BIOL1003 Lecture Notes - Lecture 6: Methionine, Peptidoglycan, Eukaryote
Evolution
• Biologists make observations, acquire a set of concepts, a theory, that they can
then test and apply to new situations that help them explain what they see
• Charles Darwin
oDemonstrates that unity and diversity are the product of evolution
Provided the evidence for evolution
oProposed a hypothesis for how adaption comes about- natural selection
Simple idea with profound consequences
• Unity
oDespite great differences in form, organisms show extraordinary
similarity in their underlying structures and the mechanisms that allow
them to exist
oE.g. bones in mammal neck, male and female gametes, DNA, ATP
• Adaption
oDespite the limited set of building blocks, organism still show exquisite fit
to the environments in which they live
oThe environment poses 'problems' which have been 'solved' by different
species in different ways
oDifferent neighbours, species, organisms surrounding them also changes
oAdaptations- many aspects of plants and animals which look as though
they were designed for the environment
oE.g. camouflage, mimicking, toleration of extreme temperatures, ability
to break down toxic chemicals, sight
• Diversity
oDespite the unity in the processes of life, organisms show bewildering
diversity in both their physical appearance, and in the varieties of
organisms that share similar forms (different taxa)
• The basic unit of diversity is the species, which the biological species concept
defines as a population whose members have the potential to interbreed
naturally to form viable, fertile offspring, but cannot do so with members of
other populations
Characteristic Bacteria Archaea Eukarya
Chromosomes Circular Circular Linear
Nucleus Absent Absent Present
Organelles Absent Absent Present
Histones Absent Present Present
RNA polymerase One kind Several kinds Several kinds
Peptidoglycan in
cell wall
Present Absent Absent
Amino acid that
initiates protein
synthesis
Formuymethionine Methionine Methionine
• Different traits suggest different ways to divide up species into taxa, so our
classification depends on which traits we use to divide up species into different
groups
• Need a way of describing the world that is objective
find more resources at oneclass.com
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Document Summary
Provided the evidence for evolution: proposed a hypothesis for how adaption comes about- natural selection. The basic unit of diversity is the species, which the biological species concept defines as a population whose members have the potential to interbreed naturally to form viable, fertile offspring, but cannot do so with members of other populations. Methionine: different traits suggest different ways to divide up species into taxa, so our classification depends on which traits we use to divide up species into different groups, need a way of describing the world that is objective. Early philosophers believed that the world consisted of fundamental ideals or essences, that variation was deviation within a type- imperfections from the master plan. In the early 1800s it was clear this was wrong, there was abundant evidence that species composition had changed radically over the history of life on earth.
