1 Section 2.2: Unicellular Organisms (Micro-organisms)
2 Micro-Organisms Micro-organisms are: unicellular living organismstoo small to be seen with the unaided eye (only visible under microscope) also called microbes carry out all life’s functions, i.e. a single cell is responsible for feeding, digesting, excreting, and reproducing made up of three main types of micro-organisms: bacteria, protists, fungi
3 Size of Micro-organismsMicroorganisms can range in size from very small, such as these bacteria on the point of a pin….. Micro-organisms can range in size from very small, such as these bacteria on the point of a pin…..
4 …. to exceptionally large…..to exceptionally large. Some bacterial cells can be the size of a fly’s head. to exceptionally large. Some bacterial cells can be the size of a fly’s head.
5 Microorganisms are everywhere in between as well…Most unicellular organisms require liquid water in order to be active and thus, are confined to bodies of water (salt water and fresh water) and the soil. Microorganisms therefore inhabit diverse habitats ranging from… very salty environments such as the Great Salt Lake…. (orange color are salt loving bacteria) to deep sea vents at the bottom of the ocean (white on column)… to very hot environments such as this hot spring (orange). Microorganisms are everywhere in between as well…
6 Another environment in which unicellular organisms can grow is within the internal environment of multicellular organisms. Here, they often occur as parasites or agents of disease.
7 Bacteria Bacteria is: among the most primitive and also the most plentiful organism on Earth said to be very successful because they have survived and changed little over several billion years. single celled, no nucleus, no mitochondria, and no ribosomes (i.e. different from animal and plant cells) can be both helpful and harmful We will start with bacteria. One of the defining characteristics of bacteria is that they are always single celled and do not have a nucleus. There are many bacteria that are both helpful and harmful to us, as you will see in the following slides. To start off with, the statement can be made that bacteria engage in chemical warfare with each other, and we as humans indirectly benefit from this fact. Bacteria compete for food (usually whatever they are growing on), and in order to keep other bacteria off their food supply, some bacteria release antibacterial toxins around them. This damages or kills the other bacteria, and allows the toxin producing bacteria to maintain control over it’s food. We as humans have learned to take advantage of these chemicals to treat bacterial infections. Streptomycin is an example of such an antibiotic.
8 Examples of Helpful Bacteria:CO2 Waste Food nutrients Biodegradation Dead organic matter Respiration One example of a bacteria that we would not be here without is cyanobacteria. There are other bacteria that are helpful to us as well. For instance, this is a picture of the carbon cycle. Remember, carbon is an important part of many organism’s structure as well as their ability to function. Animals such as this horse eat carbon in the form of vegetation and produce waste. Many types of bacteria can break that waste down further in a process called biodegradation. This makes any carbon or nutrients in the waste available again to plants for growth and functioning. Humans have found a way to use such bacteria to clean up oil spills. We can spray bacteria which will biodegrade the oil on these rocks and decrease its toxic nature. Many types of bacteria can break that waste down further in a process called biodegradation
9 Examples of Harmful Bacteria:Tuberculosis Anthrax Lyme Disease Pneumonia Tuberculosis is a bacterial infection in the lungs. The bacteria cause tubercles in the lungs, which, when they rupture, turn into cavernas tuberculosas. Eventually the entire lung is degraded by these small caverns. These are pneumonia bacteria that cause fluid buildup in the lungs and difficulty breathing. Treatable with antibacterial drugs. And of recent fame, anthrax. Anthrax is particularly dangerous because it can form endospores that are resilient to drying and lack of nutrients. This means that anthrax can be distributed in a powder form. Ticks spread bacteria responsible for Lyme Disease
10 One of the most dangerous diseases caused by bacteria is the bubonic plague.25% of world population dies One of the most dangerous diseases caused by bacteria is the bubonic plague. The original hosts of the bubonic plague are rats. The plague is spread between rats by fleas that live on rats and suck their blood for food. Some rats carry the plague without dying. Others are susceptible and quickly die. When a rat dies, the fleas on that rat look for new hosts. If a human happens to be near, they will jump on the human. When they try to bit the human, they transfer bubonic plague. Symptoms of bubonic plague include swollen lymph nodes in the neck, armpit or groin area. At one time these nodes were named “bubos”, hence the name bubonic plague. During the height of its infection, the plague killed 25% of the worlds population. This graph shows the 3 of deaths over a two month period in London in As you can see, almost 50,000 people died in that single two month period. The bacteria that cause plague have had a tremendous impact on humanity.
