Chapter 1 Flashcards
Science is the study of?
Nature that proceeds by posing questions about observations
Who is Antoni van Leeuwenhoek?
A dutch tailer, merchant, and lens grinder, and the man who first discovered the bacterial world
Leeuwenhoek reported the existence of what in 1674 and what in 1676? Why the years difference?
1674 he reported protozoa
1676 he reported bacteria
Protozoa are generally larger than bacteria
A system for naming plants & animals and grouping similar organisms together
Taxonomic system
Who developed a taxonomic system?
The swedish botanist Carolus Linnaeus
The microorganisms that Leeuwenhoek described can be grouped into 6 basic categories
The only type of microbes not described is?
1) Bacteria
2) Archaea
3) Fungi
4) Protozoa
5) Algae
6) Small multicellular animals
* Viruses are not described
Bacteria & archaea are both what?
Prokaryotic meaning that they lack nuclei; that is there genes are not surround by a membrane
Bacterial cell walls are composed of a polysaccharide called?
Archaea cell walls are?
Peptidoglycan (some bacteria however, lack cell walls)
Archaea cell walls lack peptidoglycan and instead are composed of other chemicals
How do bacteria and archaea reproduce?
Asexually
Where is archaea often found?
In extreme environments, such as the highly saline Mono Lake in California, acidic hot springs in Yellowstone National Park, & oxygen depleted mud at the bottom of swamps
True or False: No archeae are known to cause disease?
True
Fungi cells are?
Eukaryotic, that is, each of their cells contains a nucleus composed of genetic material surrounded by a distinct membrane
How are fungi different from plants? From animals?
Fungi obtains their food from other organisms (rather than making it for themselves).
They differ from animals by having cell walls
Some molds and yeasts are examples of?
Fungi
1) What are molds?
2) How do they reproduce?
1) Typically multicellular organisms that grow as long filaments that intertwine to make up the body of the mold
2) Sexual and asexual spores, which are cells that produce a new individual without fusing with another cell
A mold that produces penicillin
Penicillium chrysogenum
1) Yeasts are?
2) How do they reproduce?
1) Unicellular & typically oval to round.
2) Asexually by budding, a process in which a daughter cell grows off the mother cell. Some also produce sexual spores
Causes bread to rise and produces alcohol from sugar
Saccharomyces cervisiae (useful yeast)
Yeast that causes most cases of yeast infection in women
Candida albicans
What are protozoa?
Single celled eukaryotes that are similar to animals in their nutritional needs & cellular structure
Most protozoa are capable of locomotion, one way scientists categorize protozoa is according to their locomotive structures which are?
1) Pseudopodia
2) Cilia
3) Flagella
Protozoa that are pseudopodia are?
Extensions of a cell that flow in the direction of travel
Protozoa that are cilia are?
Numerous, short protrusions of a cell that beat rhythmically to propel the protozoan through its environment
Protozoa that are flagella are?
Extensions of a cell, but are fewer, longer, & more whiplike than cilia
Malaria-causing protozoa, non motile in their mature forms
Plasmodium
Where do protozoa live?
Freely in water, but some live inside animal hosts, where they can cause disease
Most protozoa reproduce…
Asexually, though some are sexual as well
What is algae?
Unicellular or multicellular photosynthetic organisms; that is, like plants they make their own food from carbon dioxide & water using energy from sunlight
How does algae differ from plants?
They differ from plants in the relative simplicity of their reproductive structures
Algae are categorized on the basis of their?
Pigmentation & the composition of their cell walls
Unicellular algae are common in?
Freshwater ponds, streams, and lakes, and in the oceans as well. They are the major food of small aquatic & marine animals & provide most of the worlds oxygen as a byproduct of photosynthesis
The only type of microbe that remained hidden from Leeuwenhoek and other early microbiologists was?
Viruses, which are much smaller than the smallest prokaryote and are not visible by light microscopy
Viruses could not be seen until?
The electron microscope was invented in 1932
All viruses are?
Acellular (not composed of cells) obligatory parasites composed of small amounts of genetic material (either DNA or RNA) surrounded by a protein coat
Many philosophers & scientists of past ages thought that living things arose via three processes
1) Through asexual reproduction
2) From nonliving matter
3) Abiogenesis or spontaneous generation
Describe Francesco Redi’s, the italian physician, experiments
He demonstrated with a series of experiments that when a decaying meat was kept isolated (away) from flies maggots would never develop. The meat that was exposed to flies however was soon infested with maggots.
