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Marr Bio 2
Question | Answer |
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Viruses | Non-cellular infectious agents that have two basic characteristics: Not capable of reproduction without a host cell |
Virus structure include: | Nucleic acid core- can be DNA or RNA Capsid (Protein coat)- consists of numerous protein subunits organized into rod-like or many sided shape. |
Retroviruses | store genetic information in the form of nucleic acid known as RNA |
Lysogenic viruses | reproduce by inserting their DNA into the DNA of the host cell |
Bacteriophages | viruses that infect bacteria |
Viruses in the Marine community: | -They are very common in marine waters and can infect everything from plankton to marine mammals - Lysis (bursting) of viral infected cells release large amounts of organic matter to be utilized by other organisms (DOM) |
Characteristics of prokaryotes: | -No nucleus -Single chromosome (normally circular) - some also with plasmids -Cell wall, but different in biochemical structure |
More about Archaea | -They are primitive organisms(oldest fossil 3.8byo) -They can tolerate wide ranges in temperature, salinity and even desiccation (drying out) -Can be found in many areas including near hydrothermal vents and salt flats (two very extreme environments) |
Bacteria: | -A variety of shapes including spirals, spheres, rods and rings -Cell wall structure is semi-rigid, but permeable; most with cell wall -Size is normally microscopic, but a few are large -Wide variety of metabolic types |
Special Features of Bacteria | One of the most important jobs of bacteria in the marine community is to break down dead organic matter – this forms detritus, which are minute particles of organic matter now available as nutrition for other organisms |
Cyanobacteria is a group of | photosynthetic bacteria |
Stromalites | massive calcareous mounds formed by cyanobacteria, have been found that are 3 billion years old |
Photosynthesis | derive energy from light |
Chemosynthetic | derive energy from chemical compounds |
Heterotrophs | derive energy from organic matter by respiration |
Diatoms | -Photosynthetic -Yellow-brown color in life is a result of photosynthetic pigments, chlorophyll A and C and carotenoids -Shell of silica called a frustule -Most important primary producer -Mostly solitary and unicellular |
More info on diatoms | -Around half of the 12,000 known species are marine -Mostly planktonic -Store excess energy as an oil which aids in buoyancy -Tiny pores in shell used for gas/nutrient exchange |
Toxins in Diatoms(domoic acid): | can accumulate in the tissues or organisms that eat diatoms such as shellfish and small fish -Larger organisms that eat these shellfish or small fish can become ill or die from this accumulated toxin |
Reproduction in Diatoms: | - Reproduce mainly by cell division(asexual) - In this type of reproduction, the cell divides and each cell gets 1/2 of the frustule. |
Due to cell division in Diatoms | diatoms get smaller each time they reproduce -To restore they must either sexually reproduce or cast off the frustule and secrete a new frustule |
Dinoflagellates | -Mostly marine -Mostly photosynthetic,some ingest particles -Each species has unique shape reinforced by plates of cellulose |
More about Dinoflagellates: | - 2 flagella in grooves on body that produce motion Also reprod. by cellular division -Some are bioluminescent -A few lack chloroplasts and live as parasites in other organisms |
Zooxanthellae (genus Symbiodinium) | are important dinoflagellates that live in a symbiotic relationship with corals, sea anemones and other organisms (many of these host organisms have little or no growth without their symbiotic partner) |
Diatoms and dinoflagellates can go through periods of rapid growth known as | “blooms”This is a result of high levels of nutrients in the water These blooms can be harmful to marine organisms and even people at times |
Red Tide | Species of dinoflagellates that reproduce in large numbers and produce a reddish algal bloom. |
Pfiesteria is a dinoflagellate that | produces very serious toxins that can cause massive fish kills, harm shellfish and impair the nervous systems - Was discovered near the Outer Banks in North Carolina |
Silicoflagellates | Star-shaped internal skeleton of silica Two flagella of varying lengths |
Coccolithophores | Ornate shells of calcium carbonate |
Foraminiferans (forams) | -Exclusively marine -Found on sandy or rocky bottoms -Shells of calcium carbonate -Pseudopods (false feet) extend through pores in the shell where they are used to capture food particles like phytoplankton |
Foraminiferans can also | be important contributors of calcareous material on coral reefs or sandy beaches |
Radiolarians | -Planktonic, mostly microscopic, although a few can reach large sizes -Shell of silica -Like forams, they use pseudopods that extend through pores in the shell where they are used to capture minute food particles such as phytoplankton |
Ciliates | -Cilia present for locomotion -Most live as solitary cells -Some build shells made of organic debris -May live on hard substrate -Some are planktonic -Some are parasitic on fish |
