hi everyone this is kim velazquez and as we're moving into organismal biology there are some basic biological terms that are important to review so some of you might be learning these terms for the first time and others of you have learned them throughout the semester probably at the very beginning of the semester and it's important to review those terms before moving into organismal biology i'm calling it organismal biology because if you're taking the general biology course you are moving into discussing all types of living organisms if you are in biology 102 then you are mostly just looking at those organisms that are human pathogens but either way these terms are very important to your understanding so the first thing to recall is the difference between a unicellular and a multicellular organism so unicellular as the term really specifies is a one-celled organism meaning the entire organism is made of just one cell and all the functions are carried out by that one single cell they can only get to a certain size and they usually have a short life span and no real specialization of different types of cells because there's only one cell so they can't really specialize they tend to be microscopic meaning you can't see them with the naked eye because they can't get big enough to be seen with the naked eye comparing that with a multicellular organism meaning that entire organism is made of more than one cell and those cells are usually specialized into different functions even with tissue layers and cells that are performing very specific functions for the organism they tend to be much larger obviously because they're made of more than one cell they tend to be macroscopic meaning you can see them with the naked eye and they definitely have a longer life span in general than the one celled organisms okay so examples of unicellular organisms obviously all bacteria are unicellular all protists are unicellular the difference is of course that bacteria are prokaryotic cells while protists are single celled eukaryotes so that means protists have a nucleus they have membrane-bound organelles they are far more complex in structure than the prokaryotic cells okay then some algae are single celled and then we have some fungi that are single solved mostly it's just the yeast the yeast are the single celled fungi and those are in the category of human pathogen obviously multicellular organisms far more complex so it would include animals plants and most fungi as fungi are multicellular by the way fungi is also correctly pronounced fungi also fungi and fungi so four different pronunciations of that term reproduction in organisms can either be sexual or asexual and this is going to be important as we start talking about organismal diversity and also as we talk about different human pathogens the mode of reproduction is important to understand if an organism has asexual reproduction it really means it just makes a copy of itself there is no joining of gametes to produce a zygote that then develops into the mature organism so yeast budding they are really just replicating their genome and then making an identical copy of themselves this is a protist again replicating its genome and then just splitting into to make an identical copy of itself so that's asexual reproduction compared with sexual reproduction where egg and sperm come together so there's a fertilization event that produces that very first cell the zygote so recall that both of these gametes the egg and sperm have the haploid number of chromosomes while the zygote has the diploid number of chromosomes and then that divides and divides and the cells specialize and eventually make the entire major organism so that's sexual reproduction i know none of these terms are really connected at this point but you will be using all of these terms to understand the organismal biology that's coming up so it's kind of a biological vocabulary review okay an autotroph versus a heterotroph an autotroph is an organism that makes its own food and we usually call those autotrophs producers because they're producing food so these would be plants and algae that carry out photosynthesis and they make carbohydrates for the rest of the food chain versus a heterotroph who has to eat an autotroph or someone who ate an autotroph so those are the consumers they get their energy by eating other organisms they cannot produce their own energy and it's all animals most bacteria and fungi are what are called heterotrophs so two different kinds of autotrophs photoautotrophs are what we're mostly familiar with so they get their energy from the sun and they carry out photosynthesis to make chemical energy in their cells and they're not being altruistic they're not doing it for the benefit of the rest of the food chain it just happens to turn out that way they're actually making it for themselves so they also have to carry out cell respiration as all living organisms do they just don't eat instead they make their own carbohydrates and then use those carbohydrates to carry out cellular respiration chemo autotrophs actually get energy by some other mechanism so they're getting it from chemicals so rather than using live energy they're using chemical energy and that's something we don't really talk about in this class but you will hear this term sometimes with reference to certain organisms okay so when we're looking at heterotrophs there are a lot of different levels of heterotrophs depending on where these organisms are in the food chain so herbivores would be what we call primary consumers so they're all consumers but depending on where they are on the food chain herbivores would be kind of the lowest level they eat plants and then carnivores eat animals who either ate a plant or ate another animal if you're an omnivore you eat plants and animals if you're detritivore you feed on dead material and if you're your decomposer such as bacteria and fungi you break down organic matter the difference is that you don't actually eat it if you're a decomposer so a decomposer would secrete some