Model organisms Flashcards
Name what these model organisms are used for?
Escherichia coli
Saccharomyces cerevisiae – yeast
Schizosaccharomyces pombe – yeast –
Neurospora crassa – fungus –
Mus musculus – mouse –
Caenorhabditis elegans –
Drosophila melanogaster –
Xenopus laevis –
Arabidopsis thaliana –
Oryza sativa – rice,
Escherichia coli – used to understand basics of DNA replication
Saccharomyces cerevisiae – yeast – used to understand basic cell biology
Schizosaccharomyces pombe – yeast – used to understand cell cycle
Neurospora crassa – fungus – used to understand growth and circadian clock
Mus musculus – mouse – used extensively in cancer and disease models
Caenorhabditis elegans – nematode worm - used to understand development
Drosophila melanogaster – used to understand development, behaviour
Xenopus laevis – used to understand gene function and electrophysiology
Arabidopsis thaliana – dicot - used very extensively in all aspects of plant biology
Oryza sativa – rice, monocot – used as a model for crop and monocot biology.
Why is Arabidopsis used as a model organism for genetic studies?
Diploid and self-fertile
Outcrossing
easy
low contamination rates
Small size (fully sequenced genome 25000 genes 125 Mb)
high density growth
Fecundity
thousands of seeds
Easy transformation-Agrobacterium tumefaciens
T-DNA insertion lines
Easy mutagenesis
Literature
Techniques
core eukaryotic oscillator
What are the main inputs and outputs
inputs=light and temperature
outputs= gene expression, changes in physiology and behaviour through compartmentalization of metabolism. Helps to optimise internal workings of the cell
oscillator allows it to be self sustaining
these inputs then allow for the positive or negative elements to be activated or suppressed, as well as phosphorylation or degradation
What are the characteristics of the circadian oscillator?
entrainable by input stimulus
robust in free running conditions
temperature compensated
canonical clocks are transcriptional (but they don’t have to be)
Why do plants bother having circadian rhythms?
helps them coordinate responses to flowering and other predictable things such as responding to caterpillars by releasing chemicals
Explain other circadian behaviours in plants
Plant circadian movement:
Hypocotyl growth
Petal opening
Describe;
Period.
Phase.
Amplitude.
Entrainment (e.g. 16L/8D).
Free-Run (e.g. LL or DD).
Period= Whole S
Phase=the exact same point when it is repeated
Amplitude=height of the waves
Entrainment (e.g. 16L/8D)= photoperiod we use to set up the oscillator (16 hours light)
Free-Run (e.g. LL or DD)=if its a circadian rhythm when an input is changed the rhythm would still stay the same, if the rhythm is lost after you switch the lights off then it is a diurnal response.
Describe some circadian behaviour in plants
Gene expression
Cytosolic calcium levels
Stomatal opening
Chloroplast movement
Starch utilization
Ca2+ and photoperiodic flowering
[Ca2+] fluctuates with a strong circadian rhythm in constant light in Arabidopsis. This is measured by using a jellyfish protein (aequorin) that will illuminate in the presence of calcium
The circadian clock is important for fungi and plant interactions?
General phenomena found in many plants and fungi
Anticipation of future challenges
Prime plant defences
Release fungal spores at optimal time(s) of day
~1/3 plant genes regulated
~40% of Neurospora crassa transcriptome regulated
