Model Organisms Flashcards
Why are biological models used?
- can ethically experiment with them
- used as a biological tool
- represents something that is too small, or large or complex
What is a model organism? Inc examples.
- non-human species
- an organism extensively studied to understand particular biological processes
- e.g. yeast, e.coli, mice, drosophola
What is developmental biology?
- the study of processes underlying how organisms grow and develop (e.g. embryogenesis)
Why is developmental biology important?
- to understand birth defects
- research into stem cells has lead onto cloning of tissues and organs
What are good characteristics that you would expect a model organism to have?
- common features and conservation of metabolic and developmental pathways
- sequenced genome with conserved regions similar to humans
- easy to mutate and carry out molecular techniques
- small with a short life cycle
- cheap and easy to keep and handle
What are some considerations when choosing a model organism for research?
Biological considerations: - is this organism biologically suitable Practical considerations: - costs - space - ease of breeding / handling Historical considerations: - previous research on that organism
Name some vertebrate model organisms.
- mouse
- chicken
- frog
Give reasons as to why mice are used as model organisms.
- history as a mammalian model
- lots known about its biology
- homologues cell types to humans
- genome sequenced
- reverse genetics: genes have been “knocked out”
- large mutant collections
- construction of chimeric embryos possible
- source of primary cells for culture
What are the disadvantages of the mouse as a model organism?
- complex animals, genomes as large as humans
- embryonic manipulation is difficult as embryo develops in utero (cannot see what is happening as develops inside the mother)
- mother mouse can stop the embryo from developing further if it is defected
- long generation interval (the quicker to get to adulthood the better)
- embryo culture is difficult
Give reasons as to why chickens are used as model organisms.
- large eggs (not too small to work with)
- accessible embryo
- easy to manipulate
- easily infected by avian retroviruses
- low cost
- early processes occur in a very short amount of time, heart/circulatory systems developing on day 2
- sequencing data is available
What are the disadvantages of the chicken as a model organism?
- not good for classical genetics
- complex genome
- limited genetic resources
Give reasons as to why frogs are used as model organisms.
- lots of biological information
- accesible embryo
- robust embryo, can culture part of the embryo
- excellent experimental embryology
- ectopic gene expression possible in early embryos
- rapid development
What are the disadvantages of the frog as a model organism?
- not as many genetic resources
- complex genome only sequenced recently
- difficult to create transgenic animals
- lower reproduction
Name some invertebrate model organisms.
- Fruit fly (Drosophila)
- Round worm (C.elegans)
- Sea urchin
Give reasons as to why Drosophila is used as a model organism
- excellent genetics (sequences)
- very readily available
- targeted gene disruptions
- fast generation time, many offsprings
- powerful molecular techniques
- transgenic animals easily generated
- small and easy to grow
- can create homoetic mutants
- eptopic gene expression (limbs on head thing)
