Pearson+ LogoPearson+ Logo
Start typing, then use the up and down arrows to select an option from the list.


Learn the toughest concepts covered in Microbiology with step-by-step video tutorials and practice problems by world-class tutors.

21. Principles of Disease

Symbiotic Relationships


Symbiotic Relationships

Play a video:
Was this helpful?
in this video, we're going to begin our lesson on symbiotic relationships. And so of course we know that different organisms can survive in the same environment, which means that it's likely that different living organisms, for example, humans and microorganisms are going to interact with each other to form what we referred to as symbiotic relationships. And so the term symbiosis is a term that refers to the specific biological interactions or the specific biological relationships between two different Organisms or two different species. And so really there are three forms of symbiotic relationships that we have number down below 12 and three. And so the three forms of symbiotic relationships are mutual ism commence cell is um and parasitism now mutual is um is going to be a relationship between two organisms, where both organisms are going to benefit from. The relationship commence dualism is a relationship between two organisms where one organism is going to benefit from the relationship, but the other organism is going to be another affected by the relationship, meaning that they are not going to be affected and that means that they neither are going to benefit nor are they going to be harmed by the relationship. And so they remain unaffected. And then the third type of symbiotic relationship is parasitism. And in parasitism it describes a relationship between two organisms where one organism is going to benefit from the relationship at the expense of the other organism, meaning that the other organism is going to be harmed by the relationship. And so all pathogens or disease causing agents are categorized as parasites. And so if we take a look at our image down below which we'll see is a table that can help us better understand the three types of symbiotic relationships. And so notice that we have these three columns. We have the interaction between two organisms, the relationship type and a biological example of the relationship. And so when there is an interaction between two organisms where both organisms benefit from the relationship, we referred to this as a mutual ist IQ relationship or just mutual ISM. Species A will benefit and Species B will also benefit. For example, flowers have a mutual mystic relationship with honeybees and this is because the flowers are actually going to get pollinated by the activity of the honey bees and the bees are able to collect nectar for making honey from the flowers. And so by having this biological relationship between the flowers and the bees, both organisms are able to benefit from the relationship. And so we call this mutual isM. Now, if there is a an interaction between two organism where only one organism benefits and the other organism is unaffected, then we refer to this as commence cell is um And so incrementalism notice that species A will benefit However, Species B is unaffected, meaning that they will neither benefit nor be harmed. And so an example of a commence ballistic relationship is the relationship between barnacles and whales. And so these barnacles are organisms that really can't move much on their own. However, they can stick to whales and use whales as transportation, which ultimately ends up benefiting the barnacles. And so the barnacles are able to get food from that transportation provided by the whales and the whale is actually unaffected by the barnacles. So the whale is neither harmed nor significantly benefits from the barnacles. And so the whale remains unaffected and the relationship between the barnacles and the whales would be commence Eliza. Um And then last but not least if there's a relationship between two organisms where one organism benefits from the relationship, but the other organism is harmed by the relationship. We refer to this as parasitism. And so parasitism noticed that Species A will benefit however, Species A. Is benefiting at the expense of Species B who is being harmed, for example, ticks and dogs have a parasitic relationship. And this is because the tick will actually feed on the dog's blood and that benefits the tick because the tick is able to get its nutrients from the dog's blood. However, the dog, on the other hand is losing blood which is actually going to be harmful to it. And it could also get an infection from that relationship. And so the tick is going to benefit but at the expense of the dog which is going to be harmed. And so this here concludes our brief lesson on symbiotic relationships and the three types of symbiotic relationships. Mutual ism commence realism and parasitism and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.

Organisms that interact and live together on a permanent basis are in a relationship termed:


A relationship between two organisms in which one partner benefits and the other is harmed is termed:


Which of the following is an example of a commensal relationship?


Our microbiome is composed of a variety of microorganisms that live within and on our bodies. Research has shown our microbiota protects us against infectious pathogens, creates vitamins and minerals we need, and helps us digest our food. We act as a safe residence and food source for our microbiota. The relationship humans have with their microbiome could be described as?

a) A commensal relationship.

b) A resident relationship.

c) A mutual relationship.

d) A parasitic relationship.