Prokaytoic Algae Flashcards
Domain of prokaryotes
Eubacteria
Phylum Cyanobacteria contains ____, _____ or ______ forms
Unicellular, filamentous, colonial
Where does photosynthesis take place in Cyanobacteria
Photosynthetic apparatus is not bound to chloroplasts, but rather on the surface of thylakoid membranes.
Do Cyanobacteria have nucleus?
No definite nucleus, although the single chromosome is generally confined to a central area.
Cell wall of Cyanobacteria is usually enclosed in a ____
Mucilage sheath
Order Chroococcales
Artificial group of single-celled or colonial Cyanobacteria that reproduce solely by fission. Cell shape ranges from spherical to oval or cylindrical.
Most genera form regular or irregular aggregates of cells that are imbedded in mucilage. The order is subdivided based on planes or division of cells
Family Microcystaceae and Merismopediaceae above groups
Phylum Cyanobacteria
Order Chroococcales
Gloeocapsa sp. division
Family Microcystaceae
The cells fail to separate on division, resulting in a small colony. Each cell within the colony secretes one or more mucilage layers, resulting in a layered sheath.
Merismopedia sp. division
Family Merismopediaceae
This genus has 2 cells that form 2-dimensional colonies as a result of cell division in two planes
Microcystis sp. arrangement
Family Microcystaceae
One of the common genera of colonial Cyanobacteria in Manitoba, these organisms grow as spherical or irregular colonies of small, densely packed with black gas vesicles
Order Oscullatoriales
Filamentous Cyanobacteria without specialized cells
Oscillatoria sp.
Family Oscullatoriaeae
Solitary filaments in which there is often a slight tapering in each filament. Mucilage sheaths are very thin and cells are wider than long.
Oscillatoria reproduction
Reproduction is by fragmentation which occurs in a region of dead cells (necridia) to give filament fragments called “hormogonia pl, or homogone)
Fragmentation is followed by cell division to return the filament to near original length
Lyngbya sp. design
Order Oscillatoriales
Family Oscillatoriaceae
Similar to Oscillatoria so, but have definite sheaths that extend beyond the cells of the filaments
Order Nostocales design
-multicellular, filamentous Cyanobacteria with different cell types (vegetative cells, heterocysts, akinetes)
-filaments show isopolar growth (from both ends) and the cells are spherical, barrel-shaped or cylindrical.
-filaments unbranched and constant diameter (not tapered)
-contain heterocysts, that fixate nitrogen.
Akinetes
Thick-walled resting spores that survive unfavourable conditions such as droughts for up to 70 years
Concentrated carbs!!!
Larger than vegetative cells and granulated (glycogen and cyanophycin)
Nostoc sp. appearance
Order Nostocales
Family Nostocaceae
Globular, bead-like cells arranged in tangled filaments. Filaments are usually embedded in a mucilage matrix that is bound by a leathery membrane. Heterocysts, mucopolysaccharide sheath
Colony size varies from microscopic to 10cm across
Anabaena sp. appearance
Order Nostocales
Family Nostocaceae
Filaments are solitary or in a soft matrix. Cells are spherical to sub-cylindrical. Heterocysts and akinetes are usually evident.
Heterocysts are the size of ______ but without _____
Vegetative cells
Granules
Gloeotrichia sp. appearance
Order Nostocales
Family Nostocaceae
Often planktonic. Each basal heterocyst is usually adjacent to a cylindrical akinete
Rivularia sp. Appearance
Family Rivulariaceae
Filaments taper from the base to the apex (Herero polar growth). Epiphytic (attach to substrate) Filaments arranged in radiating colonies. Basal heterocysts. No Akinetes
Form hemispherical colonies
Basal heterocysts, no akinete
Filaments may be solitary or in colonies
Scytonema sp. appearance
Family Scytonemataceae
Filaments with wide sheaths. The mucilage sheath is thick and lamellate. Pseudo-branching at a heterocyst or at the necridium
Filaments are Isopolar
Family Stigonemataceae
Only group of cycanophytes which exhibit true branching (division of a cell in a second plane to initiate a branch). Filaments may by uniseriate (one cell wide) or multiseriate (more than one cell wide)
Stigonema sp. and Fischerella sp.
Family Stigonemataceae
Belong to the only group of Cyanobacteria that branch
Hormogonia
Fragmented new trichomes caused by the breakage of a filament by necridia
Necridia
Dead cells
In Scytonema sp. free ends of filaments _____ the sheath
Rupture
Isopolar growth
Untapered
Growing same width of cells from both ends
Heteropolar
Growth into two sizes of widths on either end of filament
Purpose of mucilage sheath
Prevent desiccation
Attach to other cells
Acts as filter for UV= sunscreen
Microcystis sp. and livestock issue
Produce toxins like Microcystin and Anatoxin that are harmful to livestock. Accumulation in animals water source causes dugout death
What is meant by filamentous
Chain of cells
What is meant by unspecialized cells
Only vegetative
No heterocysts or akinetes
Heterocyst function
Fix nitrogen
Why do heterocysts have a thick outer wall?
Prevent oxygen from getting into cell and disrupting nitrogenase
How does pseudo branching occur and in what species of Cyanobacteria does it happen?
Cells adjacent to necridia push up against abs grow outward. Not real branching as they still are only dividing in one plane.
Scytonema sp.
Uniseriate vs multiseriate
One cell row
Multiple cell rows
