Topic 3.1 Classification Flashcards
Define classification
The process of naming and organising organisms into groups based on their charecterisitics
Name the eight groups in the classification from largest to smallest
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Define species
Reproductive species
A group of organisms that can interbreed to produce fertile offspring
Give a limitation of this definition of species
Doesn’t account for species that reproduce asexually
What is morphological species?
If two organisms look similar they are likely to be a single species
This doesn’t work as organisms such as the peacock and pea hen can interbreed but don’t look similar
Why can it be hard to assign organisms to one species?
- Species can often change both morphologically and genetically over time
- How ‘similar’ do two organsims need to be to be classed as the same species?
- Hybrids: classed as new species or not?
How can we analyse evolutionary relationships genetically?
- Gel electrophoresis
- DNA sequencing
- Bioinformatics
How does gel electrophoresis work?
Fluorescent DNA fragments are placed at one end of an agar plate. An electric currrent is applied, causeing DNA fragments to move towards the positively charged end. The resulting pattern of bands represents amino acids and is unique to every individual
How does DNA sequencing work?
DNA is broken into small fragments, terminated at different lengths by fluorescently marked nucleotides, then duplicated using PCR. The fragments undergo gel electrophoresis, with the smallest fragments travelling furthest, meaning we can read the base sequence of the fragment according to the distance travelled.
What is bioinformatics?
The use of technology and software to analyse large amounts of biological data. Can compare entire genomes and look for where mutations have caused divergence in the phylogenetic tree
How does the scientific community evaluate data?
Papers sent out to other experts for peer review to check for validity. If data and conclusion seem reasonable, results are published in scientific journals. May also be presented at conferences.
Why has the five-kingdom model of classification come under scrutiny?
Relies heavily on physical observations. Since the introduction of DNA sequencing, new models have been developed.
Why is the three-domain model of classification more accepted by the scientific community?
Takes into account research of a particular ribosomeal unit. More accurately represents evolutionary relationships than five-kingdom.
