Unit 2.1

• Classification is the act of grouping things based on certain conditions
• Phylogenetic is a term which reflects evolutionary relatedness
• A phylogenetic tree is a diagram that shows the evolutionary relationship between organisms.
• The three domains of life are Archaea, Bacteria, Eukaryota
• A taxon is any group within a system of classification.
• The hierarchy os biological classification is: kingdom, phylum, class, order, family, genus, species.
• A classification system allows us to infer evolutionary relationships. Is organisms are in the same taxon, they must be closely related.
• A domain is the largest taxon and all living things belong to one of the three domains: eubacteria, archaea and eukaryotic.
• The 5 kingdoms are prokaryotic, protoctista, animalia, plantae and fungi.
• Prokaryotic are microscopic. This kingdom contains all the bacteria, archaea and cyanobacteria
• The kingdom protoctista contain protoctists. Some are unicellular and are the major component of plankton. Others are colonial.
• Divergent evolution refers to the development of different structures over long periods of time, from the equivalent structures in related organisms.
• Convergent evolution refers to the development of similar features in unrelated organisms over long periods of time, related to natural selection of similar features in a common environment.
• Analogous structures have a corresponding function and similar shape, but have a different developmental origin.
• There are 4 pieces of genetic evidence used to assesses relatedness: DNA sequences, DNA hybridisation, Amino acid sequences and immunology.
• During the course of evolution, species will undergo changes in their DNA base sequence. These changes accumilate until organims are so different that they are considered different species. DNA analysis can be used to compare DNA sequences and therefore show evolutionary relationships.
• Proteins of different species can be compared using immunological techniques. If you mix the antigens of one species with specific antibodies of another, the antibodies and antigens coagulation. The closer the evolutionary relationship, the more coagulation occurs.
• DNA hybridisation involves comparing the DNA base sequences of 2 species. The DNA is extracted, separated into single strands and cut into fragments. The fragments of the 2 species are mixed, and where they have complimentary base pairs, they hybridise together. The more they hybrdise, the more DNA the species have in common, and so the more closely related they are.
• The sequence of amino acids in proteins is determined by the DNA base sequence. The degree in similarity between the amino acid sequences of the same protein in 2 species will reflect how closely related the 2 are.
• a species is a group of organisms which are able to reproduce successfully and have fertile offspring.
• Autotrophs are organisms which produce energy for themselves (for example plants carry out photosynthesis)
• Heterotrophs require external energy sources (for example food, water)
• The kingdom fungi contains uni/multicellular organisms with chitin cell walls. They are heterotrophic and reproduxe via spores. Unicellular yeast, moulds and mushrooms are examples of fungi.
• The plantae kingdom are multicellular organisms with cellulose cell walss. They are autotrophic and reproduce via spores or seeds.
• The protoctista kingdom has unicellular organisms which may be heterotrophic, automorphism or both. It is a very diverse kingdom.
• Extremeophiles live in extreme conditions. For example, thermophiles live in high temperatures, and halophiles live in high saline content.
• The animalia kingdom contains multicellular organisms with no cell walls. They are heterotrophic, and have nervous coordination.
• The prokaryotae kingdom contains unicellular prokaryotes. They have no membrane bound organelles or a nucleus, and can be heterotrophic or autotrophic.
• Evidence for the 3 domains comes from rRNA studies.
• There are 3 different adaptions: anatomical (changes in appearance), behavioural (changes in behaviour) and physiological.
• Genetic biodiversity is measured by taking DNA from individuals of a population and determining the DNA sequences.
• Gel electrophoresis can be used to produce genetic fingerprints. Fragments of DNA and proteins are separated via the gel, which allows small fragments to move further. The electrical charge causes the negatively charged DNA to move to the positive electrodes. A banding pattern is produced.
• Individuals with more variation in their banding patterns have a higher genetic biodiversity.
• Genetic biodiversity can be assessed by determining the number of alleles (different forms of a gene) at different loci (position of genes on a chromosome)
• Analysis of nucleotide sequences in DNA reveals similarities and differences on the base sequence. The more variation in the sequences, the higher the biodiversity in species.
• Genetic polymorphism is assessed by determining the number of alleles at 1 gene locus, and the proportion of the population that has a particular allele.
• The phylum is based on the body plan of the organism.
• Saprophytes are plants, fungi or microorganisms which live on dead or decaying organic matter.
• Biodiversity varies spatially. It increases from the poles to the equator. This is due to a variety of reasons.
• Biodiversity increases towards equator because:

  • More UV light causes a higher mutation rate and as a result, rapid evolution.
  • More species types means more habitats and niches (food types).
  • More stable temperature range and water availability result in more favourable conditions for survival.
  • More species leads to more competition leading to specialised and narrower exploitation of niches, so it is more difficult to move out of the area.