BIOL1003 Study Guide - Quiz Guide: Mendelian Inheritance, Zygote, Anemia
BIOL1003 Evolution
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
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BIOL1003 Evolution
• 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
• The fact that life on earth has evolved (phenotypes changed) prompted the
greatest scientific revolution ever- had consequences on the way humans view
themselves
• Charles Darwin- Natural Selection- why evolution is inevitable given a few basic
conditions
• Need an evidence-based argument for the occurrence of evolution
• Rules for writing Linnaean names
oGeneric names always begin with a capital letter and are types in italics or
are underlines. The names of other taxomic levels are neither italicised
nor underlined
oSpecies names consist of two words- the first is the generic name and the
second Is the specific epithet, written in italics or underlined
oIf a species is referred to repeatedly, the first reference is written in full,
and later references can be abbreviates to the initial of the generic name
followed by the specific epithet in full
• The description and enumeration of species is called taxonomy, the study of their
relationships is called systematics, and a depiction of relationships is called a
phylogeny
• Doman, Kingdom, Phylum, Class, Order, Family, Genus, Species
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BIOL1003 Evolution
Natural Selection
• Each generation of organisms that have a favourable trait will have a
reproductive advantage, and if that trait is heritable then the frequency of the
trait will increase in population
• The interaction between genes and the environment determines what the
individual ends up looking like and acting like (phenotype)
• Genes are far more stably inherited than the parental environment- DNA is
copied with greater fidelity
• When we talk about evolution of a trait- we assume this means that some genes
have become more common in the population, while their 'rivals' for the same
'position' on a chromosome (locus) have become rarer
• Alleles- different version of a gene
• The genes persist is they are good at getting themselves copied into the next
generation as they code for traits that produce phenotypes that are god at
breeding successfully
• Won't end up with only one type of gene (allele) due to new types of genes
arising through mutations (copying errors in genes, slightly different protein,
phenotypic change)
• Adaptations- traits that look designed and have evolved due to natural selection
• All complex functional traits only come to existence through natural selection
• Differential replication- only the variants that persist are those that are good at
making copies of themselves (producing offspring)
• Tautology or lack of testability
oNatural selection is sometimes incorrectly described as survival of the
fittest, and the fittest are those who survive
oPeople have criticised Darwin's hypothesis as a tautology and therefore
untestable
oTautology- Using words to repeat yourself within a sentence
oIf the first thing you say is not an explanation, then neither is the second
oCritical testing of hypotheses is fundamental to the scientific method
oDarwin's principle of natural selection can be stated without tautology
and can be tested empirically and rejected- in some cases it will be
rejected because the study system does not fulfil the assumptions
oSyllogism- a line of argument where provided that a set of premises is
true, consequences must follow- does not suffer from tautology and is
easily testable
• Types of mutations
oSomatic mutations: affect cells in the organism, not heritable
oGerm-line mutations: affect gametes, heritable
• Claims about the world that have to be true for evolution by natural selection to
occur
oVariation among individuals in some attribute or trait
oA consistent association between that trait and some measure of
reproductive success (fitness correlation)
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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.
