MICRO 401 TEST 2 QUESTIONS AND VERIFIED
ANSWERS
1) What are the special considerations for survival at the high temperatures that
thermophiles such as Aquificae and Thermotogae thrive in - Answers - - Proteins
- High ionic DNA concentration (prevents denaturation) - super coiled
- Structural and sequencing changes in RNA
- Have enzymes that desire high temperatures
- Cell membrane has increased temperature and fluidity
- Synthesize ATP and GTP when necessary to avoid denaturation
2) Explain the mechanism through which Deinococcus is thought to be able to survive
very high levels of radition - Answers - - Quickly repair chromosomes (12-24 hours)
- Proteins highly resistant to stress, possibly from manganese
- Protected from oxygen radicals
3) Define oxygenic and anoxygenic photosynthesis - Answers - - Oxygenic - oxidizes
water to get oxygen
- Anoxygenic - does not produce oxygen
1. How do different photosynthetic pigments contribute to the ecology of photosynthetic
microbes - Answers - - Photosynthetic pigments are used to collect light
2. What are chlorosomes, How do they function within photosynthetic organisms such
as Chlorobi and Chloroflexi - Answers - - Photosynthetic antenna in green sulfur
bacteria
- Contains up to 250,000 chlorophyll structures to help capture light in places light can
be rare
3. What is the purpose of heterocysts; How do they form; What special modifications do
they contain in order to protect the nitrogenase enzymes from oxygen; How do
heterocysts interact with the cells next to them - Answers - - Heterocysts - can fix
nitrogen into amino acids
- Form when there little nitrogen available
- Cannot revert and reproduce
- Turn off photosystem II and stop the cell from O2 production
- Photosystem I can still make ATP
- Thick cell walls to keep oxygen out
- Heterocysts pass amino acids to vegetative cells, in return get nutrients needed for the
process
4. What problematic process can occur after a cyanobacterial bloom - Answers - -
Polluted body of water (fertilizers) leads to large bloom of cyanobacteria. Nutrients
, quickly runs out and all of the cyanobacteria die. Lots of organic molecules are released
and chemoheterotrophs have a large bloom. The consume large amounts of O2 which
can cause the death of larger organisms like fish and frogs.
5. Planctomycetes are somewhat unique in that they have internal membrane-defined
compartments. What is the difference between the location and contents of the
riboplasm and the paryphoplasm in these cells; Why is it advantageous for the annamox
reaction to be carried out in specialized compartments - Answers - - Riboplasm - inside
the endoplasmic membrane - has ribosomes and contains genetic material
- Paryphoplasm - In between the cell membrane and inside cytoplasm - contains no
ribosomes
- Annamox is the oxidation of ammonia, and benefits from specialized compartments to
protect the cell since the intermediates are extremely toxic
6. Describe the biphasic life cycle of Chlamydiae - Answers - - Reticulate bodies -
larger, metabolically active, and can grow and divide
i. Found only in host cell
ii. Grow and divide until nutrients runs out, then they become Elementary bodies and
the host cell lyses
- Elementary bodies - sole purpose for disease transmission
i. Smaller and not metabolically active
ii. Attach to host cell and taken up by endocytosis
iii. In the vesicle of the host cell they become reticulate bodies
7. What types of modifications have Chlamydiae undergone as obligate intracellular
parasites (Think of genome size, things the organisms might need to obtain from the
host, etc) - Answers - - Undergo genome reduction (energy parasites)
- Gain NAD+ and ATP
8. Explain how Spirochaetes move - Answers - - Can have 2-200 flagella
- Two polar flagella that come from the ends but wrap around the whole cell in both
directions (together known as the axial filament)
- Inside of the cell moves one direction while the outside moves another
- Produce a corkscrew movement
9. What are two proposed mechanisms for how bacteria, including Bacteroidetes,
gliding - Answers - - Can only glide when in contact with a surface
- Proposal 1 - produce polysaccharides (slime) for gliding movement
- Proposal 2 - motors move with adhesions on the outer part of the cell
10. What are the advantages to gliding - Answers - - Find nutrients
- Can move on dryer surfaces (like the colon)
- Have enzymes that can bring carbohydrates into the cell
11. What is meant by the term "oligotrophic" - Answers - - Oligotrophic - can grow in
