Summary
Summary BIO 175 Exam 2 Study Guide
- Course
- BIO 175
- Institution
- Wake Technical Community College
This is a comprehensive and detailed study guide on Exam 2 for Bio 175. An Essential Study Resource!!
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Chapter Six1. What atomic elements are required for microbial growth? (Top 6)
● Carbon
● Hydrogen
● Nitrogen
● Oxygen
● Phosphorus
● Sulfur
2. Understand the following terms:
Name Definition
Chemotroph Use inorganic materials for energy and carbon dioxide for carbon
Phototroph uses sunlight as energy source
lithoautotrophs microbe which derives energy from reduced compounds of mineral
origin
saprobes feed off of dead and decaying matter; secrete digestive enzymes
which breakdown living matter into small molecules so they can then
transport it inside their cytoplasm where the microbial cell can then
use them.
ectoparasites live within the host ex. blood stream infection
endoparasites live on the surface of the host
Intracellular parasites inside the actual host cells
Obligate parasite Require something to be able to survive (inside host, oxygen, etc.)
Photoautotroph uses sunlight for energy and carbon dioxide for carbon
Chemoautotroph inorganic energy source and carbon dioxide as carbon source
Photoheterotroph sunlight for energy and organic carbon sources
Chemoheterotroph chemicals for energy and organic source of carbon
3. Understand osmosis and how water moves across a semi-permeable membrane. Know the
effects isotonic, hypertonic, and hypotonic environments have on a bacterial cell. What is
plasmolysis and when does it occur?
Osmosis: diffusion of water across a semi-permeable membrane. Selectively permeable
membrane allows free diffusion of water, but blocks other molecules (salt, sugar). Water will
,move from area of lower concentration to an area of higher concentration to dilute concentrated
area.
Plasmolysis: When water leaves the cell. Results in membrane shrinking and morphing.
Hypotonic Isotonic Hypertonic
● Concentration of ● Solutes equal outside ● Concentration of
solutes outside cell is and inside cell, so solutes inside cell
lower than solutes in water moves at equal higher than outside
cytoplasm rates ● Water will be drawn
● Water will rush into ● Water will not build up into environment
cell because it is on either side of cell ● Plasmolysis
drawn to higher ● Stable environment ● Salt will draw water
concentration out of microorganisms
● Without a cell wall, too on food
much water will rush ● Halobacteria adapted
into cell=lysis to live in high salt
● Slightly hypotonic can environment, absorb
be favorable for salt to make
bacterial cells cytoplasm more
because water keeps isotonic with
cell full and rigid environment
● Water vacuole of
amoeba moves
excess water back out
of cell
4. Know the terms osmotic pressure, halophiles, extreme halophiles, and halotolerant.
Osmotic pressure: the pressure that would have to be applied to a pure solvent to prevent it
from passing into a given solution by osmosis
Halophiles: Salt loving organism
Extreme halophiles: Thrives in extremely high concentrations of salt
Halotolerant: Can live with salt, but does not need it to survive
5. Temp requirements for growth:
a. Know the temp range terms minimum, maximum, and optimum. How would these
appear on a growth vs temp graph?
, b. Know the characteristics for the following: psychrophiles, psychrotrophs, mesophiles,
thermophiles, and extreme-thermophiles.
Minimum temperature: lowest temperature that can support even the smallest amount of
growth.
Maximum temperature: highest temperature that can support microbial growth
Optimum Temperature: temperature where species survive/grow best. This is where the
highest growth rate occurs.
Psychrophiles ● Live in the coldest temperatures
● Reproduce at just a little above freezing
● Once at 10-15 degrees celsius they can no longer grow
● Rarely pathogenic due to location
Psychrotrophs ● Grow very well at 20-25 degrees celsius
● Room temp=25 degrees
● Skin temp=30 degrees
● Often food pathogens because of room temp
● Can multiply in fridge
● Grow poorly at internal body temp (37 degrees)
● Can cause food poisoning by secreting toxins on food
Mesophiles ● Optimal temperature=37 degrees celsius
● Grow well in internal body and on skin
● Most human pathogens are mesophiles
● Infection causes blood to rush to area → increasing heat →
increasing microbial replication
Thermophiles ● Heat-loving
● 70 degrees celsius
● Adapted to high temperatures by having heat resistant
DNA/enzymes
Extreme-Thermophiles ● Can grow at temperatures above boiling (100 degrees
celsius)
6. Oxygen: understand toxin oxygen and how cells deal with this using SOD and catalase.
Toxin Oxygen: As oxygen enters cellular reactions, it is transformed into several toxic products:
1. Singlet oxygen
2. Superoxide ion
3. Hydroxyl radicals
4. Hydrogen peroxide
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