Cyanobacteria I

Question 1

Are cyanobacteria prokaryotic or eukaryotic

Answer 1

They are all prokaryotic - they have no membrane bound organelles

Question 2

Do cyanobacteria exhibit sexual reproduction

Answer 2

No

Question 3

What is the biological species concept

Answer 3

This is based upon sexual exclusivity where the same species can sexually reproduce with each other

Question 4

Does the biological species concept apply to cyanobacteria

Answer 4

No because the biological species concept is based on the evidence of sexual reproduction whereas cyanobacteria are asexual (they do viral transference/transduction of genetic material)

Question 5

Which species concepts apply to cyanobacteria

Answer 5

The phylogenetic species concept and the morphological species concept

Question 6

Describe the phylogenetic species concept

Answer 6

Molecular and morphological evidence is used to define several species (here cyanobacteria that share one or more distinct traits denote a species and tentatively their relatedness to other species)

Question 7

Describe the morphological species concept

Answer 7

species are defined by a set of distinct physical features that are considered to be reliable or conservative

Question 8

Describe the types of morphologies we have seen for cyanobacteria

Answer 8

• colonial morphology
• filamentous morphology

Question 9

What is the key taxonomically diagnostic feature of the cyanobacteria

Answer 9

Cyanobacteria are distinguished from all other algae by their prokaryotic cell condition (they are the only prokaryotes amongst the algae) –> so they don’t have a nucleus, chloroplast (but have chlorophyl), and no membrane bound organelles

Question 10

Do cyanobacteria have a cell wall

Answer 10

no - they are prokaryotic and have no true cell wall

Question 11

What is a cyanophycin granule

Answer 11

• in cyanobacteria
• this is pellets of stored nitrogen (is useful if they have extra nitrogen than they need)

Question 12

What is a polyphosphate body

Answer 12

• in cyanobacteria
• with this cyanobacteria can store phosphorous
• makes cyanobacteria good at competing for phosphorous
• they can take it up in excessive amounts (luxury consumption) which then turns into a polyphosphate body

Question 12

What is a sheath

Answer 12

slimy layer, cyanobacteria tend to be sticky because of this sheath

Question 12

What are phycobilisomes

Answer 12

• in cyanobacteria
• these are pigments that help harvest light for photosynthesis (but this is not chlorophyl)

Question 12

What types of branching can cyanobacteria show

Answer 12

true branching and false branching

Question 12

describe aerotopes

Answer 12

• in cyanobacteria
• these are stacks of air chambers, are crystals that expand and contract with air depending on how buoyant the cell wants to be in the water column

Question 12

Instead of starch, what do cyanobacteria produce

Answer 12

glycogen, they store this instead of starch

Question 13

Why is the finer identification of cyanobacteria to the species level problematic

Answer 13

because of potential polymorphism - depending on what environmental conditions a genus is growing in it may be polymorphic

Question 14

What is the most practical used concept to describe the cyanobacteria

Answer 14

the morphological species concept

Question 15

What is the caveat to the morphological species concept when talking about cyanobacteria

Answer 15

Polymorphism - morphological traits must be reliable and consistently observable, but polymorphism can occur due to genotypic differentiation or phenotypic plasticity (so not all traits are conservative, species can look different based on the environment they are collected from)

Question 16

What is a particular example of polymorphism in cyanobacteria

Answer 16

They can produce an extracellular sheath as a function of environmental stress

Question 17

Describe the 5 main structures seen inside cyanobacterial cells

Answer 17

1. Cyanophycin granule (for nitrogen storage)
2. sheath
3. phycobilisomes (these line the thylakoid membranes and help with resonance transfer)
4. aerotopes
5. polyphosphate body (help with phosphorous storage)

Question 18

Describe the two structures on the outside that cyanobacteria may produce

Answer 18

1. heterocyte (enables nitrogen fixation)
2. akinete

Question 19

What is the more powerful species concept for cyanobacteria

Answer 19

the phylogenetic species concept