1 - Introduction to Microbiology

Question 1

Three domains

Answer 1

Archaea
Bacteria
Eukarya

Question 2

Bacteria info

Answer 2

1-6 micrometers long
Mostly very small, can be some that are visible to naked eye

Question 3

Archaea info

Answer 3

Can be extremophiles - can grow in extreme conditions
No known pathogenic archaea

Question 4

Fungi info

Answer 4

Eukaryotic microbes
Size varies enormously
Commonly found with spores

Question 5

Protists info

Answer 5

Very diverse - most eukaryotes are protists
Size range - 1-150 micrometers

Question 6

Different types of microorganisms

Answer 6

Bacteria
Archaea
Fungi
Protozoa

Question 7

Significance of microorganisms in global biomass

Answer 7

4-6 x 10^30 microbial cells in earth estimated
Microbial carbon equals that of all plants
Microbial Nitrogen and Phosphorous is 10x that of plant biomass

Bacteria and Archaea:
Major portion of biomass on Earth
Key reservoirs of nutrients for all life

Question 8

Five kingdoms

Answer 8

Plants
Fungi
Animal
Protists
Bacteria

Question 9

Distribution/abundance of microorganisms (not in size order)

Answer 9

Cloud water (least abundant
Seawater
Soil
Rivers and lakes
Marine subsurface
Human cells and bacteria in humans (most)

Question 10

Why so many microorganisms

Answer 10

Rapid growth rate in environment
Many changes of speciation through random mutations
Exchange of genetic material (lateral gene transfer)
Every available niche is occupied by specifically adaptations microbes
A very long evolutionary history (3.8 billion years)

Question 11

Phototroph def

Answer 11

Converts light energy to chemical, usable energy for organism

Question 12

Chemotroph def

Answer 12

Utilise energy from chemical bonds, breaking them open to convert energy

Question 13

Organotroph

Answer 13

Organic compounds as electron donors

Question 14

Lithotroph

Answer 14

Inorganic compounds as electron donors

Question 15

Autotrophs

Answer 15

CO2 as a carbon source

Question 16

Heterotrophs

Answer 16

Organic compound as a carbon source

Question 17

Photolithoautotroph - example

Answer 17

Cyanobacteria (and plants!)
- light energy used
- water as an electron donor
- CO2 fixation for ATP production

Question 18

Chemoorganoheterotroph example

Answer 18

E. Coli (and most animals)
- chemical bond energy (O2)
- organic compounds (e.g. sugars) as electron donors
- organic compounds as carbon source - eat other organic compounds

Question 19

Chemolithoautotroph - example

Answer 19

Thiobacillus spp.
- chemical bond energy
- inorganic compound (reduced sulfur compounds) as electron donor
- Fix CO2

Question 20

Nutrients required for bacterial growth in the lab

Answer 20

Primary macronutrients:
- Carbon (CO2, or organic Carbon)
- H, O, N, S, P, K, Mg, Na, Ca, Fe

Micronutrients:
- B, Cr, Co, Cu, Fe, Mn, Mo, Ni, Se, W, V, Zn

Question 21

Phototroph growth in the lab

Answer 21

Synthesise all their own cellular components (including all amino acids, nucleotides, vitamins)

Question 22

Fastidious bacteria growth in the lab

Answer 22

Need organic components, such as vitamins, in growth medium

Question 23

Luria broth - complex medium broth makeup

Answer 23

Glucose - 15g
Peptone - 5g
Yeast extract - 5g
KH2PO4 - 2g

• dissolved in distilled water - pH 7
  Peptone (hydrolysed protein) and yeast extract are “undefined” chemicals containing cellular material

-most bacteria will grow using this complex growth medium

Question 24

Defined medium - Thiobacillus thioparus

Question 25

More complex media - where some microbes need to be grown

Answer 25

- some microbes have to be grown inside eukaryotic cells or in animals, or in other specific environments E.g. syphilis grown in testicular cells, leprosy agent grown on feet of mice or armadillos

Question 26

Growth of bacteria

Answer 26

- Asexual reproduction by binary fission or budding - Cells double in’s size then split in two - exponential growth - 2, 4, 8 etc. - incomplete separation produces pairs or larger assemblies of bacteria

Question 27

Why bacterial growth is limited

Answer 27

Exponential growth of bacteria can produce large numbers All environments are limited though - so limit is carrying capacity of medium - limited by space and availability of nutrients - most bacteria subject to bacterial growth curve

Question 28

Bacterial growth curve stages

Answer 28

Lag phase - adapt to new conditions Log/exponential phase - exponential growth Stationary phase - limited by nutrients, buildup of toxic waste products - inhibit growth Death phase - organisms start dying off, and may lyse

Question 29

Measurements of growth

Answer 29

Cell number Optical density Fresh/dry weight (biomass?) Protein DNA

Question 30

Instruments to measure growth of microbes

Answer 30

Haemocytometer Dilution plating (serial dilutions etc.) Turbidmetry

Question 31

typical prokaryotic cell organelles

Answer 31

Cell wall Cytoplasmic membrane (plasma membrane) Nucleoid - cytoplasm Plasmid Ribosomes

Question 32

typical eukaryotic cell organelles

Answer 32

cell wall cytoplasmic membrane mitochondrion nuclear membrane nucleus ribosomes ER - endoplasmic reticulum (rough and smooth) cytoplasm golgi complex