Lecture 5 (cyanobacteria)

Question 1

Define Stromatolites

Answer 1

The fossils of large dome-like structures made of colonies of cyanobacteria that form microbial mats

Question 2

What are microbial mats?

Answer 2

Densely packed layers of microbes, mostly cyanobacteria.

Question 3

Describe the layers of microbes in microbial mats

Answer 3

Top layer consists of of oxygenic photosynthetic blue-green algae which are cyanobacteria. Middle layer consists of anoxygenic photosynthetic purple sulfur bacteria (protobacteria). Bottom layer consists of anaerobic bacteria that appear dark or black.

Question 4

What are protobacteria?

Answer 4

They are anoxygenic phototrophs. Their electron donor is H2S. They take in H2S and produce sulfur.

Question 5

Define thylakoid

Answer 5

The membrane inside chloroplasts on which pigment molecules organize themselves. This is where photosynthesis occurs and where chlorophyll a and accessory pigments are found.

Question 6

Define phycobilisomes

Answer 6

The structure that pigment molecules are organized as on the thylakoid membrane.

Question 7

What are akinetes?

Answer 7

Akinetes are specialized cyanobacteria that are thick-walled, in resting stage, and filled with food resources. They are storage units.

Question 8

What are heterocysts?

Answer 8

Heterocysts are specialized cyanobacteria that are anaerobic and receive nutrients from akinetes to fix nitrogen. They lack chlorophyll.