Fungi | -Eukaryotic and mostly multicellular -Heterotrophic -Most of the 1500 of marine species are microscopic |
Like bacteria, many fungus break down dead organic matter into | detritus |
Some fungus live in symbiosis with cyanobacteria, these are known as | lichens |
Marine lichens often live in | wave-splashed areas of rocky shorelines and other hard substrate |
Marine algae are | important primary producers (photosynthetic) These algae are called by a generic term “seaweeds” or more formal term macroalgae |
The body of a macroalgae is known as a | thallus. This thallus can be simple or more advanced in its structure. |
In some algae, there are: | Blades – leaf-like structures Stipes – stem-like structures Holdfast – root-like structures |
Some algae also possess pneumatocysts, | gas-filled bladders used to keep the blades near the water’s surface where more light is available for photosynthesis |
Two primary examples of marine algae with pneumatocysts are | the giant kelp, Macrocytes spp. and sargassum weed, Sargassum spp. |
Like plants, algae exhibit a life history marked by | an alteration of generations |
To summarize, in the alternation of generations: | A gametophyte stage produces gametes (eggs and sperm) that will fuse to become a zygote. This zygote then develops into a second stage, the sporophyte, that produces spores. These spores develop into the gametophyte stage and the cycle begins again |
Many algae also reproduce asexually by a means called | vegetative growth |
In the Process of vegetative growth: | an algae reproduces new individuals that are genetically identical to the parent algae. |
algin or alginate | is an extract of brown algae that is used as a emulsifier in dairy products such as ice cream and cheese |
Another example of an extract is the carrageenan harvested from red algae. Carrageenan is also used as a | thickening agent in dairy products such as yogurt, milkshakes, etc. |
Agar is a second extract from red algae. Agar is used to | culture microbes in the health care industry. It is also used as a thickener in foods, used as a filler in pharmaceuticals and cosmetics and to protect canned meats |
Green algae (Chlorophyta) | -Thought to be ancestor of land plants ~ 7000 species;< 1000 are marine -Found worldwide -Some coralline (produce calcium carbonate,) -Chlorophylls A and B as well as carotenoids -Store excess energy as starch -Cellulose in cell walls |
Brown algae (Phaeophyta) | ~ 1500 species, almost all marine -Some microscopic, most large Prefer shallow, cold waters -Contain chlorophyll A and C and fucoxanthin -Typical body of holdfast, stipe and blades -Source of algin -Examples: kelp |
Notable Brown Algae: | -Kelps are the largest of Algae (some species up to 100 ft in length -Amongst the most productive marine habitats |
Sargassum is a species of brown algae found in the | Atlantic between North America and Europe as well as the Gulf of Mexico. - Their floating mats provide habitat for countless fish |
Red Algae (Rhodophyta) | ~ 4000 species, almost all marine -Prefer deep cold waters or warm, shallow waters -Some are coralline (produce calcium carbonate, Ex: Corallina -Contains photosynetic pigments, chlorophyll A and D and phycobilins |
Angiosperms: | True plants that have true leaves,stems, roots and conducting tissue |
Plants that do live in marine communities must have | a mechanism for dealing with salinity |
Seagrasses | ~60 species exist,mostly tropical Small flowers.Pollen is carried by water. Tiny seeds produce by fertilization are carried by water currents or in the feces of animals that consume them. Primary proliferation is through rhizomal extension. |
Seagrasses are known for: | -exhibiting rapid growth an being a food source and habitat |
Eelgrass | The most widely distributed of the seagrasses where it is widely distributed in shallow water bays and estuaries. |
Salt marsh Plants | plants bordering shallow bays and tidal creeks. |
Cordgrass Spartina | the predominant salt marsh plant is in the grass family. -is only exposed to saltwater at high tide. -habitat for young marine animals - Little is directly consumed by herbivores. |
Detritus serves as | a nutrient source for countless organisms. |
Spartina plants possess | salt glands to help deal with excess salt |
Mangrove trees | -70 species only on tropical and sub-tropical -Like Spartina, they only tolerate partial salt water submergence |
Red mangroves | have a thick network of prop roots that are heavily exposed at low tide |
Black mangroves | are characterized by distinct erect projections from the roots (called pneumatophores) that extend up to 20 cm from the substrate |
Seeds of the red mangrove | germinate while still attached to the parent plant and develops into seedlings up to 1 foot in length before falling from the parent tree. |
Spartina plants possess | salt glands to help deal with excess salt |
Mangrove trees | -70 species only on tropical and sub-tropical -Like Spartina, they only tolerate partial salt water submergence |
Red mangroves | have a thick network of prop roots that are heavily exposed at low tide |