Microbial World

Question 1

Three main virus morphologies

Answer 1

Helical
Icosahedral
Binal

Question 2

Helical

Answer 2

Spiral shape with capsid proteins curving cylindrical along an axis and only one kind of protein

Question 3

Marine Viruses characteristics

Answer 3

• no inherent metabolism
• need other cells to reproduce
• classified as obligate intracellular parasites

Question 4

Lytic

Answer 4

Attach to living cells, inject nucleic acid into cell which commands the cell to replicate the virus, cell then “bursts” through lysis releasing viral cells that can then infect new cells or host (rapid spread)

Question 5

Lysogenic

Answer 5

Reproduce by causing their nucleic acid chain to become part of the host cell’s genome, which are then transmitted to daughter cells (slower spread)

Question 6

Marine viruses: biodiversity and distribution

Answer 6

-Estimated 10^30 viruses in the ocean
-water samples often contain 100-10,000 viral genotypes
- most diverse and abundant component of plankton community
-smaller size = greater abundance per unit area
-highly abundant at deep-sea floor

Question 7

Bacteriophages

Answer 7

Highly diverse group of viruses that target and destroy bacteria

Question 8

What is DOM

Answer 8

Dissolved organic matter

Question 9

Why is DOM important

Answer 9

Major food source for marine microbes, mixture derived from decomposition products of plant material, bacteria and algae

Question 10

Viral shunt

Answer 10

Mechanism that prevents marine microbial particulate organisms matter (POM) from migrating up trophic levels
-returns energy to DOM pool

Question 11

Cyanobacteria

Answer 11

Photosynthetic prokaryotes, oxygen as byproducts

Photosynthetic pigments: chlorophyll a (sometimes b), phycocyanin (blueish), phycoerythrin (absorbs blue light )

Question 12

Harmful algae bloom (HAB)

Answer 12

Explosive growth of algae or Cyanobacteria, once they die and sink to the bottom the are decomposed by bacteria. Decomposition sucks away oxygen and create dead zones absent of oxygenated water

Question 13

Purple and Green bacteria

Answer 13

Anaerobic photosynthetic bacteria, growth inhibited by high oxygen concentration
Produce sulfates (mangrove mud flats smell)

Question 14

Chemosynthetic bacteria

Answer 14

Aerobic process
Energy source: hydrogen sulphide, ammonium, nitrite and reduced iron
Occurs in hydrothermal vents, cold seeps and mudflats

Question 15

Aerobic respiration

Answer 15

Oxygen used to make energy from carbohydrates
-If oxygen is present it will always be favored over anaerobic respiration because it’s more efficient

Question 16

Anaerobic respiration

Answer 16

Oxygen not used and produced less energy but more quickly
Some products of anaerobic reproduction can be toxic to plant and animal (H2S produced during sulphate reduction)

Question 17

Archaea characteristics

Answer 17

-reproduce asexually (budding, fragmentation, binary fission)
-ether-linked lipids in cell wall
-can use broad range of energy sources
-many are extremophiles
-most are commensal or mutualistic ( archaea in termite to digest cellulose material)

Question 18

Protists characteristics

Answer 18

-mostly unicellular, aquatic, photosynthetic
- contain nucleus and other organelles enclosed by membrane

Question 19

Diatoms characteristics

Answer 19

-unicellular and photosynthetic
-cell wall (frustule) made of silica
-coloration from yellow & brown pigments and chlorophyll a & c

Question 20

Dinoflagellates

Answer 20

-planktonic unicellular organisms
-two flagella that direct movement
-cellulose-armored cell walls which have spines, pores
-photosynthesize and ingest food (mixotrophy