Question 8

Spiral

Answer 8

corkscrew or curved

Question 9

Peptidoglycan

Answer 9

Bacteria are enclosed in cell walls that are largely composed of a carbohydrate and protein complex

Question 10

Binary Fission

Answer 10

Bacteria generally reproduce by dividing into two equal cells

Question 11

Robert Hooke - 1665

Answer 11

After observing a thin slice of cork through a relatively crude microscope, Englishman Hooke, reported to the world that life’s smallest structural units were “little boxes,” or “cells,” as he called them. Using his improved version of a compound microscope (one that uses two sets of lenses), Hooke was able to see individual cells. Hooke’s discovery marked the beginning of CELL THEORY–the theory that all living things are composed of cells. Subsequent investigations into the structure and function of cells were based on this theory.

Question 12

Anton van Leeuwenhoek - 1673-1723

Answer 12

Though Hooke’s microscope was capable of showing large cells, it lacked the resolution that would have allowed him to see microbes clearly. The Dutch merchant and amateur scientist, was probably the first actually to observe live microorganisms through the magnifying lenses of more than 400 microscopes he constructed. Between 1673-1723, he wrote a eries of letters to the Royal Society of London describing the “animalcules” he saw through his simple, single lens microscope. Van Leeuwenhoek made detailed drawings of “animalcules” he found in rainwater, in his own feces, and in material scraped from his teeth. These drawings have been identified as representations of bacteria and protozoa.

Question 13

Spontaneous Generation

Answer 13

After van Leeuwenhoek discovered the previously “invisible” world of microorganisms, the scientific community of the time became interested in the origins of these tiny living things. Until the second half of the nineteenth century, many scientists and philosophers believed that some forms of life could arise spontaneously from nonliving matter; Not much more than 100 years ago, people commonly believed that toads, snakes, and mice could be born of moist soil; that flies could emerge from manure; and that maggots (which we now know are the larvae of flies) could arise from decaying corpses.

Question 14

Francesco Redi - 1668

Answer 14

A strong opponent of spontaneous generation, Redi set out in 1668 to demonstrate that maggots did not arise from decaying meat. Redi filled two jars with decaying meat. The first was left unsealed; the flies laid their eggs on the meat, and the eggs developed into larvae. The second jar was sealed, and because the flies could not lay their eggs on the meat, no maggots appeared. Still, Redi’s antagonists were not convinced; they claimed that fresh air was needed for spontaneous generation. So Redi set up a second experiment, in which he covered a jar with a fine net instead of sealing it. No larvae appeared in the gauze-covered jar, even though air was present. Maggots appeared only when flies were allowed to leave their eggs on the meat. Redi’s results were a serious blow to the long-held belief that large forms of life could arise from nonlife. However, many scientists still believed that small organisms, such as van Leeuwenhoek’s “animalcules” were simple enough to be generated from nonliving materials.

Question 15

John Needham - 1745

Answer 15

The case for spontaneous generation of microorganisms seemed to be strengthened in 1745, when Needham, an Englishman, found that even after he heated nutrient fluids (chicken broth and corn broth) before pouring them into covered flasks, the cooled solutions were soon teeming with microorganisms. Needham claimed that microbes developed spontaneously from the fluids.

Question 16

Lazzaro Spallanzani - 1765

Answer 16

Twenty years after Needham, Italian scientist, Spallanzani, suggested that microorganisms from the air probably entered Needham’s solutions after they were boiled. Spallanzani showed that nutrient fluids heated AFTER being sealed in a flask did not develop microbial growth. Needham responded by claiming the “vital force” necessary for spontaneous generation had been destroyed by the heat and was kept out of the flasks by the seals. The intangible “vital force” was given al the more credence shortly after Spallanzani’s experiment, when Anton Laurent Lavoisier showed the importance of oxygen to life. Spallanzani’s observations were criticized on the grounds that there was not enough oxygen in the sealed flasks to support microbial life.

Question 17

Rudolf Virchow - 1858

Answer 17

The issue was still unresolved in 1858, when German scientist Virchow challenged the case for spontaneous generation with the concept of BIOGENESIS, the claim that living cells can arise only form preexisting living cells. Because he could offer no scientific proof, arguments about spontaneous generation continued until 1861

Question 18

Louis Pasteur - 1861

Answer 18

The issue was finally resolved with a series of ingenious and persuasive experiments, Pasteur demonstrated that microorganisms are present in the air and can contaminate sterile solutions, but that air itself does not create microbes. He filled several short-necked flasks with beef broth and then boiled their contents. Some were then left open and allowed to cool. In a few days, these flasks were found to be contaminated with microbes. The other flasks, sealed after boiling, were free of microorganisms. From these results, Pasteur reasoned that microbes in the air were the agents responsible for contaminating nonliving matter. Pasteur next placed broth in open-ended, long-necked flasks and bent the necks into S-shaped curves. The contents of these flasks were then boiled and cooled. The broth in the flasks did not decay and showed no signs of life, even after months. Pasteur’s unique design allowed air to pass into the flask, but the curved neck trapped any airborne microorganisms that might contaminate the broth. Pasteur showed that microorganisms can be present in nonliving matter–on solids, in liquids, and in the air. Furthermore, he demonstrated conclusively that microbial life can be destroyed by heat and that methods can be devised to block the access of airborne microorganisms to nutrient environments.

