Classification Flashcards
What is biodiversity?
A measure of the variety of different organisms and their genetic differences
What is taxonomy?
The science of describing, classifying and naming living organisms
What is another word for physical appearance and who put organisms into groups based on this?
- morphology
* aristotle
What are analogous features?
Features that look similar or have the same function
What are homogolous structures?
Structures that genuinely show common ancestry
What are the main taxonomic groups from the largest to smallest?
Domain, kingdom, phylum, class, order, family, genus and species
What are the three domains?
Archaea, bacteria and eukaryota
What kingdom does the archeae domain contain?
The archaebacteria: ancient bacteria thought to be early relatives of the eukaryotes. Often found in extreme environments
What kingdom to do the bacteria domain contain?
The eubacteria: they are the normal bacteria we think of
What are the four eukaryotic kingdoms?
- protocista: very diverse group of microscopic organisms. Some are heterophs (have to ear orhwr orgamisms), some are autorophs (they make their own food by photosynthesis. Examples include amoeba and chlamydomonas
- fungi: all heterophs. They have chitin in their cell walls
- plantae: almost all autotrophs, include mosses, ferns and flowering plants
- animalia: all heterotrophs that move their whole bodies around during at least one stage of their life cycle. Include the invertebrates and vertebrates
Who developed the first Scientifically devised classification system?
Carolus Linnaues
Linnaeus developed the binomial system. What is it?
In the binomial system every organism is given two latin names. The first name is the genus name and the second is the species name
What are the rules to writing binomial names?
- use italics
- the genus name has an upper case letter and the species name has a lower case letter
- after the first use binomial names are abbreviated to the initial of the genus and then the species name e.g. H. sapiens
What is a genus?
A group of species that all share common characteristics
What was the definition of species originally developed by Linnaeus?
A morphological species concept based soley on the appearance of the organisms he observed
What are organisms that show sexual dimorphism and what could they be thought to be in a morphological species model?
- they show a great deal of difference between the male and female
- they could be thought to be different species in a morphological species model
What is the most widely used definition of a species?
A group of organisms with similar characteristics that interbreed to produce fertile offspring
What are the advantages and limitations of defining species as a group of organisms with similar characterisitics that can interbreed to produce fertile offspring?
- it overcomes issues such as sexual dimorphism
- however not all of the organisms in a species can interbreed to produce fertile offspring because they live in different areas
What are the two slightly more sophisticated definitions of species based upon reproductive capability?
- a group of organisms with similar characterisitics that are all potentially capable of breeding to produce fertile offspring
- a group of organisms in which genes can flow between individuals
What is molecular phylogeny?
The analysis of the genetic material of organisms to establish their evolutionary relationships
What is the ecological species model?
Based on the ecological niche occupied by an organism. This is not a robust way of identifying species as niches may vary and many species occupy more than one niche
What is the mate-recognition species model?
A concept based on unique fertilising systems including mating behaviour. However many species will mate or cross-polinate with other species and may even produce fertile offspring
What is the genetic species model?
Based on DNA evidence. It will become the main way of classifying organisms but people still have to decide how much genetic difference makes two organisms a different species
What is the evolutionary species model?
Based on shared evolutionary relationships between species. In this model, members of a species have a shared evolution and are evolving together. This is biologically sound but not always easy to apply
What are the limitations of species models?
1) finding the evidence -many living species have never been observed mating and setting up breeding programmes is time consuming and expensive
2) plants of different but closely related species frequently interbreed and produce fertile hybrids. It’s hard to say when the hybrids should be regarded as seperate species
3) many organisms do not reproduce sexually
4) fossil organisms cannot reproduce and normally do not have accessible DNA but still need to be classified
What now plays a major role in classification and how?
Information technology helps scientists to classify from simple identification apps to the prospect of instruments that will be able to identify DNA in the field
What is the natural history museum doing to reduce the time spent searching the handwritten or typewritten index cards of species that were identified many years ago?
Developing VIADOCS to scan and read the card archives and convert them into an internet - based database that scientists all around the world will have access to
What is DNA sequencing?
