Model Organisms For Genetic Analysis Flashcards
Define a model organism
Well established biological system used to help understand biology and disease
what are the main characteristics of a model organism
Rapid development/maturity Ability to transform Large number of mutants Large offspring number Fast cell cycle Sequenced genome
Why are large number of offspring advantage in model organisms
Can do big generic crosses
What are the 5 model organism used
Worm, zebra fly , budding/fission yeast , mouse
Which model organism is a unicellular eukaryote with linear chromosomes
Yeast
What makes budding yeast and fission yeast a model organism
Rapid and simple growth eg on agar Large scale genetic crosses available Gene knockouts are constructed easily Can be transformed with plasmids Large number of mutants eg gfp
What properties do yeast have similar to humans
Cell division cycle
Gene expression
Dna replication
What are yeast transformable in
Plasmids
How are budding and fission yeast different
Evolutionary divergent. Some genes are not present in budding but are in fission
Which model organism is more useful than yeast only due to the fact it’s multicellular
Fruit flies
Explain why fruit flies are good model organisms
Large number of mutants Large number of eggs laid in a day Large number can be maintained (small) Can create knockdowns Can create deletion/insertion mutations
How are fruit flies transformed
By transporons - genes/dna that can move location on a genome
What are the 3 bigger contributions coming from fruit flies
Cell signalling pathways of oncogenes were identified (cancer)
Embryo development insights via analysis of fly development
Neurological disease model- gave insight to human conditions eg SMA and Alzheimer’s
(Eg flies that had mutant SNM gene had phenotypes of SMA disease)
What is a disease model
Mutant organism that mimics features of human disease (eg an orthologue gene which was mutant)
What is the main thing worms are used for in genetic experiments
Studying ageing and development- their life cycle is very short and each cell can be monitored via development
Other than short life span of worms what else makes it a model organism
Many mutants available
2 sexes allows big genetic crosses
Large number of offspring
Gene knockdowns via siRna
Explain how gene knockdowns are induced in worms
Bacteria with double strand RNA is ingested by the worm
This produces siRNA
SiRNA Then prevents gene expression (targets specific genes)
What was produced due to model organism worm
First extension to life span mutant
Give some ways zebra fish are model organisms
Lay many eggs
Sexually mature quick
Embryos can be developed externally and are transparent
How can mutations be induced in zebra fish
random mutagenesis
How are knockdowns induced in zebra fish
Using morpholinos -
Nucleotide oligomers that block expression
What are zebra fish good models for
Vertebrate development
Diseases like cancer
Drug discovery
What is the model organism closest related to humans (many orthologue genes)
Mouse - mammalian model
Why are mice used as model organisms
Short breeding cycle
Can inbreed to get offspring with same genes
Can produce transgenic mice
Explain the way to produce transgenic mice with knockouts
Embryonic stem cells with knockout genes inserted into embryo of mouse
Mouse develops and reproduces hybrid mice
After many many breeds, a KO MOUSE IS PRODUCED WITH KNOCKOUTS
Why is it a disadvantage to use transgenic mice to produce knockouts to study disease
Takes too long and is expensive
How was a mutant mouse used to study diabetes / obesity
The ob ob mouse with no leptin gene (appetite control) became obese and developed symptoms of diabetes = leptin is linked
What other diseases apart from diabetes and leptin gene have been indetified due to KO mice
Cystic fibrosis- the mouse have CFTR gene knockout
Cancer
