13505046
Description
Flashcards by J yadonknow, updated more than 1 year ago
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Created by J yadonknow
about 6 years ago
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| Question | Answer |
| Problems w/ crop research | Big plants Long generation times Often complex genomes Difficult to genetically manipulate |
| Arabidopsis thaliana | Small short generation time small genome easy to genetically manipulate |
| Germination | Requires water, O2, light Cotyledon Hypocotyl root |
| Etiolated plant | If seed germinates and doesn't detect light Extended hypocotyl Cotyledons don't unfold Seedling still thinks it's underground, seed reserve runs out |
| Phytochrome | Photoreceptor Abrobs red and far-red light(600-750nm) Can also absorb blue light (350-500nm) and UV-A (320nm-400nm) |
| Phytochrome structure | N-terminal Phytochromobillin Photosensory domain Regulatory domain C-terminal |
| Phytochromobillin | Chromophore Red light=Pfr (active) Far red light=Pr (inactive/dark) |
| Phytochrome overview | Pr converted to Pfr by red light Induces conformation change Translocates to nucleus from cytosol influences gene expression Germination initiated |
| PhyA mutant | Plants w/ knockout PHYA (phytochrome) can't detect light Look etiolated Proof that phytochromes have a key role in light sensing |
| Differing light quality | Light available at canopy Not at understory seedlings wait until gap in canopy to start germinating |
| Why living on a rotating planet is biologically stressful | Large variation in enviro conditions including: 'C/L.I./humidity |
| Circadian clocks | Biological oscillators w/ ~24hr period |
| What defines a circadian rhythm? | Three parameters: Period - time between comparable points Amplitude-height btw. peak+troughs Phase-any point in cycle that's distinct |
| Clock mechanism | Night: Gene 2 is active, producing 2 protein. Dawn: Accumulation of 2 until it reaches a level where it activates expression from gene X and gene Y. Day: X and Y protein accumulate. Inhibit expression of gene 2. NEGATIVE FEEDBACK LOOP. |
| Requirements for identifying clock components | Luciferase - luminescent reporter protein from fireflies Promoter crontolled by clock |
| Method | Put promoter controlled by clock in front of gene you think responds to clock effect. |
| Reporter complex | Look at luciferase expression through a microscope, pulsing of luciferase in fluorescent dye Randomly mutate plant and look l ook at changes circadian oscillations |
| Temperature compensated | Circadian clock runs at same speed regardless of temperature Subject to physics, each step will run faster as temp ^, however responses will compensate each other i.e. ^rate of synthesis = ^rate of degradation |
| Entrainment | In constant darkness clock begins to run out of sync In natural conditions clock checks the natural environment to 'reset' itself This is called entrainment |
| What entrains the clock in plants? | Phytochrome |
| Components of the circadian clock | Central oscillator - a -FDBCK loop Input for entrainment to local conditions - phytochrome Output to effect responses - alter gene expession |
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