Extra questions for microbio exam 1 Flashcards
Salt has been used as a preservative through the production of “salted” fish or pork. Indicate all of the correct (true) statements below regarding high salt environments.
sensitive (non-halophilic) bacteria will lose water (shrink) in high salt environments
Of all environmental organisms, it is estimated that _____ are cultivable in the laboratory.
<5%
The production of a biofilm is an example of ___________ between normally independent species.
synergy
The methanogens, producers of methane gas, require environments that:
are anaerobic with hydrogen gas and CO2.
Detection and quantification of bacterial species in complex populations (i.e. in the soil) can best occur using which method?
Genetic (DNA) detection
This is because it allows for identification and quantification of specific bacterial species in complex samples like soil
The generation time for bacterial growth……
will vary depending on the bacterial species and growth conditions
is calculated during the log phase of bacterial growth
represents the time it takes for 1 bacterium to divide into two
In the log (exponential) phage of growth, 10 bacteria with a generation time of 20 minutes would produce _____ bacteria in 1 hour. (Hint: This question is asking for Nt)
The equation is Nt = N0 * 2^n
80
You divide an hour by 20
so
10^3
20
40
80 final result
facultative anaerobes:
they can live without oxygen, but grow better with it
they possess enzymes that detoxify oxygen-based free radicals
they include a large number of commenal and pathgenic bacterial species
In general, what must be secreted by bacteria to extract nurtrition from organic polymers in the environment?
enzymes
Large polymers (i.e. of carbohydrate or protein) can be utilized as nutrients by bacteria…..
Which nutrient (element) may be included in amino acids but is not required in nucleic acids (ie. RNA/DNA)?
Sulfur
Which of the following molecules is the most abundant in the prokaryotic cell?
water
Germ Theory of Disease and its Relationship to Microscopy, Spontaneous Generation, Fermentation, and Koch’s Postulates:
Definition: The Germ Theory of Disease is the scientific concept that many diseases are caused by microorganisms such as bacteria, viruses, fungi, and parasites. It proposes that these microorganisms can infect and multiply within a host, leading to illness.
Microscopy: Advancements in microscopy, particularly the development of high-powered microscopes in the 17th century, allowed scientists to observe microorganisms for the first time. Anton van Leeuwenhoek’s observations of bacteria and protozoa laid the foundation for the Germ Theory.
Spontaneous Generation: Prior to the Germ Theory, there was a widely held belief in spontaneous generation, the idea that life could spontaneously arise from non-living matter. This theory was debunked through experiments by Louis Pasteur, which supported the notion that microorganisms were responsible for contamination.
Fermentation: The study of fermentation by scientists like Pasteur helped establish the role of microorganisms in metabolic processes. Pasteur’s work on yeast fermentation demonstrated that specific microorganisms were responsible for the transformation of substrates.
Koch’s Postulates: Developed by Robert Koch, these postulates provided a framework to definitively link a specific microorganism to a particular disease. They include isolating the microorganism from a diseased host, cultivating it in pure culture, reintroducing it to a healthy host, and observing disease development. Koch’s work greatly strengthened the Germ Theory.
Microbial Contamination in Body Samples and Lab Techniques:
Various body locations are susceptible to microbial contamination, known as the “haystack” in microbiology. These contaminants can confound clinical diagnoses or research results.
Appropriate lab techniques involve aseptic (sterile) procedures to prevent contamination. These include using laminar flow hoods, sterilizing equipment, and maintaining clean environments.
Culture media are essential for isolating, identifying, and enriching pathogens. General media types include agar plates for isolation, selective media to encourage growth of specific pathogens, and enrichment media to increase pathogen numbers.
Peptidoglycan and Outer Membrane Structure
Peptidoglycan: Found in bacterial cell walls, peptidoglycan is a rigid polymer made of sugars (glycan) and amino acids (peptide). It provides structural support to the cell wall.
Outer Membrane: Present in Gram-negative bacteria, the outer membrane is an additional lipid layer outside the peptidoglycan. It contains porins and lipopolysaccharides (LPS), which contribute to the cell’s permeability and resistance to certain antibiotics.
Implications for Gram Positive and Negative Bacteria: Gram-positive bacteria have a thick peptidoglycan layer but lack an outer membrane. Gram-negatives have a thin peptidoglycan layer sandwiched between two membranes (inner and outer).
Cell Wall Inhibitors: Antibiotics like penicillin target peptidoglycan synthesis. Gram-negative bacteria are often more resistant to antibiotics due to their outer membrane.
Common Bacterial Structures: Common structures include cell membranes, ribosomes, flagella, and cytoplasm. Capsules and pili are used for identification and can facilitate disease as virulence factors.