Question 19

Aseptic techniques

Answer 19

Techniques that prevent contamination by unwanted microorganisms, which are now the standard practice in laboratory and many medical procedures. Modern aseptic techniques are among the first and most important concepts that a beginning microbiologist learns.

Question 20

The Golden Age of Microbiology - 1857-1914

Answer 20

During this period, rapid advances, spearheaded mainly by Pasteur and Robert Koch, led to the establishment of microbiology as a science. Discoveries during these years included both the agents of many diseases and the role of immunity in preventing and curing disease. During this productive period, microbiologists studied the chemical activities of microorganisms, improved the techniques for performing microscopy and culturing microorganisms, and developed vaccines and surgical techniques.

Question 21

Fermentation and Pasteurization

Answer 21

One of the key steps that established the relationship between
microorganisms and disease occurred when a group of
French merchants asked Pasteur to find out why wine and beer
soured. They hoped to develop a method that would prevent
spoilage when those beverages were shipped long distances. At
the time, many scientists believed that air converted the sugars
in these fluids into alcohol. Pasteur found instead that microorganisms
called yeasts convert the sugars to alcohol in the
absence of air. This process, called fermentation (see Chapter
5, page 130), is used to make wine and beer. Souring and spoilage
are caused by different microorganisms called bacteria. In
the presence of air, bacteria change the alcohol into vinegar
(acetic acid).
Pasteur’s solution to the spoilage problem was to heat the
beer and wine just enough to kill most of the bacteria that
caused the spoilage. The process, called pasteurization, is now
commonly used to reduce spoilage and kill potentially harmful
bacteria in milk as well as in some alcoholic drinks. Showing
the connection between food spoilage and microorganisms was
a major step toward establishing the relationship between disease
and microbes.

Question 22

The Germ Theory of Disease

Answer 22

The realization that yeasts play a crucial role in fermentation
was the first link between the activity of a microorganism and
physical and chemical changes in organic materials. This discovery
alerted scientists to the possibility that microorganisms
might have similar relationships with plants and animals—
specifically, that microorganisms might cause disease. This idea
was known as the germ theory of disease.

The germ theory was a difficult concept for many people to
accept at that time because for centuries disease was believed
to be punishment for an individual’s crimes or misdeeds.
When the inhabitants of an entire village became ill, people
often blamed the disease on demons appearing as foul odors
from sewage or on poisonous vapors from swamps. Most people
born in Pasteur’s time found it inconceivable that “invisible”
microbes could travel through the air to infect plants and
animals or remain on clothing and bedding to be transmitted
from one person to another. Despite these doubts scientists
gradually accumulated the information needed to support the
new germ theory.

Question 23

Joseph Lister - 1860s

Answer 23

In the 1860’s, Lister, an English surgeon, applied the germ theory to medical procedures. Lister was aware that in the 1840s, Hungarian physician Ignaz Semmelweis had demonstrated that physicians, who at the time did not disinfect their hands, routinely transmitted infections (puerperal, or child birth, fever) from one obstetrical patient to another. Lister had also heard of Pasteur’s work connecting microbes to animal diseases. Disinfectants were not used at the time, but Lister knew that phenol (carbolic acid) kills bacteria, so he began treating surgical wounds with a phenol solution. The practice so reduced the incidence of infections and deaths that other surgeons quickly adopted it. Lister’s technique was one of the earliest medical attempts to control infections caused by microorganisms. In fact, his findings proved that microorganisms cause surgical wound infections.

Question 24

Robert Koch - 1876

Answer 24

The first proof that bacteria actually cause disease came from Koch in 1876. Koch, a German physician, was Pasteur’s young rival in the race to discover the cause of anthrax, a disease that was destroying cattle and sheep in Europe. Koch discovered rod-shaped bacteria now known was Bacillus Anthracis in the blood of cattle that had died of anthrax. He cultured the bacteria on nutrients and then injected samples of the culture into healthy animals. When these animals became sick and died, Koch isolated the bacteria in their blood and compared them with the originally isolated bacteria. He found that the two sets of blood cultures contained the same bacteria

Question 25

Koch’s Postualtes

Answer 25

A sequence of experimental steps for directly relating specific microbe to a specific disease.

1. The same microorganism is present in all cases of the disease.
2. A pure culture of microorganisms is prepared from a diseased animal
3. Microorganisms from pure culture are injected into healthy animal, and same disease occurs.
4. The same microbes are recovered from the 2nd diseased animal

Question 26

Edward Jenner - 1796

Discovered first vaccine

Answer 26

On May 4, 1796, almost 70 years before Koch established that specific microbes causes anthrax, Edward Jenner, a young British physician, embarked on an experiment to find a way to protect people from smallpox.
When a young milkmaid informed Jenner that she couldn’t get smallpox because she already had been sick from cowpox–a much milder disease–he decided to put the girl’s story to the test. First Jenner collected scrapings from the cowpox blisters. Then he inoculated a healthy 8-year-old volunteer with the cowpox material by scratching the person’s arm with a pox-contaminated needle. The scratch turned into a raised bump. In a few days, the volunteer became mildly sick but recovered and never again contracted either cowpox or smallpox. The process was called VACCINATION. The protection from disease provided by vaccination (or by recovery from the disease itself) is called IMMUNITY.

Question 27

Mycology

Answer 27

The study of fungi, includes medical, agricultural, and ecological branches. Recall that Bassi’s work leading up to the germ theory of disease focused on a fungal pathogen. Fungal infection rates have been rising during the past decade, accounting for 10% of hospital-acquired infections.