areas with low amounts of nutrients
ANSWERS
1) What are the special considerations for survival at the high temperatures that
thermophiles such as Aquificae and Thermotogae thrive in - Answers - - Proteins
- High ionic DNA concentration (prevents denaturation) - super coiled
- Structural and sequencing changes in RNA
- Have enzymes that desire high temperatures
- Cell membrane has increased temperature and fluidity
- Synthesize ATP and GTP when necessary to avoid denaturation
2) Explain the mechanism through which Deinococcus is thought to be able to survive
very high levels of radition - Answers - - Quickly repair chromosomes (12-24 hours)
- Proteins highly resistant to stress, possibly from manganese
- Protected from oxygen radicals
3) Define oxygenic and anoxygenic photosynthesis - Answers - - Oxygenic - oxidizes
water to get oxygen
- Anoxygenic - does not produce oxygen
1. How do different photosynthetic pigments contribute to the ecology of photosynthetic
microbes - Answers - - Photosynthetic pigments are used to collect light
2. What are chlorosomes, How do they function within photosynthetic organisms such
as Chlorobi and Chloroflexi - Answers - - Photosynthetic antenna in green sulfur
bacteria
- Contains up to 250,000 chlorophyll structures to help capture light in places light can
be rare
3. What is the purpose of heterocysts; How do they form; What special modifications do
they contain in order to protect the nitrogenase enzymes from oxygen; How do
heterocysts interact with the cells next to them - Answers - - Heterocysts - can fix
nitrogen into amino acids
- Form when there little nitrogen available
- Cannot revert and reproduce
- Turn off photosystem II and stop the cell from O2 production
- Photosystem I can still make ATP
- Thick cell walls to keep oxygen out
- Heterocysts pass amino acids to vegetative cells, in return get nutrients needed for the
process
4. What problematic process can occur after a cyanobacterial bloom - Answers - -
Polluted body of water (fertilizers) leads to large bloom of cyanobacteria. Nutrients
, quickly runs out and all of the cyanobacteria die. Lots of organic molecules are released
and chemoheterotrophs have a large bloom. The consume large amounts of O2 which
can cause the death of larger organisms like fish and frogs.
5. Planctomycetes are somewhat unique in that they have internal membrane-defined
compartments. What is the difference between the location and contents of the
riboplasm and the paryphoplasm in these cells; Why is it advantageous for the annamox
reaction to be carried out in specialized compartments - Answers - - Riboplasm - inside
the endoplasmic membrane - has ribosomes and contains genetic material
- Paryphoplasm - In between the cell membrane and inside cytoplasm - contains no
ribosomes
- Annamox is the oxidation of ammonia, and benefits from specialized compartments to
protect the cell since the intermediates are extremely toxic
6. Describe the biphasic life cycle of Chlamydiae - Answers - - Reticulate bodies -
larger, metabolically active, and can grow and divide
i. Found only in host cell
ii. Grow and divide until nutrients runs out, then they become Elementary bodies and
the host cell lyses
- Elementary bodies - sole purpose for disease transmission
i. Smaller and not metabolically active
ii. Attach to host cell and taken up by endocytosis
iii. In the vesicle of the host cell they become reticulate bodies
7. What types of modifications have Chlamydiae undergone as obligate intracellular
parasites (Think of genome size, things the organisms might need to obtain from the
host, etc) - Answers - - Undergo genome reduction (energy parasites)
- Gain NAD+ and ATP
8. Explain how Spirochaetes move - Answers - - Can have 2-200 flagella
- Two polar flagella that come from the ends but wrap around the whole cell in both
directions (together known as the axial filament)
- Inside of the cell moves one direction while the outside moves another
- Produce a corkscrew movement
9. What are two proposed mechanisms for how bacteria, including Bacteroidetes,
gliding - Answers - - Can only glide when in contact with a surface
- Proposal 1 - produce polysaccharides (slime) for gliding movement
- Proposal 2 - motors move with adhesions on the outer part of the cell
10. What are the advantages to gliding - Answers - - Find nutrients
- Can move on dryer surfaces (like the colon)
- Have enzymes that can bring carbohydrates into the cell
11. What is meant by the term "oligotrophic" - Answers - - Oligotrophic - can grow in
areas with low amounts of nutrients
