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Questions and Answers
PhyB induces the expression of lightresponsive genes involved in ______ synthesis.
PhyB induces the expression of lightresponsive genes involved in ______ synthesis.
chlorophyll
The response of plants to photoperiods is mediated by photoreceptors such as ______ and cryptochromes.
The response of plants to photoperiods is mediated by photoreceptors such as ______ and cryptochromes.
phytochromes
PhyB is also important for the regulation of the ______ clock, influencing the timing of physiological processes and responses to daily/light or dark cycles.
PhyB is also important for the regulation of the ______ clock, influencing the timing of physiological processes and responses to daily/light or dark cycles.
circadian
Phytochrome B interacts with other signalling pathways including those that are involving plant hormones such as ______ and auxins.
Phytochrome B interacts with other signalling pathways including those that are involving plant hormones such as ______ and auxins.
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Photoperiod is the duration of light and dark periods in a day, and it is a critical environmental cue that regulates ______ time in Arabidopsis thaliana and many other plants.
Photoperiod is the duration of light and dark periods in a day, and it is a critical environmental cue that regulates ______ time in Arabidopsis thaliana and many other plants.
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PhyB does this by inducing the expression of lightresponsive genes involved in ______ development, and inhibition of hypocotyl elongation.
PhyB does this by inducing the expression of lightresponsive genes involved in ______ development, and inhibition of hypocotyl elongation.
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Plants perceive and respond to environmental signals that regulate ______.
Plants perceive and respond to environmental signals that regulate ______.
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[Blank] is the term used to describe the regulation of plant growth and development in response to light.
[Blank] is the term used to describe the regulation of plant growth and development in response to light.
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Cryptochromes are important in the regulation of ______ such as the inactivation of COP1/SPA in the presence of light.
Cryptochromes are important in the regulation of ______ such as the inactivation of COP1/SPA in the presence of light.
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UV-B light serves as a stress signal for plants, inducing various ______ responses.
UV-B light serves as a stress signal for plants, inducing various ______ responses.
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The red component of light is involved in regulating plant growth and ______ during development.
The red component of light is involved in regulating plant growth and ______ during development.
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Plants detect and respond to environmental cues that induce ______ through various mechanisms.
Plants detect and respond to environmental cues that induce ______ through various mechanisms.
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Phytochromes are the primary photoreceptors responsible for ______ light and far red light.
Phytochromes are the primary photoreceptors responsible for ______ light and far red light.
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Phytochromobilin is a linear ______ which is produced inside plastids and is derived from heme.
Phytochromobilin is a linear ______ which is produced inside plastids and is derived from heme.
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Phytochromobilin is exported from the ______ to the cytosol where it attached to the PHY apoprotein.
Phytochromobilin is exported from the ______ to the cytosol where it attached to the PHY apoprotein.
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There are five phytochrome ______ in Angiosperms (phyA-E) which each play a different role in development.
There are five phytochrome ______ in Angiosperms (phyA-E) which each play a different role in development.
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The PAS-GAF-PHY domains consist of a ______ binding, photosensory region of phytochrome.
The PAS-GAF-PHY domains consist of a ______ binding, photosensory region of phytochrome.
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Phytochromes are dimeric ______ in which two apoproteins are covalently bound to phytochromobilin.
Phytochromes are dimeric ______ in which two apoproteins are covalently bound to phytochromobilin.
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Study Notes
Phytochrome B and Plant Development
- Phytochrome B (PhyB) is responsible for the transition from skotomorphogenesis (dark-grown state) to photomorphogenesis (light-grown state).
- PhyB induces the expression of light-responsive genes involved in chlorophyll synthesis, chloroplast development, and inhibition of hypocotyl elongation.
- This leads to the greening of seedlings and the establishment of photosynthetic capacity.
Interactions with Other Signalling Pathways
- PhyB interacts with other signalling pathways, including those involving plant hormones such as gibberellins (GA) and auxins.
- This interaction aids in coordinating plant growth and metabolism.
Regulation of Circadian Clock
- PhyB is important for the regulation of the circadian clock, influencing the timing of physiological processes and responses to daily light/dark cycles.
- This is critical for coordinating plant growth and metabolism.
Photoperiodism and Flowering Time
- Photoperiod is the duration of light and dark periods in a day, and it is a critical environmental cue that regulates flowering time in Arabidopsis thaliana and many other plants.
- Plants respond to photoperiods through photoreceptors such as phytochromes and cryptochromes.
- Cryptochromes are also important in the regulation of photomorphogenesis, such as the inactivation of COP1/SPA in the presence of light.
Perceiving and Responding to Environmental Signals
- Plants perceive and respond to environmental cues, including photoperiod, temperature, and light quality, to regulate flowering time.
- This response is mediated by photoreceptors such as phytochromes and cryptochromes.
Plant Nuclear Gene Expression
- The structure of a typical plant nuclear gene consists of various components, including promoters, enhancers, and coding regions.
- Regulation of plant nuclear gene expression involves mechanisms such as transcriptional activation, chromatin remodeling, and post-transcriptional modification.
Photomorphogenesis and Plant Development
- Photomorphogenesis is the process of plant development in response to light.
- Plants detect and respond to the red and far-red components of light during photomorphogenesis.
- Phytochrome photoreceptors are responsible for this response, with phytochrome B playing a key role in Arabidopsis thaliana.
Phytochrome Structure and Function
- Phytochromes are dimeric chromoproteins that consist of two apoproteins covalently bound to phytochromobilin.
- Phytochromobilin is a linear tetrapyrrole produced inside plastids and derived from the chlorophyll biosynthetic pathway.
- There are five phytochrome isoforms in Angiosperms (phyA-E), each playing a different role in development.
- Phytochrome structure includes domains such as PAS, GAF, and PHY, which are involved in chromophore binding and photosensory functions.
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Description
Phytochrome B is responsible for transitioning from dark-grown to light-grown state, inducing light-responsive genes for chlorophyll synthesis, chloroplast development, and inhibiting hypocotyl elongation. It leads to seedling greening and photosynthetic capacity establishment, and interacts with other plant hormone signaling pathways.
