Topic 3.1 Classification Flashcards
Define classification
The process of naming and organising organisms into groups based on their characteristics
Name the 8 groups in the classification hierarchy, from largest to smallest
- domain
- kingdom
- phylum
- class
- order
- family
- genus
- species
Define species
a group of organisms that can interbreed to form fertile offspring
Give a limitation of the reproductive species model
Doesn’t account for species that reproduce asexually
Why can it be difficult to assign organisms to one species?
- species often change both morphologically and genetically overtime
- how ‘similar’ do two organisms need to be to be classed as the same species
- hybrids- classed as new species or not
How can we analyse evolutionary relationships genetically?
- DNA sequences
- Gel electrophoresis
- Bioinformatics
How does gel electrophoresis work?
- agar gel in a tray with wells where the DNA fragments go
- apply an electrical current
- the fluorescent DNA fragments are slightly negatively charged
- move towards the anode and the smaller fragments travel further
- creates a DNA profile with bands of amino acids
How does DNA sequencing work?
- DNA broken into small fragments
- terminated at different lengths using fluorescently marked nucleotides, then duplicated using PCR
- fragments undergo gel electrophoresis, with the smallest fragments travelling further
- can read the base sequence of the fragment according to distance travelled
What is bioinformatics?
the use of technology and software to analyse large amount 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 expert 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 5 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 3 domain model of classification more accepted by the scientific community?
takes into account research of a particular ribosomal unit and more accurately represents evolutionary relationships than 5 kingdom
What is taxonomy?
the science of describing, classifying and naming living organisms
Define evolution
the process by which natural selection acts on variation to bring about adaptations and eventually speciation
Define biodiversity
biodiversity is a measure of the variety of living organisms and their genetic differences
What are domains?
the 3 largest classification groups, including Eukaryota, Bacteria and Archaea
What kingdom does Archaea contain?
one kingdom: archaebacteria
What kingdom does the bacteria domain contain?
Eubacteria
What are the 4 eukaryotic kingdoms?
protoctista, fungi, plantae, animalia
Describe archaebacteria
ancient bacteria, thought to be found only in extreme conditions but now found in more places e.g. soil
Describe eubacteria
‘true bacteria’ for example bacteria that causes disease and are useful in our digestive system
Describe the 4 eukaryotic families (protoctista, fungi, plantae, animalia)
protoctista- microscopic, some are heterotrophs (have to eat other organisms) and some autotrophs (make their own food by photosynthesis) e.g. amoeda, chlamydomonas
fungi- all heterotrophs, most are saprophytic and some parasitic, they have chitin, not cellulose in their cell walls
plantae- basically all autotrophs
animalia- all heterotrophs that move their whole bodies around during at least one stage of their lifecycles. including invertebrates and vertebrates
What is morphology?
the study of form and structure of organisms
What are analogous features?
features that look similar or have a similar function but are not from the same biological origin
What are homologous features?
structures that genuinely show common ancestry
What is a genus?
a group of species that all share common characteristics
What is the ecological species model?
based on the ecological niche occupied by an organism, not robust because niche definitions vary and an organism can occupy multiple niches
Define the mate-recognition species model
based on unique fertilisation systems, including mating behaviour, although many species mate or cross pollinate with other species
What is the genetic species model?
based on DNA evidence
Define the evolutionary species model
based on shared evolution relationships between groups of organisms
Name the limitations of species models
- finding evidence
- interbreeding to form fertile hybrids
- many organism don’t reproduce sexually
- fossil organisms can’t reproduce
What is the morphological species model?
based solely on the appearance of the organisms observed
Define sexual dimorphism
where there is a great deal of difference between the appearance of the male and female of a species
What is molecular phylogeny?
the analysis of the genetic material of organisms to establish their evolutionary relationships
Define DNA sequencing
the process by which the base sequences of all or part of the genome of an organism is worked out
What is DNA profiling?
the process by which the non-coding areas of DNA are analysed to identify patterns
What is bioinformatics
the development of software and computing tools needed to organise and analyse raw biological data
What is an endosymbiont?
an organism that lives inside the cells or the body of another organism
What is the monera?
a kingdom in the five-kingdom classification system that contains the archaea and eubacteria
What is the protoctista?
a kingdom that contains all single-celled organisms
Define extremophiles
bacteria that can survive extreme conditions of heat, cold, pH, salinity and pressure
What are heterotrophs?
organisms that cannot make their own food
What are autotrophs?
organisms that can make their own food, either by photosynthesis or chemosynthesis
Define electrophoresis
a method of separating fragments of proteins or nucleic based on their electrical charge and size
