Flashcards in Chapter 4 Deck (56):
A) How does the process of binary fission work? [Figure 4.1 and Binary Fission video]
Cell multiplies it’s components and then divides in two. Then those to divide and so on and so forth
B) How can you calculate exponential growth? [Table 4.1
Equation: Nt= No X 2^N or populations at a given time =original # in a population times 2 to the number of divisions
1) What is the generation time?
The time it takes bacteria to double in population.
A) What are biofilms? How do they form? [Figure 4.2, 4.3 and Biofilm Formation video]
Polymer encased community of prokaryotes. Cell attaches so a surface using a extracellular polymeric substance. This is made of polysaccharides,dna and other hydrophilic polymers.
B) How can different species of bacteria in the same environment help each other?
Some live next to the others that create the environment that they need ie. Some bacteria thrive on O2 and so some who cannot live with O2 will live with them. Also some eat the waste of others.
A) What is a pure culture?
A population descended from a single cell.
B) What is the aseptic technique?
Proceedures that prevent the chance of other organisms being accidently introduced
C) How is a colony formed? [Figure 4.4]
D) What is agar and where is it used?
Polysaccharide extracted from marine algea used to solidify a culture media. In peri dish
E) How do you do a streak-plate? [Figure 4.5]
F) How can a stock culture be maintained?
Stock culture: saved pure culture for later use. Can be stored in a slant. Oor frozen in a glycerol solution at -70 degrees Celsius. Or cells can be freeze dried
A) What are batch cultures?
Bacteria left in a container is called a closed system= batch culture because it had limited nutrients, and no wastes are reserved.
B) What is an open system or continuous culture?
Continually added nutrients and waste products removed
C) What does a growth curve show? [Figure 4.6]
Map of a certain cells population.
2) What happens during the exponential or log phase?
Cells divide at a constant rate
- What are primary and secondary metabolites? [Figure 4.7]
1) What happens during the lag phase?
Cell number does not immediately increase cell begins to systhesize enzymes required for growth.
3) What happens during the stationary phase?
When nutrients start to wain and is unable to sustain the population. So growth stops.
3) What happens during the death phase?
Cells die and so the population drops
4) What happens during the phase of prolonged decline?
Cells that survived death phase, but die off
E) What is a chemostat?
Device that allows drops of cells and nutrients etc. and then allows an equivalent volume to leave/ drain out, keeping a constant population size. This is so you can see a populations response to a certain environment.
D) How does microbial growth differ between liquid and solid mediums?
In solid the cells have equivalent environment. In cells in a liquid have to fight for the preferred environment.
A) What are extremophiles? [Table 4.2]
B) What are the temperature requirements for growth and how is that used to group bacteria?
Psychrophiles: -5 - 15
Hyperthermophiles: 70 or greater
C) How does refrigeration keep foods from going bad?
limit multiplication of fast growing mesophiles
D) How does the differing temperature of the body influence disease?
depending at part of the body the area a disease may prefer and tend to infect ie. leporacy and extremities
E) What groups are bacteria separated in based on their oxygen requirements? [Table 4.3]
aerobic and anaerobic
F) What is a reactive oxygen species?
are harmful substances that result from aerobic respiration breakdown. such as o2 radicals and hydrogen peroxide
G) What do the enzymes superoxide dismutase and catalase do?
superoxide: takes o2 and turns into h2o2 and then
Catalase: take h2o2 into h2o and water
H) How are bacteria grouped based on what pH they grow in?
Neutrophiles: 5-8 ph food and people
Acidphiles: 5.5 below(volcanic fissures)
Alkiphiles: 8.5 and up(lakes and soils)
I) What is plasmolysis? [Figure 4.9]
when a cell is placed in hypertonic solution and cytoplasm dehydrates from cell wall
J) What are halotolerant, halophiles, and extreme halophiles?
Halotolerant: salt tolerant up to 10% nacl
Halophiles: requires at least 3% and need nacl
Extreme: require 9%
A) What major elements make up a cell? [Table 4.4]
B) What are the differences between heterotrophs and autotrophs?
hetero: use organic c
auto: use inorganic C, usually in form of co2
C) How is carbon and nitrogen fixation done and why is it important?
Carbon fixation: takes inorganic and turns it into organic. If they did not we would quickly run out of organic carbon
Nitrogen Fixation: Takes N and converts it into ammonia which is then incorperated into cellular material.
D) What are limiting nutrients?
available at lowest concentrations relative to need. This limits the maximal level of microbial growth. phosphorus and iron
E) What are trace elements?
element required in such small amounts that most natural environments, inclueding water have enough to support microbial growth. Cobalt, zinc, copper, maganese
F) What are growth factors?
rely on a molecule that the cell itself cannot produce. This leads to it relying on environment to provide it. The molecule is refered to as a growth factor.
G) What makes an organism fastidious?
have complicated nutritional required
H) How are bacteria divided based on the energy and carbon sources they use? [Table 4.5]
e source, then carbon source
Photoheterotrophs:sunlight organic compounds
Chemolithautotrophs: inorganic chem co2
chemoorganoheterotrophs:organic compounds organic comp.
A) Review table 4.6
B) What are complex medium and what are they used for?
contain a vareity of ingredients. used for routine purposes
C) What are chemically defined media and what are they used for? [Table 4.7]
Chemically defined media is composed of exact amounts of pure elements. used in expiriments when the type and quantity have to be controlled.
D) What are selective media and what are they used for?
They provide an environement only specific bacteria can survive.
E) What are differential media and what are they used for? [Figure 4.10]
They are used to determine the type of diff bacteria.
contain substances that certain microbes change in a recognizable way.
A) Review table 4.8
B) What is direct microscopic counting used for and how is it done? [Figure 4.15]
slide holds a specific volume and has a microscopic grid.
C) What is a Coulter counter and a flow cytometer? [Figure 4.16]
An electronic instrument that counts cells in suspension as they pass single file through a narrow chamber.
Flow:counts light scattered by cells as they pass through a lazer
D) How and why is a plate count done? [Figure 4.17]
count the colonies to know how many original cells there were.
1) What are the differences between the pour plate and spread plate methods? [Figure 4.18]
.1 mls is spread on the surface of a agar plate.
pour is they take.1-1 mls of sample and transfered to a petri dish and then it is overlaid with a melted agar
E) What are CFU’s?
colony forming units: ?
F) What is membrane filtration used for? [Figure 4.19]
is used for liquid samples that are dilute and poured through a filter then the filter is put on a meduim and then you observe the growth.
G) What is the most probable number method used for? [Figure 4.20]
used to estimat the concentration of cells in a specimen.
uses series of dilutents until it is determined the subsequent dilutent
H) What is turbidity and how is it used? [Figure 4.21]
cloudines- is proportional to the concentration of cells and is measured with a spectrophotometer ( sends a light through a specimen and measures the percentage of light that reaches a detector. this is inversely proportional to optical density. helps you know how many cells and the density in a specific specimen.
I) How can you use the total weight of a culture to determine growth?
usually used to determine count of cells 102. take wet weight and dry weight to determine cell growth.