Unit 1 : Classification Of Life Flashcards
What are life’s emergent properties? — what factors determine if something is living or not? (6)
Life will have organization, structure = function, interdependence — it relies on other organisms to survive — energy flow, information flow, evolution (survival of the fittest gene mutations).
What are the 5 key features of life? (What are the basic units of energy, life and heredity?)
Cells are the basic unit of life
ATP is the basic unit of energy
DNA is the basic unit in heredity
Evolution and the differences in genomes explains the unity + diversity of life
All life is interconnected.
Who was the first person to classify organisms, and how were they classified?
Who followed this structure and was the first taxonomist? How were organisms classified?
Aristotle was the first person to classify organisms in a more holistic way, in the “great chain of being”and this was ordered based in levels of complexity.
Then carous Linnaeus (1735) was the first taxonomist and made the kingdom taxonomic hierarchy which was based on the similarities and differences in anatomical, physiological and nutritional characteristics. In other words, he based his organization off of morphology: which is the branch of biology that deals with the form of the living organisms and the relationships between them.
What is the order of the kingdom taxonomic hierarchy (specification of organisms wise)?
The closer you get to the bottom, the more (general or specific to species) you get?
Organisms that are close together for longer on the kingdom taxonomic hierarchy means what in relation to their genomes?
Remember: Dear King Philip Came Over For Good Spaghetti!
In Other words: domain, kingdom, phylum, class, order, family, genus, species. Every species is then a unique organism.
The closer you get to the bottom of the inverted period, the more specific to species you get.
The closer together for longer organisms are in the hierarchy, the more recently their genome diverged based on a mutation, and hence the more closely they’re related!
What element of an organism is an essential component to all of life? Because all organisms have this, how did its discovery help to relate different species and classify them?
All life stores genetic info in DNA molecules and uses ribosomes to translate that info into proteins so it can actually be used. It was discovered that some mutations cause no harm and hence they were kept and passed down, which is what causes the different traits in different organisms. So by comparing nucleotide sequences between organisms, it can be inferred which are most closely related. The more similar the sequences, the more DNA they share, and therefore the more recently they diverged from each other. This means they are more closely related on the kingdom taxonomic hierarchy!
What are the three domains of the three domain classification system? how are these domains discovered through the computer, and what are they based on?
The three domains are bacteria, archea and eukarya, and they were discovered by the input of molecular information which is way more precise than just physical qualities. These classifications are based on similarities and differences in this molecular information and therefore we can see where the different groups diverged, and where common ancestors are — in order to group them.
What are the four main differentiating characteristics of the domain bacteria?
1) Bacteria are prokaryotes meaning that they existed “ before the nucleus”. So no bacteria will have a nucleus.
2) They are unicellular, so they depend on a large surface area to volume ratio.
3) their cell walls are made of Peptidoglycan, which is a combination of amino acids and sugars. The cell walls coat the cells and protect them because the cells have to survive on their own.
4) they are small (1 to 5 µm).
What are the five main differentiating characteristics of the domain archea, and what is the one characteristic that separates them from the bacteria they look so similar to?
1) they are prokaryotic
2) they are Uni cellular
3) their cell walls are made of psendopeptidoglycan —> different sugars than peptidoglycan.
4) they are small (one to 5 µm).
5) they are found in extreme environments — this is the one characteristic that separates them from bacteria.
What are the four main characteristics of the domain Eukarya?
1) they are eukaryotic so they have a true nucleus.
2) they can be unicellular (like amoeba) and multicellular (fungi, plants, and animals).
3) some have cell walls and some don’t. The cell walls are made up of cellulose, pectin, chitin, and these are all arrangements of carbon atoms.
4) the cells are larger because they are more complex in the sense that they have many membrane bound organelles, which can work together to deliver nutrients in a more efficient fashion. so it is not as dependent on the surface area to volume ratio. These cells are 10 to 100 µm.
What are the similarities and differences between prokaryotic and eukaryotic cells? (4 both, 2 different)
Similarities: they have DNA, they have ribosomes —> which are different sizes, they have cell membranes, and they have cytosol, which is the fluid inside of the membranes in the cell.
