circadian clock

Question 1

What is the floral clock, and how does it function?

Answer 1

• The floral clock regulates the timing of flower movements and developmental processes.
• It operates on a 24-hour cycle and ensures that the plant’s growth and flowering are synchronized with the day-night cycle.

Question 2

What are circadian rhythms and why are they important for plants?

Answer 2

• Circadian rhythms are near 24-hour cycles controlled by the internal biological clock.
• They help plants synchronize their development and metabolism with external environmental cues like light, optimizing growth, photosynthesis, and flowering.

Question 3

What are the main characteristics of circadian rhythms in plants?

Answer 3

• Persistence without external cues: Rhythms continue even in the absence of environmental signals.
• Resetting by external signals: Light and other cues adjust the timing.
• Temperature insensitivity: Temperature changes do not significantly affect the rhythm.

Question 4

What is entrainment, and why is it essential for the floral clock?

Answer 4

• Entrainment refers to synchronizing the circadian clock with the 24-hour day-night cycle.
• Light-on signals help reset the clock every day, ensuring the plant stays in phase with the changing seasons and photoperiod.

Question 5

How does light play a role in entrainment of the circadian clock?

Answer 5

• Photoreceptors like cryptochromes (blue light) and phytochromes (red and far-red light) help entrain the circadian clock to the changing light conditions.
• These photoreceptors reset the clock, aligning plant rhythms with the environment.

Question 6

What drives the circadian clock in plants?

Answer 6

• The clock is driven by oscillating gene expression involving negative feedback loops.
• Genes turn each other on and off, generating regular oscillations that control plant processes.

Question 7

What are overt rhythms in plants, and what do they result from?

Answer 7

• Overt rhythms are visible or measurable manifestations of circadian oscillations, such as growth patterns, leaf movements, and stomatal opening.
• These rhythms result from the internal oscillations of gene expression.

Question 8

How does the circadian clock control plant growth?

Answer 8

• The clock controls hypocotyl elongation and other growth processes by regulating the timing of gene expression.
• This ensures growth is optimized according to the day-night cycle.

Question 9

How does the circadian clock control plant development?

Answer 9

• The circadian clock helps regulate flowering by linking it to the photoperiod.
• It ensures that plants flower at the right time, depending on environmental signals like day length.

Question 10

How is the circadian oscillator structured in plants?

Answer 10

• The oscillator consists of negative feedback loops formed by various MYB transcription factors.
• These loops regulate gene expression to produce the rhythmic biological processes that define the plant’s circadian cycle.