2 Model Organisms - A Consequence Of The Tree Of Life Flashcards
How does the tree of life allow us to use model organisms
Organisms can be studied, and parallels can be drawn between those discovering and the human species, which will be a key development of new medicine
Evidence from shared molecules / structures / processes - one tree of life meaning you can study these aspects in one organism and compare it to human processes
The cell cycle
Fission Yeast
Control of cell division is fundamental to orgasmismal development and function. Loss of control can lead to cancer (metastatic cancer - over replicating cells that also spread across tissues and organ systems).
Model organism - Fission yeast
Ascomycete fungus / model eukaryotic —> cell cycle regulation system in fission yeast is the same in humans
What makes a good model system
Experimental requirements —> phenotype of interest is ancestral / basis of phenotype is conserved
Allows one to address a particular question in one species to tell us about many species
Homologous and not analogous traits
Model organism - E.Coli (description)
Gamma proteobacterium - Isolated from the gut / fast growing in optimal conditions = 20 minute division time
Commensal strains of low pathogenicity (eg. K12)
Related to disease causing strains and species - shingles, E.coli O510, E.coli UPEC
Model organism - E.coli (biotech workhorse)
Easy to insert plasmids into E.coli
Can engineer plasmids to make focal proteins
Biotech and medical applications - Eg. Recombinent insulin / recombinent growth hormones
Model organism - thale cress (description)
Braassicaceae - included important crop plants / annual weed type species - grows fast and seeds very early (fast life cycle)
Model organism - thale cress (key features)
Small genome for a plant - 157Mb
Genetically manipulable
Self-fertile so maintains homozygous lines
Can store seed in a small place
Model organism - C.elegans (description)
Nematode worm
Related to parasitic worms causing disease in humans, livestock, other animals and plants
Model organism - C.elegans (key features)
Rapid development, eats bacteria you can grow on a plate
Hermaphrodite - easy to maintain stocks and mutations but can be crossed as produces males when stressed
Translucent at all life stages - easy to screen and visualise changes / mutations
Simple neurological system
C.elegans share fewer human physiological systems and gene homologs (roughly 65%) than fruit flies theyre able to provide invaluable insights into conserved molecular processes —> useful for drug screening.
Determinate development - 959 cells in adult hermaphrodite
Model organism - C.elegans (gene expresion regulation)
Can express these interfering RNA in E.coli. Feed to C.elegans and it knocks down individual gene function
Model organism - drosophila melanogaster (description)
Fruit fly
Related to mosquitoes - major vector of disease
Complete metamorphosis (egg —> maggot —> pupa —> adult) takes 10 days on simple banana medium
Model organism - drosophila melanogaster (key features)
Visable ‘polytene’ chromosomes
Can see individual chromosomal deletions and inversions
Inverted ‘balancer’ chromosomes - retain recessive deleterious mutations indefinitely
Model organism - drosophila melanogaster (embryonic development)
orchestrated by expression of genes that give positional information (Hox genes)
orchestrated by expression of genes that give positional information (innate immunity)
antimicrobial system that runs complementary to adaptive (AB based) immunity in vertebrates
