Classification

what is classification?

putting things into groups

what is biological classification?

identifying and sorting living organisms into groups

what is taxonomy?

• the study of principles behind classification (the study of differences between the groups

• e.g. grouping organisms into a hierarchy of taxa

what is a taxa?

a hierarchal group discussed in classification

what is phylogeny?

the study of evolutionary relationships

what is taxonomy the system of?

grouping, ordering and categorising things - the science of classification

why do we do taxonomy?

to better understand evolution we need to be able to find links and relationships between living things and taxonomy enables this

why is it important to classify organisms?

• to identify species

• to predict characteristics

• to discover evolutionary links

• allows scientists to share their research worldwide as it is a single classification system

• links between organisms can be seen round the world

what did Carl Linnaeus do?

• came up with the system of classification

• devised the binomial system of naming living organisms (binomial nomenclature)

• used Latin as a universal language

how does the binomial system work?

Uses 2 names:

1. Genus

2. species

• always in this order e.g. Homo sapiens or Homo sapiens

• Genus always has a capital letter and is always written first

• species has a lower class letter and is written second

• the names are always italicised or underlined

what problems may have occurred before using Linnaeus when a common name was used?

• different common names in different countries or part of the country

• translation may be given different names

• same common name may be used for different species in different parts of the world

what is a species?

• basic unit of classification

• species are very similar in appearance, anatomy, physiology, biochemistry and genetics

what is the biological definition of a species?

a group of individuals that are similar in appearance, anatomy and physiology, biochemistry and genetics and that can interbreed to produce fertile offspring

what may the problems with the definition of a species?

• organisms may be extinct

• organisms reproduce asexually

• members of the same species can look very different to each other

• not possible to study whether 2 organisms reproduce successfully together (practical and ethical issues)

• what happens at the point when one organism is about to evolve into another

what are the 8 taxonomic groups in descending hierarchal order?

• domain

• kingdom

• phylum

• class

• order

• family

• genus

• species

what is can be used to help remember the 8 taxonomical groups in descending hierarchal order?

• Don’t

• Kick

• Poppy

• Cuz

• Otherwise

• Flavia

• Gets

• Stroppy

what is phylogenetics?

the study of how closely species are related - the evolutionary relationships between organisms

what does phylogenetics do and what does it show?

uses the sequence of bases in DNA of different species and puts them in a phylogenetic tree

which organisms will have the greatest number of similarities and smallest amount of differences?

organisms in the smallest group (species)

organisms in which taxonomic groups contain the greatest number of differences and fewest similarities?

larger taxonomic groups (genus or phylum)

what does DNA sequencing show?

• The more similar the sequence between 2 species, the more closely related they are, the more recent their common ancestor

• The greater the difference in their DNA sequences, the greater the evolutionary distance between the 2 species, the less recent the common ancestor

• if the DNA is very similar, then the 2 organisms are probably the same species

what does the % divergence in DNA sequencing show?

the greater the % divergence (the number of bases that are different/total number of bases), the less recent the

how can we use phylogeny by comparing proteins?

• we can work out how related different species are by comparing the amino acid sequence in proteins as well as DNA

• by sequencing the same protein from 2 species and looking at the amino acid sequence

• the greater the difference in the amino acid sequence, the greater the divergence in the evolutionary relationship between 2 species and the less recent the common ancestor is

what are some proteins that all organs that respire have and so can be used for protein sequencing?

• Cytochrome C

• haemoglobin