Differences: prokaryotes have one circular DNA genome, as well as some tiny pieces floating around in the cytosol, and eukaryotes have multiple linear DNA molecules in the genome — which are stored in the nucleus. Eukaryotes have membrane bound organelles, which allows their cells to be much larger.
Why are prokaryotic cells so small and eukaryotic cells so much larger?
This is because of the surface area to volume ratio. Every time a cell doubles in size the surface area will increase by a factor of four, but the volume will increase by a factor of eight. This means that as cells get larger, the volume gets exponentially larger in comparison to the surface area and the surface area Available for nutrients to come in is not large enough for the volume of the cell. Once a cell reaches a certain size, the nutrients coming in through the limited surface area will not be enough to keep the cell alive, and it will die. Because you carry cells have membrane bound, organelles to deliver and transport nutrients, they don’t have to worry about this ratio as much because they can be sure the nutrients are getting to where they need to be rather than using diffusion — which is used in prokaryotic cells.
Why are prokaryotic cells so small and eukaryotic cells so much larger?
This is because of the surface area to volume ratio. Every time a cell doubles in size the surface area will increase by a factor of four, but the volume will increase by a factor of eight. This means that as cells get larger, the volume gets exponentially larger in comparison to the surface area and the surface area Available for nutrients to come in is not large enough for the volume of the cell. Once a cell reaches a certain size, the nutrients coming in through the limited surface area will not be enough to keep the cell alive, and it will die. Because you carry cells have membrane bound, organelles to deliver and transport nutrients, they don’t have to worry about this ratio as much because they can be sure the nutrients are getting to where they need to be rather than using diffusion — which is used in prokaryotic cells.
What is horizontal gene transfer?
Horizontal gene transfer does not occur in eukaryotes because DNA is so tightly packed away. But it does occur in prokaryotes. This is where genetic material is shared between two living prokaryotes just by swapping those genes through their membranes. Essentially, this isn’t following the normal mode of transfer of genes — vertical gene transfer through evolution — it’s just spontaneously appearing at one point in time, which could lead to a new species, if that gene helps that organism to survive in a changing environment.
What is the endosymbiotic theory? What benefits do both the host cell and the inner cell get from this relationship? What are the pieces of evidence for the endosymbiotic theory? (7)
The endosymbiotic theory is the belief that eukaryotic organelles were originally independent prokaryotic cells. It is believed that these independent cells were taken in by host cell, but not digested because that host cell realized these new cells were more efficient in helping then they were being digested by the host cell. Therefore, that cell was able to live inside the host cell and form a symbiotic relationship. The cells are what we call what we call mitochondria and chloroplasts today.
The inner cell (or the bacteria) no longer needed to protect its DNA because the host cell had everything it needed, and so much of it disappeared overtime. So, the bacteria received protection and nutrient sources brought straight to them by living inside the host cell. The host cell (or the archea) received a great source of ATP, and it used this excess energy from the bacteria to grow, evolve, and develop an end membrane system with these new organelles.
Evidence for this theory: mitochondria and chloroplast are the same size as modern prokaryotes, they have their own circular DNA molecule, even though most of the genome is mutated beyond function. This DNA shows that they originally were individual cells, since you need DNA to grow and live — to instruct that cell to carry out essential functions. As well, although the DNA was not originally in the nucleus, it is now due to horizontal gene transfer from bacteria to nucleus — this is something only bacteria can do! These organelles also divide by binary fission and not mitosis. Binary fission is how prokaryotes divide, but mitosis is how eukaryotic cells divide. Many other symbiotic relationships similar to this exist proving that is possible. As well, both C.P and M have a double membrane which should not be needed. but if they were engulfed via phagocytosis, then this would make sense as the membrane would surround them as they were taken in. Also, mitochondrial RNA is much more similar to prokaryotic RNA than it is to eukaryotic RNA. Lastly, they have 70 S ribosomes, which is the same as prokaryotes.
What are the two different sources of things that organisms need in order to survive that can help to classify them?
Organisms need a source of energy, and organisms need a source of carbon.