The proponents of spontaneous generation pointed to the careful demonstrations of British investigator John T. Needham, what did he do?
He boiled beef gravy and infusions of plant material in vials, which he tightly sealed with corks. Days later he observed that the vials were cloudy and an examination revealed an abundance of microscopial animals of most dimensions. He thought that there must be a life force that causes inanimate matter to spontaneously come to life, because he had heated the vials to kill everything
How does the italian scientist Lazzaro Spallanzani results differ from those of Needhams?
Spallanzani boiled infusions for almost an hour & sealed the vials by melting their slender necks closed. The infusions remained clear, unless he broke the seal and exposed the infusion to air which they then became cloudy with microorganisms, he concluded 3 things:
1) Needham had either failed to heat his vials sufficiently to kill all microbes, or he had not sealed them tight enough
2) Microorganisms exist in the air & can contaminate experiments
3) Spontaneous generation of microorganisms does not occur; all living things arise from other living things
Describe Louis Pasteur’s experiments
Like Spallanzani, he boiled infusions long enough to kill everything, but instead of sealing the flasks, he bent their necks into an S shape, which allowed air to enter while preventing the introduction of dust & microbes into the broth. They remained free of microbes even 18 months later. Because his experiments were exposed to air but not dust he concluded that Needham’s experiments were exposed to dust in the air which he said to be the parents of Needham’s microorganisms.
The 4 basic steps of the scientific method
1) A group of observations leads a scientist to ask a question about some phenomenon
2) The scientist generates a hypothesis- that is a potential answer to the question
3) The scientist designs and conducts an experiment to test the hypothesis
4) Based on the observed results of the experiment, the scientist either accepts, rejects, or modifies the hypothesis
Accepted hypotheses that explain many observations & are repeatedly verified by numerous scientists over many years are called?
Theories or laws
For the scientific community to accept experiments (and their results) as valid, they must include?
Appropriate control groups
Considered the father of microbiology. Why?
Pasteur because of his many, varied, and significant accomplishments in working with microbes
Scientists in the 1800s used the word fermentation to mean?
Not only the formation of alcohol from sugar, but also other chemical reactions such as the formation of lactic acid, the putrefaction of meat, and the decomposition of waste
Pastaur conducted a series of careful observations & experiments that answered the question, “What causes fermentation?” What were his observations?
He observed yeast cells growing and budding in grape juice & conducted experiments showing that they arise only from other yeast cells. By sealing some sterile flasks containing grape juice & yeast, & by leaving others open to the air, he demonstrated that yeast could grow with or without oxygen. By introducing bacteria and yeast cells into different flasks of sterile grape juice, he proved that bacteria ferment grape juice to produce acids & that yeast cells ferment grape juice to produce alcohol
Organisms that can live with or without oxygen
Facultative anaerobes
What is pasteurization?
A process of heating the grape juice just enough to kill most contaminating bacteria without changing the juice’s basic qualities, so that it could then be inoculated with yeast to ensure that alcohol fermentation occurred
Pasteur began the field of industrial microbiology (or biotechnology) meaning?
Which microbes are intentionally used to manufacture products
Today pasteurization is used to?
Used routinely on milk to eliminate pathogens that cause such diseases os bovine tuberculosis and brucellosis; it is also used to eliminate pathogens in juices and other beverages
Whose work began the field of biochemistry and the study of metabolism?
The german scientist Eduard Buchner
Prior to the 1800s, disease was attributed to various factors including
Evil spirits, astrological signs, imbalances in body fluids, and foul vapors
Pasteurs discovery that bacteria are responsible for spoiling wine led naturally to his hypothesis in 1857 which was?
That microorganisms are also responsible for diseases. This idea came to be known as the germ theory of disease
Because a particular disease is typically accompanied by the same symptoms in all affected individuals, early investigators suspected that diseases are each caused by?
A specific germ, called a pathogen
Today we know that some diseases are genetic and that allergic reactions and environmental toxins cause others, so the germ theory applies only to?
