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After disease determined to be caused my microorganisms, people focused on __
destroying pathogenic microbes
Treatment of disease by using chemical substances is called __
Chemicals produced naturally by bacteria and fungi to act against other microorganisms are called __
Chemotherapeutic agents prepared from chemicals in the lab are __
The microorganism is more poisoned by the chemical than the microbes
- synthetic drugs
- speculated about a “magic bullet” that could hunt down and destroy a pathogen without harming the infected host
- i. He found a chemotherapeutic agent called salvarsan, an arsenic derivative effective against syphilis
1930s: researchers developed several other __ that could __, which were __
How did this come about?
In addition, __
were synthesized at about the same time
- synthetic drugs
- destroy microorganisms
- derivatives of dyes
This came about because the dyes synthesized and manufactured for fabrics were routinely tested for antimicrobial qualities by microbiologists looking for a “magic bullet”
In contrast to the __, the first antibiotic was discovered by accident by __, who looked at __.
- sulfa drugs
- Alexander Fleming
- culture plates that were contaminated by mold
Explain Fleming's experience?
i. The curious growth pattern showed that around the mold was a clear area where bacterial growth had been inhibited
The mold inhibited bacterial growthà Penicillium notatum
- a. The mold’s active inhibitor was penicillin, which is an antibiotic produced by fungus
Problems with antibiotics
Many antimicrobial chemicals are too toxic to humans; and, this toxicity to humans is a particular problem in the development of drugs for treating viral diseases
- 2) Emergence and spread of new strains of microbes due to resistance to antibiotics, which results from genetic changes in microbes that enable tolerance to develop
Viral growth depends on life processes of normal host cells; thus, there are very few successful antiviral drugs because __
a drug that would interfere with viral reproduction would also likely affect uninfected cells of the body
Ex: a microbe might do what?
, or a microbe might undergo __ that prevent an antibiotic from attaching to it or entering it
- produce chemicals (enzymes) that inactivate antibiotics
- changes to its surface
the study of fungi, includes medical, agricultural, and ecological branches
i. Previously unknown parasitic diseases have been found in patients with what characteristic?
is the study of protozoa and parasitic worms
whose immune systems have been suppressed by organ transplants, cancer chemo, or AIDS
These three studies are going through a “golden age” of classification due to recent advances in __
, the study of all of an organism’s genes, which allowed scientist to do what?
classify bacteria and fungi according to their genetic relationships with other bacteria, fungi, and protozoa
, the study of immunity, dates back in Western culture to ___
- Jenner’s first vaccine in 1796
1960: __, substances generated by the body’s own immune system, were discovered
These inhibit __
- replication of viruses
, the study of viruses, originated during the Golden Age of Microbiology
1892: Dmitri Iwanowski did what?
- reported that the organism that caused mosaic disease of tobacco was smaller than a bacteria but not sure what
Recombinant DNA technology's origins can be found in two related fields.
What are they and explain them?
- 1. Microbial genetics studies the mechanisms by which microorganisms inherit traits
- Molecular biology specifically studies how genetic information is carried in molecules of DNA and how DNA directs the synthesis of proteins
1930s: research on plants and animals
1940s: scientists turned to __. Why?
- unicellular organisms
- 1. Bacteria are less complex than plants and animals
- 2. The life cycles of many bacteria last less than an hour
1941: George W. Beadle and Edward L. Tatum __, which was established as the hereditary material in 1944 by __
- demonstrated the relationship between genes and enzymes
- Oswald Avery, Colin MacLeod, and Maclyn McCarty
True or False: All diseases are caused by microscopes.
False: not all
What did Koch demosntrate?
certain bacteria were always resent in the blood of animals with a disease and were not present in healthy animals. But, the mere presence of microorganisms does not prove they caused the disease
Koch showed that __
a specific infectious disease is caused by a specific microorganism that can be isolated and cultured on artificial media
- 1. The same pathogen must be present in every case of the disease
- 2. The pathogen must be isolated from the diseased host and grown in pure culture
- 3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible lab animal
- 4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism
a. Exceptions to Koch's postulates
Some microbes have unique culture requirements, such as virulent strains, which have never been cultured on artificial media
These exceptions led to modifications and the use of alternative methods for ___ and __ certain microbes
culturing and detecting
Example of a modification?
When researchers looking for the microbial cause of legionellosis were unable to isolate it from the victim, they inoculated a victim’s lung tissue into guinea pigs and developed the disease’s pneumonia-like symptoms; those injected with unafflicted tissue did not develop the system
- 1. Then, tissue samples from the diseased guinea pigs were cultured in yolk sacs of chick embryos, a method that reveals the growth of really small microbes
- 2. After incubation, EM revealed rod-shaped bacteria in the chick embryos
- 3. Finally, modern immunological techniques were used to show that the bacteria in the chick embryos were the same bacteria that infected the pigs
Example 2: In a number of situations, a human host exhibits certain signs and symptoms associated only with __. For those that do not, such as nephritis, which can involve several different pathogens, which cause the same signs and symptoms, there is another exception
a certain pathogen and its disease
Example 3: Another exception results because some pathogens, such as Mycobacterium tuberculosis, do what?
When clinical signs and symptoms are used together with lab methods, they can be distinguished
can cause several disease conditions
What is an ethical consideration?
some agents that cause disease have no other known host, posing the question whether humans can be intentionally inoculated with infectious agents