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micro. chapter 6
Terms in this set (38)
only contains those compounds needed for an organism to grow
chemically defined minimal medium
rely on other organisms to make the organic compounds that they use as carbon sources
use the CO2 discarded by heterotrophs to make a complex cell constituents made up of C,H, and O, such as carbohydrates
extract energy from absorption of light
extract energy from oxidation-reduction reactions that remove electrons from high energy compounds to produce lower energy compounds : lithography, organotrophy
-a single, genetically homogeneous strain of a single species
-can be grown in a liquid or solid media
-used to examine growth rates and microbial biochemistry
-useful for spreading mixtures of different organisms
using an inoculation loop to dilute cells
Dilution in liquid culture
originate from a single cell
water, salts, carbon, nitrogen, and energy sources added in precise amounts
synthetic medium/minimal medium
-nutrient-rich but poorly defined
-yeast/beef extract, peptides, vitamins whose exact concentration and composition is not known
complex medium/rich medium
for particularly fastidious organisms, blood or blood components added to a basic complex medium
favor the growth of one organism over another
Expose biochemical differences between 2 species that grow equally well
how are bacteria counted
-dilutuons of a liquid culture can be plated directly on an agar surface
-after colonies form they are counted and the original cell number is calculated
-(number of colonies per volume plated in μl) × (1,000 μl/volume plated) × (1/dilution factor) = CFU/ml
one parent cell splitting into two equal daughter cells
-growth in which population size doubles at fixed rate (such as every 20 mins)
-plotting the increase in the number of cells over time generates an exponential curve
with unlimited resources, bacteria divide at constant interval called??
generation time/ doubling time
phases of bacterial growth?
lag, log, stationary, death
a continuous culture system in which the diluting medium contains a growth-limiting amount of an essential nutrient.
In open systems where fresh medium is continually added to a culture and an equal amount of culture is constantly siphoned off, bacterial populations can be kept in exponential phase at a constant cell mass for long periods of time.
What are the environmental limits beyond which microbes will not grow?
-depends on microbe
-Ecological niches outside the norm for humans are considered extreme.
-Every protein and macromolecular structure within a cell is affected by changes in the environment.
-Extremophiles are bacteria, archaea, and some eukaryotes that can grow in extreme environments.
can grow at temp as low as O degrees C but their optimum growth temp is around 14 degrees C
have optimal growth between 20-40 degrees C, with a minimum of 15 degrees C and Maximum of 45 degrees C
have adapted to growth at high temps, typically at 55 degrees C and higher
can grow at temps as high as 121 degrees C
organisms that have adapted to grow at high pressures are called
barophiles and piezophiles
bacteria that generally grow between pH 5 and 8 and include most human pathogens
are bacteria and archaea that live in acidic environments. They are often chemoheterotrophs that oxidize reduced metals and generate strong acids such as sulfuric acid.
occupy the opposite end of the pH spectrum, growing best at values ranging from pH 9 to pH 11.
how do you culture anaerobes
-AnaerobesAnaerobe jar (for plates) whereO2 is removed and CO2 isgenerated.
-Anaerobic chamber with gloveports that remove the atmosphere via vacuum and replace it with a precise mixture of N2 and CO2 gases.
that possess the enzymes to detoxify oxygen radicals and also the machinery for both fermentation and aerobic respiration.
use only fermentation to provide energy but contain superoxide dismutase and catalase or peroxidase to protect them from ROS.
will grow only at low oxygen concentrations. They possess a decreased level of superoxide dismutase and/or catalase.
a mass of bacteria that stick to and multiply on a solid surface, such as a stone in a lake or a lung in a cystic fibrosis patient
During the formation of a biofilm, more and more cells bind to the surface and begin to communicate with each other by sending and receiving chemical signals in a process known as??
-are resistant to many environmental stresses that kill vegetative cells.
-dessication of the spore
-packing with small acid-soluble proteins (SASPs) that bind to and protect DNA
-The SASP coat protects from damage due to UV light and various toxic chemicals.
advantage of endospores?
Once proper conditions are restored, germination is triggered that wakes up the dormant cell, dissolves the spore coat, and releases a viable vegetative cell.
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