Week 2 Flashcards
What are the 2 types of seeded plants?
Gymnosperms
Angiosperms
What are the 2 types of Angiosperms?
Monocotyledonous
Dicotyledonous
What are the features of Gymnosperms?
‘Naked’ seeds e.g conifers
phylum - Pinophyta
What are the features of Angiosperms?
‘Vessel’ seeds e.g flowering plants
phylum - Magnoliophyta
What are the classification of Monocotyledonous?
Embryo with single cotyledon
Class Liliosida e.g Gramineae, Poacaeae, embryo
What are the classification of Dicotyledonous?
Embryo with two cotyledons
Class - Magnoliopsida
What are the key features of monocots?
One leaf
Parallel venations
Scattered bascular bundles
Flowers in multiples of 3
No true secondary growth
What are the key features of dicots?
Two seeded leaves
Reticulate venation
Vascular bundles in a ring
Flower parts not in multiples of 3
True secondary growth
When did dicots split off from monocots?
Around 150 - 200 MYA
When did Charles Darwin do his experiments on phototropism?
1880
What 3 different shoots did Darwin experiment on?
Used a light source on:
Intact seedling
Tip of coleoptile excised
Opaque cap on tip
What were the results of Darwins experiements?
Intact seedling moved towards light
Niether the shoot with the tip covered and cut off moved towards the light
When were the follow up experiments by Boysen-Jensen underwent?
1913
What were the 3 experiements that Boysen-Jensen did?
Shoot had mica sheet inserted into the dark side
Shoot has mica sheet inserted into the light side
Shoot were tip was removed then glued back on the celeoptile stump using gelatin
What were the results of the experiments done by Boysen-Jensen?
Shoot with the mica sheet inserted into dark side didnt bend towards the light
Shoot with the mica sheet inserted into light side bent towards the light
Shoot where the tip was removed then reattached bent towards the light
What makes a good model organism?
Comparatively easy to study (things like rapid life cycle)
Findings can be broadly applied
Knowledge and resources can be shared
What plant species make good model organisms?
Marchantia polymorpha (liverwort)
Physcomitrella patens (a moss)
Oryza sativa (Rice)
Triticum aestivum (Wheat)
Solanum lycopersicum (Tomato)
What plant species are used to characterise the cellular basis of important traits?
Arabidopsis thaliana (Mouse ear cress)
Oryza sativa
Medicago truncatula (a legume)
Why is Arabidopsis thaliana a good model organism?
Fully sequenced (first plant) small genome - 5 chromosomes, ~25,000 genes
High density of genes
Extensive natural selection
Short lifecycle
Widely avaliabily of knowledge
Easy to genetically modify
How would you generate mutants for genetic analysis?
Mutate a seed using chemicals
Grow seeds
Self fertilise seeds to produce M1 generation seeds
Seeds grown into M2 generation, the mutant sector should produce a ratio of 1:2:1 of seeds 2 wildtypes: seeds with 1 wildtype and 1 mutation: 1 with 2 mutation genes
What the overview of Arabidopsis thaliana basic biology and phylogeny?
Apart of Brassicaceae
Dicot
Both summer annual and winter annual forms depending on conditions
Is not outcrosser - self pollinates, populations stay isogenic
Diploid
What are the growth phases of Arabidopsis thaliana?
Two growth phrases:
Vegetative
Reproductive phrase
What happens in the vegetative phrase in Arabidopsis thaliana?
Vegetative growth is when the plant grows a small rosette of leaves to phototsynthesise
What happens in the reproductive phrase in Arabidopsis thaliana?
The plant produces inflorescence - small white flowers
Seeds form in pods called siliques
What happens to Arabidopsis thaliana during periods of short day conditions?
The plant suppreses flowering
Plants grow larger rosettes
What happens to Arabidopsis thaliana during periods of long day conditions?
The plant grows flowers
Plants have smaller rosettes
How long is the complete life cycle of Arabidopsis thaliana?
Depending on conditions can be done in 6-8 weeks
Why are Arabidopsis thaliana useful for experiments?
Very easy to grow on petri dish, in growth chambers
This allows for control with light and temperature
Isogenic genetics allows for easy reproducibility of results
Easy to genetically modify
How would you genetically modify Arabidopsis thaliana?
Grow until it flowers
Dip flowers into a culture of Agrobacterium containing gene construct of choice
Collect the seed
What two research projects about Arabidopsis thaliana allow for improvement of crops?
Research into circadian clock in Arabidopsis thaliana found gene PRR7 which turns out to be the difference spring and winter wheat
Epigenetics modifications of histones in Arabidopsis thaliana leads to flowering after winter which is the same process in the oilseed rape showing how crops will respond to climate chage
What is pangenomics?
The pangenomics is a set of genomes that capture the natural variation in the species
What other Arabidopsis that are important to research?
Arabidopsis lyrata (diploid)
Arabidopsis halleri (diploid)
Arabidopsis arenosa (tetraploid)
Arabidopsis kamchatika (tetraploid)
