L7-8: Eukaryotic Organisms Flashcards
What are ideal characteristics of model organisms?
Rapid rate of development
Easily manipulates
Short life span
Readily available
Large numbers offspring per generation
Why is E.coli a good model?
Simple & free-living, gram negative rod shaped bacterium, easy to grow, easy to genetically manipulate and transform
What is a homologue?
A gene related to another gene by descent for a common ancestral DNA sequence (relationship between genes in different species or event of genetic duplication)
What is an orthologue?
Genes in different species that evolved from a common ancestral gene, retain the same/similar function in the course of evolution
What is a paralogue?
They are genes generated by a duplication event
What is a gene knockout?
Gene sequences are completely or partially removed and gene expression is completely eliminated
What is gene knockdown?
Techniques that reduce/interfere with the expression of the gene
What are the 2 major yeast genetic models?
Saccharomyces cerevisiae (budding) and Schizosaccharomyces pombe (fission)
Why is yeast a good model?
Small size and simple growth and storage conditions, rapid growth rate, exist as diploid or haploid
What are advantageous genetic factors of yeast?
Sexual cycle enables large scale genetic crosses, construction of gene knockouts and gene knock-ins is trivial, easily transformable with plasmids, large mutant collections and genetic crosses and screening may be automated
What are advantageous characteristics of Drosophilia melanogaster?
Small (large numbers cheaply maintained), small life cycle with lots of offspring produces,
What are advantageous genetics of Drosophilia melanogaster?
Easy to cross, huge number of mutants available, phenotypic markers, mature larvae allow genetic mapping, transformable using P element transposon, create both deletion and insertion mutations and can do tissue specific knockdowns or deletions
What biological processes has Drosophila helped understand?
Cell signalling
Development
Neurological diseases
What are some advantageous characteristics in Caenorhabditis elegans?
Small, transparent, feed on bacteria so cheaply maintained, short life cycle, short lifespan (2-3 wekks), extremely fecund (hermaphrodites can produce ~300 offspring)
What are some advantageous genetics in Caenorhabditis elegans?
Easy to perform genetic crosses, many mutants available, transformable, genes can be knocked down using RNA interference
What are advantageous characteristics of zebrafish?
Sexually mature by 3-4 months old and have transparent embryos
What are advantageous genetics of zebrafish?
Sturdy 1mm embryos, possible to make mutants by random mutagenesis, methods for manipulation genomic DNA, knockdown of expression of specific genes is possible using morphlinos
What are advantageous mouse characteristics?
Most closely related to humans
What are advantageous mouse genetics?
2 month breeding cycle, inbreeding (identical genetic composition), manipulations of embryonic stem cells (transgenic mice), production of mouse knockouts
What are the advantages and disadvantages of mouse disease models?
Pros: powerful approach understanding the role of a particular gene in a model and its role in disease
Cons: Production of knockouts is very expensive and time consuming (ethical implications too)
What are characteristics of eukaryotic nuclear genomes?
Split into linear set of chromosomes, have at least 2 chromosomes, have multiple origins of replication
What are the names of the staining patterns in chromosomes?
G-banding (dark AT rich), R-banding (dark GC rich), Q-banding (dark AT rich) and C-banding (dark constitutive heterochromatin)
What do decondensed chromosomes do when not undergoing division?
They occupy a specific territory within the nucleus
What are centromeres?
Where sister chromatids are held together
