Species & Taxonomy

• COURTSHIP BEHAVIOUR:

  • MATING: Organisms within the same species can mate to produce fertile offspring. Organisms only breed with the same species so they can pass their genes to their offspring
• COURTSHIP BEHAVIOUR:

  • IDENTIFYING MATES: Potential mates of the same species can be identified through physical features, biochemical features, and courtship behaviours. Courtship behaviours= complex displays that help an individual attract a mate (eg dancing of some male birds). It can influence chances of survival of the individual and the survival of the species
• COURTSHIP BEHAVIOUR:

  • SPECIES SPECIFIC: Courtship behaviours are species specific. Individuals of the same species will do the same courtship behaviours and only individuals of the same species will respond to the courtship behaviour (so can be used for classifying species)
• COURTSHIP BEHAVIOUR:

  • EG PEACOCKS: Have patterns on their tails which they display to females (peahens) to attract a mate. Only male peacocks have this tail pattern, & only female peahens will respond to this pattern
• COURTSHIP BEHAVIOUR: Recognise members of their species

  • To ensure mating only takes place between members of the same species as only members of the same species can produce fertile offspring
• COURTSHIP BEHAVIOUR: Identify a mate capable of breeding


  • Both partners need to be sexually mature, fertile, & receptive to mating
  • Females are receptive for a short period around the time they produce eggs, courtship behaviour can identify females at this receptive stage
  • If she does not respond/ different pattern of behaviour -> male turns his attention elsewhere
• COURTSHIP BEHAVIOUR: Form a pair bond


  • That will lead to successful mating & raising of offspring
• COURTSHIP BEHAVIOUR: Synchronise mating


  • So it takes place when there is a maximum probability of sperm and egg meeting
• COURTSHIP BEHAVIOUR: Become able to breed


  • By bringing a member of the opposite sex into a physiological state that allows breeding to occur
• CLASSIFICATION (grouping of organisms):

  • TAXONOMY: The theory & practice of biological classification
• CLASSIFICATION (grouping of organisms):#

  • ARTIFICIAL CLASSIFICATION; Divides organisms according to differences, have the same function but not the same evolutionary origins (eg butterflies & birds have wings for flight, but originated in different ways)
• CLASSIFICATION (grouping of organisms):

  • TAXA: Closely related organisms are grouped together into taxa (singular=taxon). The phylogeny of organisms (their evolutionary relationships) is important for determining which taxa an organism is part of
• CLASSIFICATION (grouping of organisms):

  • HIERARCHY: Each taxon is arranged into a hierarchy which divides into smaller, more specific taxa at each level. There is no overlap between taxa at the same level
  • STAGES: Domain (Bacteria, Archaea, Eukarya), Kingdom, Phylum, Class, Order, family, Genus, Species
  • BINOMIAL NAMES: The binomial system= the naming system used in classification. It consists of the genus (generic name) and the species (specific name) of the organism. The names are always written italics or underlined if handwritten. The genus is always capitalised
• PHYLOGENY:

  SHARED ANCESTRY: Phylogeny= the evolutionary relationship of an organism/ group of organisms. Phylogenies are based on the fact that all organisms share a common ancestor and more closely related organisms will share a more recent common ancestor than more distantly related organisms. Classifies species into groups based on homologous characteristics derived from their ancestors in a hierarchy
• PHYLOGENY:

  PHYLOGENETIC TREE: Shows the evolutionary relationship between different species and their most recent common ancestor. Each branch shows a different species. The point that 2 branches join is the common ancestor of the 2 species
• DOMAIN DIFFERENCES

  • BACTERIA: are a group of single -celled prokaryotes with the following features: the absence of membrane -bounded organelles such as nuclei or mitochondria , unicellular, although cells may occur in chains or clusters, ribosomes are smaller (70S) than in eukaryotic cells, cell walls are present and made of murein (but never chitin or cellulose), single loop of DNA made up of nucleic acids but no histones
• DOMAIN DIFFERENCES

  • ARCHAEA: are a group of single -celled prokaryotes that were originally classified as bacteria which they resemble in appearance. They differ from bacteria because: their genes and protein synthesis are more similar to eukaryotes, their membranes contain fatty acid chains attached to glycerol by ester linkages, there is no murein in their cell walls, they have a more complex form of RNA polymerase.
• DOMAIN DIFFERENCES

  EUKARYA: are a group of organisms made up of one or more eukaryotic cells. Their features are: their cells possess membrane -bounded organelles such as mitochondria and chloroplasts, they have membranes containing fatty acid chains attached to glycerol by ester linkages, not all have cells with a cell wall, where they do it contains no murein, ribosomes are larger (80S) than in Bacteria and Archaea
• PROBLEMS WITH DEFINING SPECIES:

  • EVOLUTION: Species can change & evolve over time, some individuals may develop into new species
• PROBLEMS WITH DEFINING SPECIES:

  • VARIATION: Within a species there is variation among individuals
• PROBLEMS WITH DEFINING SPECIES:

  • EXTINCT: Many species are extinct with no fossil record
• PROBLEMS WITH DEFINING SPECIES:

  • SEXUAL REPRODUCTION: Some species rarely reproduce sexually
• PROBLEMS WITH DEFINING SPECIES:

  • ISOLATED INDIVIDUALS: Members of different populations of the same species may be isolated then never interbreed & then classified as a different species, but then are discovered to be the same species when their ability to interbreed is tested
• PROBLEMS WITH DEFINING SPECIES:

  • HYBRID/ STERILE ORGANISMS: Some types of organisms are sterile/ infertile (eg some crops produced have no seeds)
• PROBLEMS WITH DEFINING SPECIES:

  • Evolution
  • Variation
  • Extinction
  • Sexual reproduction
  • Isolated individuals
  • Hybrid/ sterile organisms
• EVOLUTIONARY RELATIONSHIPS:

  • ANTIBODY-ANTIGEN INTERACTIONS: Species produce specific antibodies that recognise foreign proteins. An organism's antibodies can be isolated & mixed with another organism’s proteins to see how many antigen antibody complexes are formed. More complexes formed= more closely related the 2 organisms are
• EVOLUTIONARY RELATIONSHIPS:

  • GENOME SEQUENCING: The base sequence of organisms can be sequencing & compared to other organisms. The more similar the base sequences are= the more closely related the 2 organisms are. It helps clarify evolutionary relationships
• EVOLUTIONARY RELATIONSHIPS:

  • AMINO ACID SEQUENCING: The amino acids that make up proteins in an organism can be sequenced and compared to other organisms. The more similar the amino acid sequences are= the more closely related the 2 organisms are
• IMMUNOLOGICAL COMPARISONS OF PROTEINS:

  • HOW: Antibodies of one species will respond to specific antigens on proteins in the blood serum of another
• DNA TECHNOLOGY: IMMUNOLOGICAL COMPARISONS OF PROTEINS

  
• Immunological comparisons of proteins

  1. Serum from species A is injected into species B

  2. Species B produces antibodies specific to antigen from species A

  3. Serum is extracted from species B; this serum contains antibodies specific to the antigens from species A

  4. Serum from species B is mixed with serum from the blood of a third species C

  5. The antibodies respond to their corresponding antigens in the serum of species C
• Precipitate formation

  The response when antibodies and their corresponding antigens interact
• Higher the number of similar antigens

  More precipitate is formed and the more closely the species are related
• Fewer the number of similar antigens

  Less precipitate is formed and the more distantly the species are related
• IMMUNOLOGICAL COMPARISONS OF PROTEINS: