MC5-6: Bacterial metabolism and phototrophy Flashcards Preview

BS1040: Microbiology and Cell Biology > MC5-6: Bacterial metabolism and phototrophy > Flashcards

Flashcards in MC5-6: Bacterial metabolism and phototrophy Deck (57)
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1

When did bacteria evolve?

Approx. 3.5 billion years ago

2

How many species of animals, plants, and bacteria are there on Earth?

Animals: 10–30 x106

Plants: (estimated) 300,000

Bacteria: (estimated) 107 – 109

3

How many cells are there on Earth at any one time?

4–6 x1030 cells

4

Where are the majority of bacteria and archaea found?

Open ocean: 1.2 x1029

Soil: 2.6 x1029

Oceanic sediment: 3.5 x1030

Terrestrial sediment: 0.25–2.5 x1030

Human guts: approx. 3.9 x1023

5

Define 'metabolism'

The set of chemical reactions that occur in living organisms in order to mainain life. Metabolic processes allow organisms to grow, reproduce, maintain structures, and respond to their environments

6

Define 'catabolism'

Breaking down organic matter, e.g. to harvest energy in cellular respiration

7

Define 'anabolism'

The use of energy to contruct components of cells such as proteins and nucleic acids

8

What are the three basic requirements for life?

  1. Energy source
  2. Carbon source
  3. Electron source

9

What are the two different possibilities for obtaining energy, and what are the processes that lead to energy obtention?

  • Phototrophy – 'eating' light energy
    • Photosynthesis – converting CO2 to sugars using sunlight energy
  • Chemotrophy – 'eating' chemical bond energy
    • Respiration – transforming energy from nutrients into chemical energy with O2 usually as the terminal electron acceptor
    • Fermentation – process of energy production in cell under anaerobic conditions

10

What is the so-called 'energy currency' of bacteria, and what are the two methods by which this is generated?

ATP

Substrate-level phosphorylation and oxidative phosphorylation

11

What are the carbon sources of:

  1. autotrophs
  2. hterotrophs?

  1. Autotrophs = CO2
  2. Heterotrophs = organic compounds

12

Where do:

  1. photoautotrophs
  2. photoheterotrophs
  3. chemoheterotrophs
  4. chemoautotrophs

get their energy and carbon from?

  1. Photoautotroph
    Energy = light
    Carbon = CO2
  2. Photoheterotroph
    Energy = light
    Carbon = organic compounds
  3. Chemoheterotroph
    Usually, a single organic compound acts as a source for both energy and carbon
  4. Chemoautotroph
    Energy = oxidation of inorganic chemical compounds
    Carbon = CO2

13

What are the four nutritional categories of life?

  • Photoautotroph
  • Photoheterotroph
  • Chemoautotroph
  • Chemoheterotroph

14

Why can O2 be very harmful to organisms without protective mechanisms?

It is a harsh oxidising agent

 

15

What is the name for organisms that can grow in oxygen?

Aerobes

16

How do aerobes utilise oxygen?

They use aerobic respiration as their principle energy generation by using O2 as their terminal electron acceptor

17

Why can anaerobes not live in oxygenated environments?

They never developed protective mechanisms against oxygen

18

Give two examples of environments in which anaerobes live.

  • Animal intestinal tract
  • Lake/ocean sediments

19

What is different about anoxygenic photosynthesis?

  • Carried out in oxygen-free environments
  • Electron donor is water
  • No oxygen is produced

20

What are the types of aerobic and anaerobic metabolism?

Aerobic

  • Aerobic respiration
  • Oxygenic photosynthesis
  • Anoxygenic photosynthesis

Anaerobic

  • Fermentation
  • Anaerobic respiration
  • Anoxygenic photosynthesis

21

How is ATP generated in bacteria?

Phototrophy

  • Pigments absorb energy from the sun
  • An electron with a higher energy level is then released from within the pigment
  • This electron is passed through an electron transport chain, with the generation of energy by formation of ATP

22

What is the carbon source of:

  1. autotrophs
  2. heterotrophs
  3. mixotrophs?

  1. Autotrophs: CO2
  2. Heterotrophs: organic compounds
  3. Mixotrophs: both

23

What are the two types of phototrophy and how do they differ?

  • Anyoxygenic
    • Used bacteriochlorophyll
    • Has 1 reaction centre
  • Oxygenic
    • Uses chlorophyll
    • Has 2 reaction centres

24

What are the five major groups of prokaryotes that use anoxygenic photosynthesis, and which group used oxygenic photosynthesis?

Anoxygenic

  • Purple sulphur bacteriochlorophyll b
  • Purple non-sulphur bChl a b
  • Green non-sulphur bChl a b
  • Green sulphur bChl c d e f
  • Heliobacteria bChl g

Oxygenic

  • Cyanobacteria chla

25

What do purple sulphur bacteria use as an electron donor? Give examples of the bacteria.

  • H2S
  • Thiopedia roseopersicinia
  • Ameobacter purpureus

26

What do purple non-sulphur bacteria use as an electron donor? Give examples of typical genera.

  • Hydrogen
  • Rhodospirillum
  • Rhodopseudomonas
  • Rhodobacter

27

What do green sulphur bacteria use as electron donors? Give examples of species.

  • H2S / S / S2O32– (which invariably becomes H2SO4)
  • Chlorobium species

28

What do green non-sulphur bacteria use as electron donors? Give an example of a species.

  • Hydrogen
  • Chloroflexus

29

What do heliobacter use as an electron donor?

H2S

30

What are the only oxygenic phototrophic prokaryotes?

Cyanobacteria