Classification And Evolution 4.3 Flashcards
What is the binomial system?
-a system that uses the genus name and the species name to avoid confusion when naming organisms
What is classification?
-the process of placing living things into groups
What are the eight taxonomic levels in the current system of classification?
-Domain-> highest taxonomic rank. There are 3 domains
-Kingdom-> they are 5 main kingdoms.
-Phylum-> a major subdivision of the kingdom. A phylum contains all the groups of organisms that all have the same body plan e.g. possession of a backbone.
-Class-> a group of organisms that all possess the same general traits e.g. same number of legs
-Order-> a subdivision of class using additional information about the organism
-Family-> a group of closely related genera
-Genus-> a group of closely related species
-Species-> the basic unit of classification. All members of a species show some variations, but all are essentially the same
What is a hierarchy ?
-smaller groups arranged within larger groups
-no overlap between groups
-classification systems are an example of a hierarchy
How do you write a binomial name?
-write the genus name and, giving an upper case to the first letter
-then write the species name all in lowercase
-if written in printed text it should be in italics, if handwritten it is underlined
What is the advantage of the binomial naming system?
-provides a universal name for the organism
-every scientist in every country will use the same name
-this avoids potential confusing caused by using common names
What are the five kingdoms?
-Prokaryotae
-Protoctista
-Fungi
-Plantae
-Animalia
What are some features of the Prokaryotae kingdom ?
-have no nucleus
-have a loop of DNA that is not arranged in linear chromosomes
-have naked DNA (DNA that is not associated with histone proteins)
-have no membrane-bound organelles
-have smaller ribosomes than in other groups
-have cells smaller than those of eukaryotes
-may be free-living or parasitic (some cause diseases)
What are some features of the Protoctista kingdom?
-are eukaryotic
-are mostly unicellular (but many algae are multicellular)
-show a wide variety of forms (the only thing that all Protoctists have in common is that they do not qualify to belong to any of the other four kingdoms)
-show various plant-like or animal-like features
-are mostly free-living
-have autotrophic or heterotrophic nutrition- some photosynthesise, some ingest prey, some feed using extra cellular enzymes and some are parasites
What are some features of the Fungi kingdom?
-are eukaryotic
-can exist as single cells (called yeasts) or they have a mycelium that consists of hyphae
-have walls made of chitin
-have cytoplasm that is multinucleate
-are mostly free-living and saprophytic- this means that they cause decay of organic matter
What are some features of the Plantae kingdom?
-are eukaryotic
-are multicellular
-have cells surrounded by a cellulose cell wall
-are autotrophic (absorb simple molecules and build them into larger organic molecules)
-contain chlorophyll
What are some features of the Animalia kingdom?
-are eukaryotic-have nucleus and membrane bound cells
-are multicellular
-heterotrophic (digest large organic molecules to form smaller molecules for absorption )
-are usually able to move around
When scientists first began classifying organisms they relied solely on ….
Observable features
How is cytochrome c used as evidence in classification?
-cytochrome c is a protein used in the process of respiration, all living organisms that respire have cytochrome c , but cytochrome c is not identical in every species.
-the amino acids in cytochrome c can be identified, if we compare the sequence of amino acids in the samples of cytochrome c from two different species , we can then draw conclusions:
-> if the sequences are the same, the two species must be closely related
-> if the sequences are different, the two species are not so closely related
-> the more differences found between the sequences, the less closely related the two species
How is DNA is used as evidence in classification ?
-found in all living organisms
-DNA provides the genetic code, the code is universal (it is the same in all organisms) Meaning a particular sequence of DNA codes for the same sequence of amino acids acids in a bacterium as in any other organism
-mutations occur at random
-comparisons of DNA sequences provide another way to classify species, the more similar the sequence in a part of the DNA, the more closely related the 2 species
-if there are many differences, the species have evolved separately for a long time and they can be considered as less closely related
-this is probably the most accurate way to demonstrate how closely related one species is to another
What is the three domain classification system?
-suggested by Carl Woese
-he based his ideas on detailed study of the ribosomal RNA gene
-the three domains consist of :
.Bacteria (eubacteria)- found everywhere and most bacteria within this kingdom
.Archaea (archaebacteria)- live in extreme environments
.Eukaryota
-organisms are split into these 3 domains based on the type of rRNA and ribosomes they have and the cell membrane structures
Describe the domain Bacteria
Prokaryotic cells
Distinct cell membrane lipids.
Have peptidogylcan (murein) in their cell walls.
Unique RNA polymerase enzyme.
Divide by binary fission
Describe the domain Archaea
typically found in extreme environments.
Prokaryotic organisms.
Have histones so gene and protein synthesis is more similar to Eukarya than Bacteria.
No peptidogylcan in their cell walls.
Different cell membranes that contain fatty acids bound to glycerol by ether linkages.
Have a more complex form of RNA polymerase than Bacteria.
Describe domain Eukarya
All have nuclei and membrane-bound organelles.(eukaryotic )
Divide by mitosis
Can produce asexually or sexually
What is phylogeny?
-the study of the evolutionary relationships between organisms
Summarise Darwin’s conclusions
-there is a struggle to survive
-better adapted individuals survive and pass on their characteristics
-over time, a number of changes may give rise to a new species
What is the difference between classification and phylogeny?
Classification is simply sorting organisms into groups. Phylogeny investigates the evolutionary relationships between organisms.
How did Darwin and Wallace contribute to the theory of evolution?
-Darwin observed many different types of finch on the Galapagos Islands but he believed they must be related due to many similarities. He concluded a bird born with a beak more suited to the food available would be more likely to survive than one whose beak was less well suited. Those that survive pass the trait on to their offspring.
-Wallace had many similar ideas so they published their theory together
-Darwin then published his book ‘The Origin of Species’
What is the evidence for evolution ?
-fossils-> looking at the remains of extinct organisms and comparing to those alive today. Dating the rocks can give a timeline to the changes seen
-comparing biological molecules
-DNA-> looking at the similarities and differences between DNA sequences in different organisms