11 2.Protists Eukaryotic cells: has a nucleus surrounded by a nuclear membrane. Contain organelles such as rybosomes, mitochondria, and lysosomes Two Types: Plant-like or Animal-like Plant-like: containing chloropyll and producing their own food. Example: Diatoms and Euglena Animal-like: feed on things living or that were once alive, can’t make their own food. Examples: Amoeba and Parmecium Many protists can be found in pond water We have talked about characteristics that define bacteria, as well as helpful and harmful bacteria, so let’s do the same for the second major type of microorganism, protists. Protists can be either single or multi-celled, and unlike bacteria, most protists have a nucleus (DNA sack). Some protists can produce their own food through photosynthesis, others consume food. Local ponds are a great place to find protists. Like bacteria, there are both helpful and harmful protists.
12 Diatoms Plant-like Protist: contain chlorophyll and can make their own food Found in both fresh and salt water Encased in two tiny shells which are join together Come in many different shapes These are examples of diatoms, important members at the bottom of the food chain. Diatoms come in many different geometric forms.
13 Euglena Has features of both plant-like and animal-like cellsIf lots of sunlight, it acts like a plant and makes its own food If reduced sunlight, acts like an animal and begins feeding on smaller cells Here is a peculiar example of a microorganism that is both and autotroph and a heterotroph, Euglena. It can use the two small flaggela-like structures on the upper left to search for food, or it can produce food as an autotroph does, through photosynthesis (use light energy to capture CO2 from the atmosphere). Because it can use a mixture of these two styles of gathering food, it is called a “mixotroph”. Can anyone speculate on what kind of environment Euglena would be best suited for? (A variable environment: when food that can be ingested is scarce, the Euglena can resort to producing it’s own food through photosynthesis)
14 Paramecium Animal-like Protist Uses cilia to moveUses cilia around its oral groove to create a current that draws food in Main source of food is bacteria and other smaller cells Some have small hair around their outer surface that beat back and forth to provide movement (hairs at outer edge).
15 Amoeba Animal-like ProtistBloblike organism that changes shape as it moves Moves by stretching out a branch of cytoplasm called pseudopod Pseudopod achors to an object and drags the rest of the amoeba towards it Uses pseudopod for feeding Still others move by using pseudopodia (“false foot”), which are extensions of the microorganism’s membrane (skin). The microorganism extends a pseudopodia, and then the rest of the organism flows into it. Some microorganisms also use pseudopodia to surround and ingest food particles. Because they must seek out and ingest food for both energy and carbon, these microorganisms are animal-like.
16 Examples of Harmful Protists:Red tide (Dinoflagellates) Some dinoflagellates, for unknown reasons, produce potent toxins. These toxins can be dangerous when dinoflagellate populations skyrocket to form red tides. The toxins enter the food web when higher organisms consume dinoflagellates. When humans eat seafood that has once fed on toxin-producing dinoflagellates, we get sick. One harmful protist that is extremely common is giardia. It causes diarrhea and dehydration. It can be found in many freshwater streams and lakes, and is the reason why it is so important to filter or iodize drinking water when camping. The pioneers of Utah experienced major problems with giardia. Perhaps the most famous harmful protist is plasmodium, which is responsible for malaria. Plasmodium has two different hosts. A mosquito becomes infected with plasmodium when it feeds on an infected human host. The plasmodium then undergoes part of its life cycle in the mosquito. It is then spread to other humans when the infected mosquito tries to feed again. After it enters the human, plasmodium completes its life cycle. Malaria has killed millions of people throughout history and continues to do so today. Human blood cell infected with Plasmodium
17 3. Fungi Singular is Fungus Can be unicellular or multi-cellularNeither plant nor animal but has characteristics of both Consume food by absorbing nutrients from whatever they are growing on Examples: bread mould, mushrooms, ringworm, dutch elm disease, athletes’s foot Now that we have learned about Protists, we are ready to move on to the third major group of microorganisms, the fungi. Fungi are neither plants nor animals, but have characteristics of both. However, they do consume food by absorbing nutrients from whatever they are growing on.
18 Yeast One of the few uni-cellular fungiDoes not have chlorophyll and must rely on other organisms for energy Yeast is an example of a single celled fungi that plays an important role in the production of a variety of human foods. Yeast helps bread rise, flavors cheese, and is crucial for making wine and beer.
19 Fungal production of an antibioticPenicillin is a toxin that is produced by penicillium fungus for the purpose of protecting its food source. We have learned to use this antibiotic substance to control bacterial infections in our own bodies. The discovery of such antibiotic substances has been incredibly important to human health.
21 Summary of PresentationMicroorganisms Anything too small to see without magnification 3 types of microorganisms Bacteria, protists, fungi 2 major ways to get food Plant-like (make it), Animal-like (consume it) Plant-like Gets food (carbon) from the atmosphere (CO2), more plant-like, known as producer. Animal-like Gets food by ingesting other things, more animal like, known as consumer. Microorganism size Range from very small to large (fly’s head) Microorganism habitat From bottom of sea to Salt Lake and everything in-between (including inside animals/insects/people) Movement Some are stationary, others move by cilia (small hairs), flagella (longer tail) or pseudopodia (extensions of outer membrane)