type of chemical to cause digestion of that material and in fact fungi actually digest outside of their cells and then absorb those nutrients into their cells so extracellular digestion is the characteristic of fungi okay it's important to understand different species interactions especially when we start talking about human pathogens so we're going to talk about different levels of symbiotic relationships in biological organisms so symbiosis means living together so bio is living and sim means together it's an arrangement between organisms of different species so if two organisms of the same species are living together that is not considered symbiosis symbiosis is when organisms of different species are living together in a close arrangement of some sort now those don't always benefit both organisms so we're going to look at the different categories of those symbiotic relationships and we're going to use a plus a minus and a zero to determine whether one of the organisms is benefited one is harmed or there's no effect so five major categories of symbiotic relationship predation parasitism competition mutualism and commensalism and so there's a picture of each of those here um sorry i'm laughing because i took this slide from the internet and some of these pictures just are kind of a funny example this one not funny okay so that's predation in this picture it appears that that seal is about to eat that penguin not a happy turnout for the penguin parasitism this ugly little tick here that's about to suck the blood of some organism competition these two cape buffalo fighting it out probably for a mate and this would be called intra-specific competition because they're actually um two of the same species so here i've just told you that symbiosis is of different species but a lot of competition in nature is between different species so species different species of organism competing for the same resources mutualism is a relationship that benefits both organisms and then finally commensalism benefits one and the other is unaffected so we're going to talk about these in more detail so predation that would be a plus minus relationship one of the organisms benefits so that's the plus and one is harmed in fact in predation the entire organism that is being harmed is eaten this minus that organism doesn't live okay so it 100 benefits the predator and it's at the expense of the prey the prey are consumed and really predators and prey have closely co-evolved because predators have to develop adaptations for catching their prey and prey have to have adaptations for escaping or hiding from predators so very closely related in terms of their adaptations very closely related in terms of population abundance and that's something that's closely studied in community ecology and population ecology okay so parasitism is a plus minus relationship also but in the case of parasitism a good parasite does not want to kill its host because you can't just run down the savannah and find another organism to feed from so if you're a parasite you're usually using you're living either on the outside of the host or the inside of the hose okay so an ectoparasite lives on the outside such as a tick or flea an endoparasite lives inside the hose such as a parasitic worm a protist a bacteria although we do have bacteria on the outside of our bodies too but most of those are symbiotic in a good way but a good parasite doesn't intend to kill their host they sometimes accidentally kill their host by really compromising the system of that host so much that the host dies but a good parasite doesn't want to kill their host it's too hard to find another home so if the host dies the parasite usually dies also parasites have evolved in amazing strategies for survival lots of specializations and a lot of them have really complex life cycles involving more than one host that we're going to talk about so this is an example of some specializations in a parasitic worm so this is a tapeworm and this is the region of the tapeworm called the scolex and you can see these hooks for attaching to the intestines suckers for attaching to the intestines they are colorless for the most part they don't have pigment because no need for pigmentation if you're inside an intestine they don't have eyes because you don't need to see in an intestine so these guys are very specialized for attaching and feeding in a host some other important terms related to parasitism a vector this is a very important term in looking at pathogens of humans a vector is the organism that transmits the pathogen but doesn't cause the disease itself okay so mosquito is the vector of the malaria parasite meaning the mosquito is what transmits the parasite to humans but it's not really the mosquito that's causing the disease it's the malarial parasite that's causing the disease so that's what a vector is an intermediate host is an organism that harbors the sexually immature form of the parasite sometimes called the larvae so the intermediate host is where that organism lives and then eventually gets transmitted to the definitive host and that's the host in which the sexual reproduction of that parasite will occur and most often that reproduction of that parasite will then lead to the definitive host transmitting that back to the environment where the intermediate host can pick it up again so lots of terms related to parasitism and you'll get more of this information as you go through the organismal diversity okay competition some um biologists would disagree with this but a lot of ecologists say that competition is a negative negative because in the absence of competition it's often thought that one or both of those species would be more successful than they are in the presence of competition and again in symbiotic relationships since we're usually talking about species that are different so two different species then this occurs when two species are trying to use the same resource so shelter food water soil nutrients so that's called inter-specific competition meaning between two