4.2.2 Classification and Evolution Flashcards
(58 cards)
What is the modern system of classification?
- Doman
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
What is a domain?
- Highest taxonomic rank
- 3 domains = Archaea, Eubacteria, Eukaryote
What is a kingdom?
5 kingdoms = Plantae, Animalia, Fungi, Protoctista, Prokaryote
What is a phylum?
- Groups organisms according to body plan
E.g. Chordata
What is a class?
- Groups organisms to do with general traits
E.g. Mammalia
What is an order?
- Groups organisms according to organisms nature
E.g. Carnivora
What is a family?
- Groups of similar genera, based on reproductive characteristics
What is a genus?
Groups of similar species
What is a species?
A group of organisms that can interbreed to produce fertile offpsring
What is the binomial naming system?
- Genus then species
- Given two Latin names
- Universal across all countries and languages
What are the features of the Animalia kingdom?
- Eukaryotic
- No cell wall
- Multicellular
- A nucleus and other membrane bound organelles
- Heterotrophic (large organic molecules digested into smaller ones for absorption)
- Food store as glycogen
E.g. birds, mammals, jellyfish
What are the features of the Plantae kingdom?
- Eukaryotic
- Multicellular
- Cellulose cell wall
- Autotrophic (use light to produce food by photosynthesis)
- Store food as starch
E.g. algae, ferns, conifers
What are the features of the Fungi kingdom?
- Eukaryotic
- Chitin cell wall
- Usually multicellular or have mycelium (but can be unicellular)
- No chloroplasts
- Saprophytic feeders
- Store food as glycogen
E.g. yeast, moulds
What are the features of the Prokaryotae kingdom?
- Prokaryotic
- Unicellular
- Cells have no nucleus (circular DNA)
- Absorb nutrients or produce internally by photosynthesis
E.g. bacteria
What are the features of the Protoctista kingdom?
- Eukaryotic
- Single cell organisms or a colony of single cells
- Some have chloroplasts
- Move using cilia/flagella/amoeboid mechanisms
- Autotrophs, heterotrophs or both
E.g. amoeba, plasmodium, protozoa
What is artificial classification?
- Based on observed characteristics
- Organisms adapt to their environment so often look similar if they live in a similar environment (convergent evolution)
What is natural classification?
- Includes natural relationships, internal and external factors
- Based on evolutionary relationships
- Evidence used from DNA and amino acid sequences
How are DNA sequences used for natural classification?
- Changes in DNA are caused by mutations
- More differences = less closely related species as have evolved separately for longer periods of time
- Similar DNA sequences = closely related
What is DNA hybridisation?
- DNA from 2 species is extracted, purified and cut into small pieces
- DNA is heated to about 90°C to break the H bonds between the 2 strands
- On cooling, the strands combine with others that have a complementary base sequence
- To separate the strands again, they are heated
- The more similar, the more H bonds form so will take a higher temperature to separate
How are amino acid sequences used for natural classification?
E.g. cytochrome C (protein used for respiration)
- Not identical in all species
- Compare the sequences of amino acids in the Cytochrome C protein to find how closely related organism are
- Similar sequence = closely related
- More differences = less closely related species
How does immunological comparison work?
- Serum albumin from Sp. A injected into Sp. B
- Sp. B produces antibodies specific to the antigen sites on Sp. A albumin
- Serum is extracted from Sp. B; containing antibodies specific to antigens on Sp. A’s albumin
- Serum from Sp. B is mixed with blood from Sp. C
- Antibodies respond to the antigens on the albumin of Sp. C -> response is the formation of a precipitate
- More similar antigens = more precipitate formed and more closely related the species
Why was domain introduced as a new taxonomic rank?
- Extremophiles were discovered
- Classified as Archaea
What are the features of the Bacteria domain?
- Prokaryotic
- Circular DNA
- No membrane bound organelles
- 70s ribosomes
- No introns
- 5 proteins in RNA polymerase
- Can’t grow in extreme temperatures (100°C)
- Peptidoglycan cell wall
- No cytoskeleton
- Not poisoned by diptheria toxin
- Sensitive to streptomycin (antibiotic)
What are the features of the Archaea domain?
- Prokaryotic
- Circular DNA
- No membrane bound organelles
- 70s ribosomes
- Some introns
- 8-10 proteins in RNA polymerase
- Extremophiles can grow in extreme temperatures (100°C)
- No peptidoglycan cell wall
- No cytoskeleton
- Can be poisoned by diptheria toxin
- Not sensitive to streptomycin