Edexcel A level Biology B Student Book 2 ActiveBook
I remember writing these notes in Y12, I know first hand the amount of time that has to be invested into this subject and how difficult it can be to identify the key information. These notes are time savers, giving you more time to practice questions and past papers. The notes used for all my A-lev...
Gene and allele frequency
Biodiversity is notonlyabout the number ofdifferentspecies and howthey are distributed
Mutations arechangesin the DNAstructure Many mutations have no eeeect on the phenotyp
but other may have lethal or severeeffects
mutations can increasethegenepool oe a populationbyincreasing the number of dice rent allele
available
The relativefrequency oe an allele is known as the allele frequency lemutationsresultin
advantageousfeatures the frequency or that allele willincrease le itresults in a
disadvantageous
feature the alleleerequencywill be retained at a verylowfrequency or removed
completely from thegenepool
Changesin allelefrequency dueto natural selection lead to theevolutionoe a new species
Measuringgeneticbiodiversity
Genetivarietywithin a speciesis
veryimportantwithoutthis
variety
the populationisvery
vulnerable
A crearmodeloegeneticdiversity
within a population can be
byanalysed
the compassionoeDNA
regions to find similaritiesand
diceerences
Models of the molecular phylogeneticrelationships between related organisms based on DNAano
otherevidencehave proven to beveryuseful tool for measuringbiodiversity
Biodiversity maps allowscientists to highlightareas thatneedprotection and with regular
updating provides away oe monitoringchanges in biodiversityanywhere
he isolatedislandsof Hawaii
All insectspeciesin Hawaiiseemed to have developed ero m only400species
Inisolatedcircumstances a smallgroupoe sounderorganisms have adapted and evolvedto
fill different niches
Places where endemism is common often have rich biodiversity in terms ofspeciesnumbers
butrelatively low geneticdiversity
Reasonwhyendemic areas are very vulnerable to disease introduction
, Domains kingdoms or both
Biochemicalrelationships
Molecular phylogenyanalyses the structures of many differentchemicals as well as the DN
to identity inter relationships betweengroupsoforganisms Thematchingcanevidencerelat
Gel electrophoresis a keytechnique
increasinglypatternsoe Dna or Rna fragmentsare used in
speciesidentification
comparsionsbetweenthe amino acidsequences o similar
proteins in dice rent species orgroups oforganismsareused
to help us classifythem or trace theirevolutionarypathways
Ciel electrophoresis isusedto separate DNA and RNA
fragments
proteins or aminoacids according to their sizeand
charge
thechemicals to be compared are placedinwells in
a getmedium in a bueeeringsolution with known DNA
or RNA Eragments proteins or aminoacids to aid
identification
Big DNA molecules are cut intofragments at specific
sites by the enzymes restrictionendonucleases
DNA Eragments are added to the gelcontaining a
dye The dye will bind to thefragments of DNA in
thegetand will fluoresce whenplacedunder ur
light
Electric current is passedthroughthe apparatus
and the DNAfragments move towards the positiveanode because of the
negative
charge on the phosphategroups in the Drum Fragmentswill move at differen
rates dependingon their mass andcharge
when moving is complete DNA Eluoresces and shows upclearlyso the
pattern
of the different bands can be identified
when comparing amino acids Ninhydrin is added to thegel when electrophoresis has
taken place No dyes are used Ninhydring reacts with the amino acids so they show
up as purplepatches and can be compared with known amino acids for identification
Two domains or three
Arenal replicatebybinary fission controlledwithin a cellcycle
Membrane structure oe the Aramea have an ether link in their lipidsgivingbranched
molecules that provide extra strength in extreme conditions
, tow many kingdoms
Systembased in morphologyresultingin a five Kingdomclassification
All prokaryotestogether in one Kingdom monera Animals plantsand the Eungi
Everythingelse such as all thesinglecelled organisms together in the protoctista
Thanks to biochemical and Dna evidence a new G Kingdomclassification is used
Archae bacteria Prokaryoticcells
Ancient bacteria with widevarietyoflifestylesincludeextremophiles bacteria that can
survive extreme conditions of heat cold pit Theynormallyreproduceasexually
Protoctista Eukaryoticcells
Kingdomincludes all the single celledorganismsNormallyreproduceasexually
Ingi Eukaryoticcells
Kingdomincludes both unicellularorganisms and multicellularorganisms All hetero
tropas Reproduce both asexually and sexually
Tanta e Eukaryotic cells
All multicellular almost all autotrophsthey make their food by photosynthesis Both
asexual and sexual reproduction occurs in this Kingdom
Animalia Eukaryotic cells
All multicellular all heterotrophs Theyinclude vertebrates and invertebrates Sexua
reproductionis common but asexual reproduction can also happen
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