different species inter means across and really one of the biggest principles in ecology is this principle of competitive exclusion saying that if two species are competing for a resource and that resource is limited meaning there's not an infinite amount of that resource then over time one species will use that resource more efficiently and eventually will eliminate the other in that location commensalism is interesting so commensalism is a plus zero because one organism is benefiting from the other okay but the other species is not being affected either positively or negatively and some biologists also have a problem with this because they say that it's impossible to not have some effect on the other organism but this is an example this moss is called an epiphyte it's hanging from this tree but it's not robbing this tree of nutrients or having any other noticeable adverse effect on the tree so the moss is benefiting and the tree is essentially not benefited or harmed so that would be the zero mutualism is the one that we've heard the most about probably when we think about symbiosis we think of a plus plus where both species benefit so this is the classic example of the clownfish living in the anemone the anemone stings other organisms but these cloud fish have developed a mechanism for not being stung by the anemone and i won't go into detail about that and there are a lot of theories on what the mutualistic benefit for both organisms really is you know it could range from shelter to these clownfish are protecting this anemone from other um predators that would kill it so this anemone is actually an animal it's not a plant there are a lot of theories about how these two benefit you know maybe it's that the fish can eat the leftover scraps that the anemone spits out after it's finished eating but either way they both benefit from this relationship one of the most interesting relationships i think that's mutualistic is that between the pollinator and the plant that it pollinates because this hummingbird has a very close relationship with this plant so close that its beak length is exactly that necessary to get the nectar from this flower and then it will visit another one of these flowers and without knowing it transfer pollen from this flower on this plant to the same species of plant in another location thereby carrying out pollination for that plant cross-pollination is a very important thing for genetic diversity in this plant it's a really beneficial relationship for both organisms because this hummingbird knows that it can go find food at this plant it has reduced competition for this resource if its beak is specialized to this plant and other hummingbirds don't have a beak that perfectly fits so now the species of hummingbird can really have this tight relationship with this plant also since it's only going to visit this particular plant species this plant ensures that its pollen is not going to be wasted on a different plant species that it will get delivered to another plant of the exact same species and there are hundreds and hundreds of examples of these very tight-knit relationships between a plant and its pollinators and you can see this little guy with the pollen on his beak that's a fantastic photo okay again some unrelated terms but these are all important so just reminding you the difference between aerobic and anaerobic so aerobic means with oxygen and anaerobic means without oxygen so this could be talking about modes of cell respiration or it could be talking about the lifestyle of that organism related to that if you have an obligate lifestyle it means you must do that whereas if you're considered facultative it means you can do that and there are a lot of different applications of these terms okay so for example obligate parasites are obligated to that lifestyle they must live inside a host or they will die versus faculty of parasites can live inside a host or they can be free living it also can relate back to those terms aerobic and anaerobic and especially when you're talking about bacteria there are facultative anaerobes so remember facultative means can and obligate means must so if you're facultative that means you can be this so you can survive in the absence of oxygen but you can also survive in the presence of oxygen your you can really be somewhat successful in either environment versus obligate if you're an obligate aerobic it means you must have oxygen you will die if you don't and if you're an obligate anaerobe you must have a condition with no oxygen in fact you're killed by oxygen so these terms are important when talking about bacteria in particular okay and then what is a pathogen a pathogen is a living organism or a non-living entity so viruses and prions are examples of non-living entities but it's called a pathogen if it's capable of causing disease so any organism or virus or prion so these would be the non-living capable of causing disease is what we call a pathogen and then not all organisms that are in the pathogen category always cause disease so if you're a true pathogen sometimes also called a strict pathogen it means you always cause disease even in healthy individuals and you're very associated with a specific and recognizable disease so if you're a bacteria that causes a specific disease such as tuberculosis and every individual who is infected with that bacteria is going to get the disease then you are a true or strict pathogen but some pathogens only cause disease in an individual that is immunocompromised or has some other illness that has made them prone to other pathogens and those are called opportunistic so those organisms gain access um usually due to some type of injury or the person is immunocompromised and now this pathogen that wouldn't otherwise harm them becomes harmful because it has the opportunity to do so okay that is a repeat of the same slide i'm not sure why i did that okay that's it those are the terms you need to know to move on to either just organismal diversity or in the case of bio 102 human pathogens thanks