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.