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Lecture 3: Bacterial Anatomy and Growth


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What is flagella composed of?
flagella, which is composed of flagellin, is a gear with ____ and ___ in the membrane
rings and rod
The direction of flagellar motion determines ____ vs. _____
run vs. tumble
The number and placement of flagella vary by species. Bacteria can be ____, _____, ____, _____.
monotrichous, lophotrichous, amphitrichous, petrichous
possessing a single flagellum at one end
having a group of two or more flagella at one end
having a single or group of flagella at both ends
having flagella at many locations over the cell surface.
a movement toward a chemical attractant. It can be an attraction or repulsion.
how do flagella move in bacteria?
how do flagella move in protozoa?
What forms spores when nutrients are exhausted?
A few gram-positive bacteria, especially members of the genera Bacillus and Clostridium
Spores contains very little water and use lots of ___ to stabilize proteins and DNA.
dipicolinic acid
spores become _____ as soon as favorable conditions return
what three things can spores survive?
1) boiling water
2) Ethanol
3) Radiation.

*Spore have been found in mummies & fossils
What are the steps of binary fission?
- Chromosome duplicates
- Cell elongates
- Plasma membrane moves inward to make 2 cells
the interval of time between successive binary fissions of a cell or population of cells (a.k.a. doubling time)
generation time
What is Escherichia coli's generation time?
20 minutes
What is Staphylococcus aureus's generation time?
30 minutes
What is Mycobacterium tuberculosis's generation time?
18 hrs
What is treponema pallidum's gneration time?
22 hrs
What are the four distinct phases of a typical bateria growth curve?
- lag phase
- exponential growth phase
- stationary phase
- death phase
Lag phase
the phase of a bacterial growth curve prior to binary fission. No cell divisions occur.
exponential growth phase (also known as logartithmic phase)
the phase of a bacterial growth curve when reproduction and growth are at their highest rates. all cells are undergoing binary fission. As each generation time passes, the number of bacteria doubles and the graph rises in a straight line on a logarithmic scale
Stationary phase
The phase of a bacterial growth curve when the reproduction rate equals the death rate.
death phase (also known as decline phase)
the number of dying cells exceeds the number of new cells formed.
What are three important factors governing growth?
- Temperature
- Oxygen
- pH
Bacteria have different ideal growth temperatures. Psychrophiles grow at what temperature range?
psychrophiles like the cold
Mesophiles grow at what temperature range?
-ex: pathogens that grow in the human body
Thermophiles grow at what ideal temperature range?
Hyperthermophiles grow at what ideal temperature range?
90 up to 113°C
Most pathogenic bacteria prefer temperatures of 35-42°C, making them ___
psychrotropic or psychrotolerant bacteria
-can grow below normal range (still alive in the fridge)
-mesophiles that grow in the cold.
-They are not truly psychrophilic. They will survive at 0°C but prefer to grow at typical mesophile temperatures.
aerobic bacteria
bacteria that depends on a plentiful supply of oxygen
anaerobic bacteria
bacteria that live in oxygen-free environment, may die in presence of oxygen
-ex: Clostridium botulinum
facultative bacteria
Can grow either in presence of or reduced concentration of oxygen (majority of bacteria)
Microaerophilic bacteria
requires low oxygen to grow
-Ex: T. pallidum
Capnophilic bacteria
low oxygen and high carbon dioxide required
-ex: Neisseria, Streptococcus)
What is the pH range of bacteria?
What is the preferred pH range of bacteria?
- Human blood and tissue, perfect hosts
Most bacteria do not grow well in: a) acid or b) base?
- Stomach acid deters bacteria
- Citrus fruits rarely contaminated w/ bacteria. molds instead!
acid-tolerant and useful for food/dairy industry
-Ex: Lactobacillus, Streptococcus
What is most bacteria grown on?
some type of protein nutrient broth w/ agar added
What is added to solidify the protein nutrient broth that most bacteria grow on?
Enriched media
contains special nutrients for fastidious bacteria
- Ex: Neisseria grow on chocolate agar- heated whole blood (hemoglobin)
Selective media
allows growth of certain bacteria while inhibiting others
Differential media
distinguishes one type of bacteria from another

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