Infectious diseases
The study of causation of diseases
Etiology
Just as Pasteur was the chief investigator in disproving spontaneous generation and determining the cause of fermentation, so investigations in etiology were dominated by?
Robert Koch
Robert Koch was instrumental in modifying what?
The scientific method to prove that a given pathogen caused a specific disease
After Koch discovered Anthrax he continued to search for disease agents. He announced that the cause of tuberculosis was a?
Rod-shaped bacterium, Mycobacterium tuberculosis. In 1905 he received the Nobel Prize in Physiology for Medicine for this work
What is Koch’s postulates?
Steps that must be taken to prove the cause of any infectious disease
What are the steps of Koch’s postulates?
1) The suspected causative agent must be found in every case of the disease and be absent from healthy hosts
2) The agent must be isolated and grown outside the host
3) When the agent is introduced to a healthy, susceptible host, the host must get the disease
4) The same agent must be found in the diseased experimental host
We use the term suspected causative agent because
It is merely suspected until the postulates have been fulfilled, and agent can refer to any fungus, protozoan, bacterium, virus, or other pathogen
Though Koch reported a simple staining technique in 1877, the Danish scientist Hans Christian Gram developed a more important staining technique. What was his technique?
His procedure involves the application of a series of dyes, leaves some microbes purple and others pink. We now label the first group of cells as Gram-positive and the second as Gram-negative, and we use the Gram procedure to separate bacteria into these two large groups
Which stain is still widely used?
The Gram stain is. It is one of the first steps carried out when bacteria are being identified.
Infections acquired in a health care setting
Nosocomial infections
Who was Florence Nightingale?
The founder of modern nursing, she was influential in introducing antiseptic technique into nursing practice
Today we know the primary cause of puerperal fever is a?
Bacterium in the genus Streptococcus which is usually harmless on the skin or in the mouth but causes severe complications when it enters the blood
What did Ignaz Semmelweis do?
He was a physician on the obstetric ward. He hypothesized that medical students carried cadaver particles from their autopsy studies into the delivery rooms and that these particles resulted in puerperal fever. He began requiring that medical students wash their hands with chlorinated lime water
What did the English physician Joseph Lister do?
He modified and advanced the idea of antisepsis in health care settings. He would spray wounds, surgical incisions and dressings with carbolic acid
Became the founder of antiseptic surgery, and opened new fields of research into antisepsis and disinfection
Joseph Lister
Who is Florence Nightingale and what did she do?
She was a English nurse who introduced cleanliness and other antiseptic techniques into nursing practice. She was instrumental in setting standards of hygiene that saved innumerable lives during the Crimean War. One of her first requisitions in the military hospital was for 200 scrubbing brushes. She then arranged for each patients filthy clothes and dressing to be replaced or cleaned at a different location, thus removing many sources of infection
What did the English physician John Snow do?
He studied the propagation of cholera and suspected the disease was spread by a contaminating agent in water. His study was the foundation for two branches of microbiology- infection control and epidemiology, which is the study of occurrence, distribution, and spread of disease in humans
What did the English physician Edward Jenner do?
He tested the hypothesis of cowpox could provide protection against potentially fatal smallpox. He inoculated a boy with puss collected from a milkmaid’s cowpox lesion. The boy got cowpox and survived. He then infected the boy with smallpox pus and found that the boy was immune to smallpox. He went on to test this hypothesis and he named the procedure vaccination after Vaccina virus, the virus that causes cowpox.
Who invented vaccination (also called immunization), and established a safe treatment for preventing smallpox, and began the field of immunology
English physician Edward Jenner
Define immunology
The study of the body’s specific defense against pathogens
In honor of Edward Jenner’s work with cowpox, Pasteur used to term vaccine to refer to?
All weakened, protective strains of pathogens. He subsequently developed successful vaccines against fowl cholera, anthrax, and rabies.
Gram’s discovery that stained bacteria could be differentiated into two types suggested to the German microbiologist Paul Ehrlich that chemicals could be used to?
Kill microorganisms differentially. He undertook an exhaustive surgery of chemicals to find a “magic bullet” that would destroy pathogens while remaining nontoxic to humans. He had discovered chemicals active against the protozoan parasites that cause sleeping sicknesses and against the causative agent of syphilis.
The German microbiologist Paul Ehrlich discoveries began the branch of medical microbiology known as?
