Bacteria and Archaea

Question 1

What do microbes include?

Answer 1

Archaea, bacteria and eukaryotes

They are a range of cell sizes

Question 2

Who initially discovered bacteria?

Answer 2

Leeuwenhoek - he created some early sketches of what he had been seeing

This contrasted the spontaneous generation theory

Question 3

What are the key differences between archaea and bacteria?

Answer 3

• Bacteria has ether linkages
• Archaea has ester linkages
• Almost no introns in bacteria - many introns in archaea

Question 4

What sort of linkages are found in bacteria?

Answer 4

Ether

Question 5

What sort of linkages are found in archaea?

Answer 5

Ester

Question 6

What are introns and exons?

Answer 6

Introns = non-coding DNA

Exons = coding DNA

Question 7

When was the domain archaea established?

Answer 7

In the 1970s - found to be closer to humans than bacteria

Achaea generally found in extreme conditions –> huge genetic diversity

Question 8

What is the ratio of bacterial cells in the colon?

Answer 8

They outnumber human cells around 10:1

Question 9

Give 4 examples of how important bacteria are:

Answer 9

• Responsible for many of earth’s processes e.g. photosynthesis & digestion
• No mammal can digest cellulose –> bacteria helps this
• Dealing w waste in sewage farms
• Also cause sepsis & food decay

Question 10

What are the 4 nutritional & metabolic pathways that bacteria use?

Answer 10

• Phototrophs
• Chemotrophs
• Autotrophs
• Heterotrophs

Question 11

How do phototrophs survive?

Answer 11

They use light as a source of energy

Question 12

How do chemotrophs survive?

Answer 12

They use chemical sources of energy

Question 13

How do autotrophs survive?

Answer 13

Only require CO2 as a source of carbon

Question 14

How to heterotrophs survive?

Answer 14

One or more organic molecules (e.g. glucose as a source of energy

Question 15

What are the types of bacteria that we’re familiar with?

Answer 15

• Alpha proteobacteria
• Beta proteobacteria
• Gamma proteobacteria
• Delta proteobacteria
• Epsilon proteobacteria
• Chlamidias
• Spirochetes
• Cyanobacteria
• Gram-positive bacteria

Question 16

Give an example of an alpha proteobacteria

Answer 16

Rhizobium species live within nodes of roots of leguminous plants

Some species (e.g. Agrobacterium) can produce tutors in plants - used to genetically engineer the plants

Question 17

What are alpha proteobacteria usually like?

Answer 17

Many species are closely associated w eukaryotic hosts (e.g. Rhizobium species)

• Convert atmospheric N2 compounds the host plant can use

Origin of mitochondria?

Question 18

What are beta proteobacteria?

Answer 18

• Nutritionally diverse subgroup incl nitrosomonas species
• A wide range of aquatic species
• Some pathogens

Question 19

What do Nitrosomonas species do?

Answer 19

Play important role in nitrogen recycling by oxidising ammonium (NH4+) to nitrite (NO2-)

A type of beta proteobacteria

Question 20

What are gamma proteobacteria?

Answer 20

• Auxotrophs including Sulphur bacteria (e.g. Thiomargarita namibiensis) obtain energy by oxidising H2S to sulphur

Some heterotrophic pathogens

Question 21

Name some of the heterotrophic pathogens under gamma proteobacteria

Answer 21

• Legionella
• Salmonella
• Vibrio
• E.coli

Question 22

What is delta proteobacteria?

Answer 22

Includes myxobacteria –> congregate into fruiting bodies & release resistant myxospores

Bdelovibrios - small, highly motile bacteria, prey on other bac by invading periplasm & eat them from within

Question 23

What is epsilon proteobacteria

Answer 23

Incl human pathogens & some non-pathogens (Wollinella species)

Question 24

Give some examples of the human pathogens used epsilon proteobacteria:

Answer 24

• Campylobacter spices = a major cause of food-born intestinal illness
• Helicobacter pylori = most widely distributed human pathogen causing gastritis, duodenal and gastric ulcers, gastric cancer

Question 25

What are the chlamydias?

Answer 25

Obligate intracellular pathogen

Includes human pathogens