Exam I.1 Cyanobacteria
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General Facts of Cyanobacteria
1) what color can they be? What color are they mostly?
2) what kind of organism are they?
3) What can they perform?
4) What were they previously classified as?
5) what are they all?
- 1) red/ blue-green
- 2) prokaryotes
- 3) nitrogen- fixation and photosynthesis [doesn't use water and oxygen isn't the end product]
- 4) algae
- 5) all aquatic and a type of bacteria
Similarities with Bacteria
- 1) the way they divide (binary fission)
- 2) cell wall is the same in bacteria (contains peptidoglycan); this cell wall will only be seen in bacteria
- 3) contain same kind of ribosomes that bacteria have
Reasons Why They Were Reluctant Not to Call them Algae
1) contains chlorophyll a (present in all true algae and plants; bacteria don't have chlorophyll a, except one)
2) have specialized cells, like algae
There are about __ species. Why was the number decreased from about 7500 to the number now?
How do they classify and why?
200; because, if you grow them in different environments, they look different. But, they can be the same organism
they classify by appearance because they can't classify by sexual reproduction (as they do with euk. species) since cyanobacteria divide by binary fission
The oldest known fossil is __. Layers of __ and __ form __. Fossil forms of ancestral cyanobacteria resemble __.
Why are they important in the atmosphere?
- 3.5 billion years
- living cyanobacteria
Important because they were the first who added oxygen to the atompshere; they shifted the composition of earth's atmosphere
1) What do they lack?
- 1) they lack a nucleus( they have naked DNA= no proteins, may be circular like in other bacteria)
- 2) ribosomes (different sizes depends on the type of cell and where they are)
- 2a) characterized by S value (gives idea of the sedimentation rate)
Explain the Svedburg value?
- MW and shape affect it
- - in the case of a typical cytoplasmic eukaryotic ribosome, it is 80S
- Prokaryotes= 70S
Cyanobacterial cells are capable of __.
Explain the membranes.
- internal membranes (not present in other bacterial cells)
- - flattened sacs like a chloroplast called thylakoids (supports the notion that these were the ancestors of eukaryotes)
Major photosynthetic pigment in the membranes
Eukaryotes contain __ and __.
- chlorophyll A (cyanobacteria only have chlorophyll A)
- - this is present in only cyanobacteria (and one bacteria) and algae adn plants
chlorophyll A and a second one
- not water- soluble
- -without chlorophyll, there is no photosynthesis
- carotenoids: xanthophylls and carotenes
- phycobilins: phycocyanin and phycoerythrin
1) explain carotenes?
2) explain xanthophylls?
- 1) most abundant is beta-carotene in plants; function is to absorb light energy and pass it to chlorophyll A (not water-soluble) orange
- 2) yellow not water soluble
1) characteristics with water?
2) n cyanobacterial cells, they usually associate with __.
3) Same or different colors?
- 1) water soluble
- 2) protein molecules
- 3) different colors
What is located on the thylakoid membrane? What are these structures called?
__ is associated with one type of protein.
- phycobilosomes (have both phycoerythrin and phycocyanin
- - each has protein molecules
Describe the pathway of light energy in phycobilosomes?
- Phycocyanin can pass light directly to chlorophyll a
- Light--> phycocyanin--> chlorophyll A
- Phycoerythrin cannot
- Light--> Phycoerythrin--> phycocyanin--> allophycocyanin--> chlorophyll A
What happens if no p-cyanin is present?
light cannot be transferred
-depends on __
- what is the blue green pigment from
-what are chloroplasts?
- the proportion of different pigments
- chlorophyll and phycocyanin
- phycoerythrin is prominent (the red sea is due to this, but not red tide)
descendents of cyanobacteria
Cytoplasm of cyanobacteria looks __. What is in it and what does it act like?
- This is not much different from ___. It acts as a __ in the cytoplasm and may have __.
It can also store molecules in the form of __.
- cyanophycean starch (storage carb in the cytoplasm)
- nitrogen storing molecule
- aspartic acid
What else might they have in their cells? For what purpose?
- gas vacuoles
- floating [buoyancy], shielding/ protection of photosynthetic pigments/ shielding from visible light/ UV light
Why should cyanobacteria float?
What can gas vacuoles do?
up toward the surface (but not at the surface) of water to give them light
disappear under pressure
What kind of surrounding do gas vacuoles have?
a crystalline sheath; not surrounded by a membrane; it is pure protein
What is special about one type of cyanobacteria and which is it?
