Cyanobacteria Flashcards
Describe the endosymbiosis theory
Dr. Margulis was doing reserarch on the origin of eukaryotic cells. She looked at all the data about prokaryotes, eukaryotes, and organelles. She proposed that the similarities between prokaryotes and organelles, together with their appearance in the fossil record, could best be explained by “endo-symbiosis”.
[Endo = "within"] [Endocytosis = (cyto = cell) a process of 'cell eating' - cells are engulfed, but then usually digested as food....] [Endosymbiosis = cells are engulfed, but not digested...cells live together is a mutually benefitting relationship, or symbiosis]
Her hypothesis originally proposed that:
mitochondria are the result of endocytosis of aerobic bacteria
chloroplasts are the result of endocytosis of photosynthetic bacteria
in both cases by large anaerobic bacteria who would not otherwise be able to exist in an aerobic environment.
this arrangement became a mutually beneficial relationship for both cells (symbiotic).
(Cyanobacteria also engulfed into the cell – forming the chloroplast that we see in cells today
Cyanobacteria are prokaryotic (bacteria) )
How does symbiosis play a role in providing nutrients?
Bacteria provide fixed nitrogen to plants - an important biological reaction providing fixed nitrogen (diazotrophic bacterium).
Symbiotic cyanobacteria provide fixed nitrogen to marine microalgae Symbiotic bacteria provide vitamin B12 to marine algae
Do symbiotic bacteria play a wider role? Probably.
Root nodules – symbiotic with bacteria – undergo carbon Benson cycle central metabolic pathway.
(The Calvin cycle, Calvin–Benson–Bassham (CBB) cycle, reductive pentose phosphate cycle or C3 cycle is a series of biochemical redox reactions that take place in the stroma of chloroplast in photosynthetic organisms. … This set of reactions is also called carbon fixation.)
What organism first oxygenated the earth and when?
Photoautotrophic prokaryotes
- 3 billion years
- Early oxygenation of the earth
- Class Cyanophyceae contains 150 genera and 2,000 species (Hoek et al., 1995)
Give two examples of the genus of diazotrophic bacteria and draw a diagram of the cell processes allowing the conversion of nitrogen gas to fixed nitrogen.
Diazotrophs are bacteria and archaea that fix atmospheric nitrogen gas into a more usable form such as ammonia. A diazotroph is a microorganism that is able to grow without external sources of fixed nitrogen. Examples of organisms that do this are rhizobia and Frankia (in symbiosis) and Azospirillum.
Give some examples of the forms that cyanobacteria can be found in - the diversity.
What techniques can be used to demonstrate interactions between bacteria and cyanobacteria?
Bacteria isolated and identified using Gram stain and 16S rDNA and also FISH
How does gram staining work?
How Does Gram Staining Work?
The Gram stain procedure distinguishes between Gram positive and Gram negative groups by coloring these cells red or violet. Gram positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls, which retains the crystal violet these cells are stained with. Alternatively, Gram negative bacteria stain red, which is attributed to a thinner peptidoglycan wall, which does not retain the crystal violet during the decoloring process.safranin in the final staining process.
Cells are stained with crystal violet dye. Next, a Gram’s iodine solution (iodine and potassium iodide) is added to form a complex between the crystal violet and iodine. This complex is a larger molecule than the original crystal violet stain and iodine and is insoluble in water.
A decolorizer such as ethyl alcohol or acetone is added to the sample, which dehydrates the peptidoglycan layer, shrinking and tightening it. The large crystal violet-iodine complex is not able to penetrate this tightened peptidoglycan layer, and is thus trapped in the cell in Gram positive bacteria. Conversely, the the outer membrane of Gram negative bacteria is degraded and the thinner peptidoglycan layer of Gram negative cells is unable to retain the crystal violet-iodine complex and the color is lost.
A counterstain, such as the weakly water soluble safranin, is added to the sample, staining it red. Since the safranin is lighter than crystal violet, it does not disrupt the purple coloration in Gram positive cells. However, the decolorized Gram negative cells are stained red.
Describe the FISH technique.
Fluorescence in situ hybridization (FISH) is a molecular cytogenetic technique that uses fluorescent probes that bind to only those parts of a nucleic acid sequence with a high degree of sequence complementarity. It was developed by biomedical researchers in the early 1980s[1] to detect and localize the presence or absence of specific DNA sequences on chromosomes. Fluorescence microscopy can be used to find out where the fluorescent probe is bound to the chromosomes. FISH is often used for finding specific features in DNA for use in genetic counseling, medicine, and species identification
What reasons are there for studies on cyanobacteria intensifying?
- Cyanobacterial natural products have shown promise in drug discovery
- World is headed towards a bioeconomy using environmentally friendly biodegradable resources
- Failure by chemical synthesis and combinatorial synthesis (synthetic chemistry) to deliver lead compounds as drug leads. Searching for marine compounds is more expensive than searching for terrestrial compounds, however it is considered a better option after a lack of success elsewhere.
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Explain a biotechnological application of cyanobacteria in materials.
Polyhydroxyalkanoates or PHAs are polyesters produced in nature by numerous microorganisms, including through bacterial fermentation of sugar or lipids. When produced by bacteria they serve as both a source of energy and as a carbon store.
Synthesis of polyhydroxyalkanoates that are a substitute for non-biodegradable petrochemical based plastics
Major companies Metabolix Inc. (U.S.), Meredian Inc. (U.S.), Biomer (Germany), Tianjin GreenBio Materials Co. Ltd (China), Shenzhen Ecomann Technology Co. Ltd (China)
Explain a biotechnological application of cyanobacteria in materials.
Explain a biotechnological application of cyanobacteria in medicine.
Cyanobacterial natural products have shown potential as useful medicinal agents
- target tubulin and actin microfilaments
- modulate cell death and apoptosis in cancer
- target enzymes e.g. histone deacetylase
- antimicrobial and antifungal activities
- structural templates of new drug leads
A lot of chemists study cyanobacteria because they are very good at producing novel compounds and building blocks.
What study extracted which therapeutic compound from cyanobacteria?
An examination of an organic extract of the cyanobacterium Lyngbya majuscula, collected from Wasini Island off the southern Kenyan coast, led to the isolation of the known cyclic depsipeptide antanapeptin A (1), recently isolated from a Madagascan collection of L. majuscula, and a new bioactive cyclic depsipeptide, homodolastatin 16 (2). The structures of these two compounds were determined from NMR and mass spectrometry data. Homodolastatin 16, a higher homologue of the potential anticancer agent dolastatin 16, exhibited moderate activity against oesophageal and cervical cancer cell lines.
A homologue (also spelled as homolog) is a compound belonging to a series of compounds differing from each other by a repeating unit, such as a methylene bridge −CH.
What are NRPS?
Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be made by bacteria inside these organisms.[1] While there exist a wide range of peptides that are not synthesized by ribosomes, the term nonribosomal peptide typically refers to a very specific set of these as discussed in this article.
Nonribosomal peptides are synthesized by nonribosomal peptide synthetases, which, unlike the ribosomes, are independent of messenger RNA. Each nonribosomal peptide synthetase can synthesize only one type of peptide.
why are scientists interested in NRPS?
They produce lots of antimicrobial or drug-like peptides.