The base sequences of all or part of the genome of an organism are worked out
What does DNA sequencing lead to and what is this?
DNA profiling which looks at the non-coding areas of DNA to identify patterns
How can DNA sequencing and profiling help identify relationships between individuals and even species
Because we can look at the paterns in them and compare the similarity
What is bioinformatics?
The development of the software and computing tools needed to organise and analyse raw biological data, including the development of algorithms, mathematical models and statistical tests that help us to make sense of the enormous quantities of data being generated
Why is it difficult to identify species from their phenotype?
- Because conditions can result in major differences in appearance of individuals of the same species
- however some species will look the same but have different phenotypes such as the eight different species of Fusarium pathogens which were initially thought to be just one species
What is the caviar con?
- the most expensive caviar comes from the eggs of the Beluga sturgeon
- scientists developed a series of DNA profiles for different sturgeon species
- they then ran DNA profiles on lots of tins of beluga caviar and discovered that around 25% of them contained the eggs of other less prestigious species
What are the large groups of scientific organisations that are developing DNA barcoding as a global standard for species identification and what does this involve?
CBOL, IBOL, ECBOL. This involves looking at short genetic sequences from a part of the genome common to particular groups of an organism
Will bar coding replace traditional taxonomy?
No but it’ll support it
What does it mean the more differences there are in the DNA of two individuals?
That it’s been a longer time since they shared the same ancestor
When does DNA start to decay?
Immediately after death and this causes problems in analysing it. However in the most favourable years fragments can survive for 50 000-100 000 years
How did we find out that Neanderthals were not our direct ancestors?
By comparing DNA from a number of neanderthal fossils with DNA from modern humans shows that Neanderthals were not out direct ancestors but that interbreeding between Neanderthals and modern human ancestors did take place
How can scientists analyse DNA from suitable fossils under 100 000 years old?
By using the polymerase chain reaction (which amplifies minute traces of DNA) and DNA profiling
Whatt does lice show about human evolution regarding DNA?
- Modern humans have three types of parasitic lice: head, pubic and body
- head and body lice are related to chimpanzee lice.
- DNA evidence suggests that the common ancestors of humans and chimps diverged about 6 million years ago and the head lice species diverged at the same time
- DNA analysis of the human head and body louse shows that they formed seperate species around 70 000 years ago. Body lice live in close fitting fabric so this suggests when woven clothing became common
- the pubic louse is more closely related to the gorilla louse than to other human lice
- the human and gorilla ancestors diverged about 6 million years ago but the pubic and gorilla lice only diverged about 3 million years ago. This suggests that by then the humans had lost most of their body hair and the texture of the pubic hair was already different from their head hair.
- therefore it can be concluded that the ability to weave clothes was developed long after most of our body hair was lost
Why is it important to look for evidence from traditional studies based on appearance, behaviour or fossil data as well as the evidence from modern DNA and protein studies
Because modern DNA and protein studies relies heavily on how data are interpreted statistics and bioinformatics including computer analysis. It is possible that the same evidence can be interpreted differently
What role does the scientific community play in validating new evidence?
- when a piece of research produces useful results and conclusions it is submitted to a scientific journal. When an article is submitted it goes through a process of peer review dheing which it is read by a number of experts to see if it is reliable
- At scientific conferences scientists working together in the same field get together to discuss new ideas. This helps to promote the development of new techniques in research as well as providing opportunities to challenge the validity of results that are being presented it facilitates the exchange of ideas, data and techniques between scientists from all over the world
What are the key molecules in molecular phylogeny analysis?
Proteins
Does the evidence from biochemical analysis support or conflict relationships based on morphology?
Both
What is gel electrophoresis?
It is a variation of chromatography which can be used to seperate DNA, and RNA fragments, proteins or amino acids according to their size and charge
How is the technique of gel electrophoresis carried out?