Chemotherapy
The Golden Age of Microbiology was a time when?
Researchers proved that living things come from other living things, that microorganisms can cause fermentation and disease, and that certain procedures and chemicals can limit, prevent, and cure infectious diseases.
What is biochemistry?
The study of metabolism-that is, the chemical reactions that occur in living organisms.
When did biochemistry begin?
With Pasteur’s work on fermentation by yeast and bacteria and with Buchner’s discovery of enzymes in yeast extract, but by the early 1900’s many scientists thought that the metabolic reactions of microbes had little to do with the metabolism of plants & animals
Basic biochemical research has many practical applications, including:
1) Design of herbicides & pesticides specific in their action & have long term adverse effects on the environment
2) Diagnosis of illnesses & monitoring of patient’s responses to treatment
3) Treatment of metabolic diseases
4) Design of drugs to treat leukemia, gout, bacterial infections, malaria, AIDS, asthma, and heart attacks
What is genetics?
The scientific study of inheritance
When did genetics start?
It started in the mid 1800s as an offshoot of botany, but scientists studying microbes made most of the great advances in this discipline
While working with the bacterium Streptococcus pneumoniae, what did Oswald Avery, Colin MacLeod, and Maclyn McCarty determine?
They determined that genes are contained in molecules of DNA
Working with bread mold Neurospora crassa, what did George Beadle and Edward Tatum establish?
They established that a gene’s activity is related to the function of the specific protein coded by that gene.
What is molecular biology?
Combines aspects of biochemistry, cell biology, and genetics to explain cell function at the molecular level.
Molecular biologists are concerned with genome sequencing, which is?
Using techniques perfected on microorganisms, molecular biologists have sequenced the genomes of many organisms including humans and many other pathogens.
The american nobel prize winner Linus Pauling proposed in 1965 that gene sequences could provide a means of understanding?
Evolutionary relationships & processes, establishing taxonomic categories that more closely reflect these relationships, & identifying the existence of microbes that have never been cultured in a laboratory
What are 2 examples of the use of gene sequencing in date
1) Carl Woese discovered that significant differences in nucleic acid sequences among organisms clearly reveal that cells belong to one of 3 major groups- bacteria, archaea, or eukaryotes
2) Scientists showed in 1990 that cat scratch disease is caused by a bacterium that could not be cultured. The bacterium was discovered by recognized the sequence of a portion of its ribonucleic acid sequences
Molecular biology is applied in recombinant DNA technology, commonly called genetic engineering, which was first developed using?
Microbial models
Geneticists manipulate genes in microbes, plants, & animals for practical applications. For instance, once scientists have inserted the gene for human bloodletting factor into the bacterium Escherichia coli, the bacterium produces the factor in?
Pure form. This technology is a boon to hemophiliacs, who previously depended on clotting factor isolated from donated blood, which was possibly contaminated by life-threatening viral pathogens
A new area of study is the use of recombinant DAN technology for gene therapy which is?
A process that involves inserting a missing gene or repairing a defective one in human cells. In such procedures, researchers insert a desired gene into host cells, where it is incorporated into a chromosome & begins to function normally.
Define bioremediation
The use of living bacteria, fungi, and algae to detoxify polluted environments
Microbial communities also play an essential role in the decay of dead organisms and the recycling of chemicals such as?
Carbon, nitrogen, and sulfur
What did Martinus Beijerinck discover?
Bacteria capable of converting nitrogen gas from the air into nitrate, the form of nitrogen used by plants, & the Russian microbiologist Sergei Winogradsky elucidated the role of microorganisms in the recycling of sulfur
Together these two microbiologists developed laboratory techniques for isolating & growing environmentally important microbes
Martinus Beijerinck and Sergei Winogradsky
How can the germ theory explain why some people get sick during the flu season while their close friends and family remain well?
The germ theory of disease showed not only that microorganisms can cause diseases, but also that the body can defend itself
Define serology
The study of blood serum
Ehrlich introduced the idea of a “magic bullet” that would kill pathogens, but it wasn’t until Alexander Fleming discovered what? And Gerhard Domagk discovered? That medical personnel finally had drugs effective against a wide range of bacteria
Alexander Fleming discovered- Penicillin in 1929
Gerhard Domagk discovered- sulfa drugs in 1935
