hi everyone welcome back today's video will be about three domains of life scientifically all life is divided into three domains they are eukarya archaea and bacteria the above diagram shows these three categories and how they originated from a common ancestor what is interesting to note is that the three categories did not originate at the same time you can see that the common ancestor mutated enough to create two different domains of which bacteria was one later the other group mutated further to divide into two more domains giving rise to archaea and eukarya therefore aqia and eukarya have their own common ancestor as well interestingly what we call prokaryotes refer to all the organisms found in the archaea and bacteria domains this form of classification was based on modern biochemical and genetic technologies earlier we used a system called the five kingdom system to categorize life in this archaean bacteria were grouped together the group was called monera the five kingdom system consisted of these categories monera protists fungi plants and animals under the new system which is the three domain system organisms in the monera category were divided into bacteria and archaea while organisms in the protists fungi plants and animals were grouped into eukarya now let's talk about the three domains eukarya eukarya might be the group that you are most familiar with eukaryotic organisms can be single or multicellular as mentioned before these include all protests fungi plants and animals regardless the main defining feature of eukaryotic organisms is that they contain membrane-bound nucleus additionally many organelles carried by these cells are membrane bound as well examples of membrane-bound organelles include the nucleus mitochondria ribosomes galga apparatus the endoplasmic reticulum lysosomes and chloroplasts in the case of plants akia aqia are single-celled organisms they are unique because they share similarities with eukaryotes and bacteria this makes sense when you look at how each domain developed from the common ancestor let's consider how archaea is similar to eukaryotes and bacteria archaea is similar to eukaryotes in the following ways they start mrna translation with methanol associate their dna with histone proteins they contain similar rna polymerases they have similar dna replication mechanisms and they share several metabolic pathways archaea similar to bacteria in these following ways they're visually similar they are both prokaryotes that is they do not contain membrane bound nucleus or other membrane bound organelles they contain a single circular chromosome they reproduce via binary fission budding and fragmentation and they contain flagella for movement although they're similar to eukaryotes and bacteria they are also unique in their own ways for instance they have a reputation for being extremophiles this means that they can withstand extreme environmental conditions that are generally considered harsh for example high temperature environments high pressure environments and environments with high salinity however scientists recently also have found these organisms in a variety of normal environments like our skin another notable characteristic of archaea is that they can use multiple sources of energy for instance some are photosynthetic and use light carbon dioxide and water for energy production others are chemosynthetic and use inorganic compounds like ammonia for energy production bacteria similar to archaea bacteria are single celled and black membrane bound organelles bacteria were the first prokaryotic cells to be discovered as such when archaea were discovered bacteria were referred to as eubacteria meaning true bacteria bacteria share many environments with us therefore humans have different types of relationships with bacteria some of them are symbiotic while others are pathogenic the best example of a symbiotic relationship between humans and bacteria is the relationship we have with our gut microbiome the human gut is home to about 1 trillion bacteria some bacteria are good and some are bad but overall the net result is a positive both the human as well as the bacteria inhabiting the human gut are benefited in this type of relationship for example the gut bacteria produce vitamin k and b7 also known as biotin vitamin k is an important component in the blood clotting process benefit to bacteria is that humans provide them with food and also a place to live some bacteria are pathogenic and therefore cause disease these do not provide any benefit to the host and take advantage of the horse they can grip inside the cells or outside the cells if the former they are called intracellular if the latter they are called extracellular these bacteria can also be gram-positive or gram-negative both types are pathogenic to the human body because their cell walls contain toxic components that can cause disease for instance they play a central role in the pathogenesis of bacterial septic shock in humans this is a lethal condition that involves the collapse of the circulatory system and multiple organ failure however gram-negative bacteria are considered to be the primary pathogen this is because of the unique structure that allows them to be resistant to treatment such as antibiotics that's it for this video i hope this was helpful for you if you have any questions please comment them down below you can also go to our website at www.clarifyscienceconcepts.com for more information if this was helpful for you please make sure to like and subscribe that really helps at the channel see you in the next video bye