- the chemicals to be compared are placed in wells in a gell medium in a buffering solution (to maintain a constant pH) with known DNA or RNA fragments, proteins or amino acids to aid identification
- for identifying DNA the big DNA molecules are cut into fragments by restriction endonucleases (special enzymes that cut DNA into fragments at specific sites)
- the DNA fragments are added to a gel containing a dye which binds to the fragments in the gel and will fluoresce when placed under ultraviolet (UV) light.
- A dye is also added to the DNA samples. This does not bind with the DNA molecules but moves through the gel slightly faster than the DNA so the current can be turned off before all the samples run off the end
- an electric current is run through the apparatus and the DNA fragments move towards the positive anode, because of the negative charge on the phosphate groups of the DNA
- the fragments move at different rates depending on their mass and charge
- once the electrophoresis is complete the plate is placed under UV light. The DNA fluoresces and shows up clearly so the pattern of the different bamds can be identified
- when electrophoresis is used to identify and compare the amino acids in a particular protein, dyes are not added to the gel or the mixture. Ninhydrin is added to the gel after electrophoresis has taken place. It reacts with the amino acids so they show up as purple patches and can be compared with known amino acids for identification
What has biochemistry shown about blood pigments?
- any one group contains only one type of blood pigment
- all vertebrates and many invertebrates have haemoglobin
- all polychaete worms have chlorocruorin
- all molluscs and crustaceans have haemocyanin
What can analysis of amino acids in particular proteins help show?
The relationships within higher groups such as a phylum. For example in mammals, the analysis of fibrinogen reveals how closely the different mammalian groups are related
What are the closest relatives to the hippopotamus based on DNA analysis, proteins analyisis and anatomical observations?
Dolphins and wales
Why did a the theory develop that there are three domains (as opposed to just eukaryotes and bacteria)?
After using the techniques of molecular phylogeny to investigate the theory that chloroplast and mitochondria became part of eukaryotic ancestor cells at the same time as eukaryotes evolved from prokaryotes they discovered the archea was different to the bacteria. They looked at the internal structures of prokaryotes and eukaryotes and compared them to the biochemistry of the proteins involved in their ribosomes and enzymes.
When did the three domains probably have a common ancestor
About 3 billion years ago
What are the two key differences in the three domains?
- archea replicate by binary fission controlled within a cell cycle which seems homogolous tonthe cell cycle in eukaryotic cells but is rather different to bacteria
- the membrane structure and the membrane proteins of archea are unique. They have an ether link in their lipids giving branched molecules that may provide extra strength in extreme environments
How may eukaryotes have evolved from prokaryotes combining the endosymbiotic theory with eukaryotes evolving from prokaryotes?
- An anaerobic ancestral eukaryotic cell engulfs aerobic prokaryote as food
- oxygen levels in atmosphere increase as photosynthetic prokaryotes appear. Oxygen is at best no use to cells, and at worst toxic
- by chance in some cells the aeroibic prokaryote is digested. It uses oxygen for cellular respiration
- aerobic prokaryotes become permanent feature as mitochondria. Copies are made and passed to daughter cells during reproduction.
This is baisically the same for chloroplasts
What are the six kingdoms?
- archaebacteria - prokaryotic cells. These are ancient bacterianwith a wide variety of lifestyles. They include the extremeophiles
- eubacteria (bacteria) - prokaryotic cells. This kingdom includes the true bacteria and the cyanobacteria. They normally reproduce asexually
- protoctista - eukaryotic cells. This kingdom includes all of the single-celled organisms, the green algae, the brown algae and the slime moulds. They mainly reproduce asexually
- fungi - eukaryotic cells. This includes both unicellular organisms such as yeast and multicellular organisms such as toadstools. They are all heterotrophs. They reproduce sexually and asexually
- plantae - eukaryotic cells. The organisms in this kingdom are all multicellular. They are almost all autotrophs and make their own food by photosynthesis. Both asexual and sexual reproduction occurs.
- animalia - eukaryotic ells. The organisms in this kingdom are all multicellular and they are all heterotrophs. They include invertebrates and vertebrates. Sexual reproduction is common but some animals reproduce asexually
In the five kingdom classification system what kingdom were all prokaryotes put in?
The monera
