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#Polycomb proteins

3 public questions tagged with this topic.

Eukaryotic chromatin and chromosome

Polycomb proteins cause:

Polycomb group proteins maintain developmental regulators silenced through epigenetic memory. PRC2 complex containing EZH2, EED, SUZ12 catalyzes H3K27 trimethylation, PRC1 containing BMI1, RING1B ubiquitinates histone H2A at lysine 119 and compacts chromatin, blocking SWI/SNF remodeling and preventing RNA polymerase II elongation. Targets include HOX clusters and lineage transcription factors. Compaction renders chromatin inaccessible. Polycomb loss results in ectopic gene activation and homeotic transformations. Unlike constitutive activators, Polycomb establishes facultative heterochromatin reversible during differentiation and reprogramming processes, ensuring cell identity maintenance.

Ref: Lewis Polycomb 1978; Lodish et al., Molecular Cell Biology, Chapter 8: Polycomb Proteins Cause Gene Repression

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ABC MODEL+PYQS

Trithorax proteins function opposite to Polycomb by:

C fits best: Activating floral genes. Keep the ABC MODEL basics straight and Activating floral genes stands out as the precise answer. Avoid: A) Repressing flowering; B) Silencing chromatin; D) Degrading DNA. Light and flowering items often hinge on which photoreceptor or day-length rule is in play.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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ABC MODEL+PYQS

Polycomb proteins regulate flowering by:

The right choice is B: Repressing floral genes. In ABC MODEL, that matches how the process or concept actually works — the other choices mix up related ideas or use the wrong mechanism. Skip these: A) Activating MADS-box genes; C) Degrading transcription factors; D) Transporting hormones. A quick check: if an option needs energy, pumps, or the opposite direction of movement, ask whether that really applies.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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