How is this different from typical bacteria?
In general, what are cyanobacteria in relation to bacterial cells?
oscillatoria princeps: it's diameter is about 60mm
typical diameter of bacteria is .5-1 mm
In general, cyanobacteria are larger than typical bacterial cells
Typical structure of a bacterial cell wall--__
What are the two major monomers in the carbohydrate (which is __) that makes up the cell wall?
The cell wall looks like __.
different from the cell wall of algae, plants, etc.
(peptidoglycan) n-acetylmuramic acid (NAM) and n-acetylglucosamine (NAG)
one big cellulose molecule
Most cyanobacteria have at least a __. This enables the ability to __.
Outside of the cell wall is __.
- Is it thick or thin?
- How does it feel?
- Made of what? Color?
- a gelatinous matrix/ sheath
- cling to things (can cause the cells to group together and also may screen out harmful radiation)
- gelatinous materia (sheath/ matrix)
- thin (you can't see it)
- causes slimy feeling
- carbs, water
- colorless, but may have pigments
protection from predators and hydration
What is not present in the cyanobacterial cell wall?
Explain the backbone of the polysaccharide.
the backbones of alternating NAM and NAG are crosslinked by five glycine molecules which attach to short peptide chains of amino acids linked to the NAM molecules
An amino acid in the __ forms __, one with _ and one with __.
These bonds are formed in an unusual way-- how?
__ blocks this transfer. Because its structure mimics that of a __, it is able to bind the __ of the specific enzyme involved and thus __ it. Without __, the cell wall cannot hold the cell together. Thus, __ acts specifically o growing bacterial cells and not on the cells of an animal host.
- peptide chain (lysine)
- three peptide bonds
- terminal glycine molecule
- each of the amino acids above and below it
by the transfer of a peptide bond from one molecule to another
- active site
Chlorophyll is a large molecule with a central core of __ held in a __. Attached to the ring is a long, __, which serves to __. __ occurs via the __ ring.
- porphyrin ring
- insoluble phytol chain
- anchor the molecule in the internal membranes of the chloroplasts or cyanobacteria cells
- Found in all __ that evolve __. It is usually the major pigment component by weight in higher plants.
- found in __, __, and higher plants.
- photosynthetic organisms
- green algae
- absence of a __.
- similar in structure to __.
__- red, orange, or yellow fat-soluble pigments embedded in chloroplast or cyanobacteria internal membranes. Act as accessory pigments, transferring __ to chlorophyll a.
Carotenes- do not contain __.
- light energy
Cleavage of the __ at this point shown yields two molecules __. Oxidation of vitamin A yields __, the pigment involved in vision. __ attaches to the __ to form __. Orange-yellow __ is the most abundant caroten in chloroplasts.
- beta-carotene molecule
- vitamin A
- retinene x2
- protein opsin
__, a reddish carotene, is not found in chloroplasts, but gives the red color to tomato fruits.
Xanthophyll contains __.
__ is the pigment responsible for the yellow color of corn kernals.
__- red or blue, water-soluble pigments foundin cyanobacteria and red algae. Act as __, doing what?
__ is a blue __. It can transfer light energy directly to chlorophyll a. By themselves, they cannot do what?
- do photosynthesis, but they can capture and transfer light
__ is a red __. It transfers light energy to __, which then transfers the energy to chlorophyll a.
True or False: All pigments absorb the same wavelengths of light.
__ are very complex moleculces made of __. Some think that __ algins may be characteristic of young walls and the __ characteristic (or found only in ) of older walls.
- alpha 1-4 linked uronic acid units
- mannuronic rich
__ really includes a family or group of structural types with D-galactose-3,6 anhydro-D-galactose as the basic unit.
The major component of agar is called __, a 1-4 linked 3,6 anhydroalpha-L-galactopyranose and a 1,3 linked beta-D-galactopyranose.
What are the forms of cyanobacteria? Prominence of each?
- unicellular: minority (forms temporary colonies) [gelatinous matrix around them]
- colonial: normal way they look
- [some have really different shapes]
- filamentous: chain of cells/ no branching (some do; some don't) majority
What exactly is a filament?
trichome and sheath
-single chain of cells or branched
What is a trichome?
- in plants, it refers to hair
- in cyanobacteria, it refers to cells (chain of cells)
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