Polytene chromosomes, initially termed a 'permanent spireme' by Balbiani in 1881, were first identified in various tissues of Chironomus plumosus larvae. These tissues include salivary glands, Malpighian tubules, intestine, hypoderm, and muscles. The chromosomes were described as a cylindrical cord that repeatedly unraveled and filled the nucleus.
Confirmation of Non-Continuity:
Giant Size Explanation:
Terminology Adoption:
Mitosis Elimination:
DNA Strand Behavior:
Inability for Mitosis:
Intact Nuclear Structure:
Developmental Context:
Varied Morphology:
Development from Diploid Nuclei:
Types of Polyteny:
Classic Polytene Chromosomes:
Cryptic Polyteny (Reticular Structure):
Pompon-like Chromosome:
General Morphology:
Distinct X-Chromosome in Males:
Role of Y Chromosome in Males:
Chromocentre Formation:
Types of Heterochromatin in Drosophila:
Variability in Chromocentre Formation:
Distribution and Characteristics:
Functional Distinction:
Cell Growth vs. Division:
Chromosome Structure:
Polyteny Levels (C):
Chromomeres and Banding:
Stability and Specificity:
Dynamic Structure:
Definition:
Precision in Synapsis:
Occurrence:
Frequency in Drosophila melanogaster:
Influence of Factors:
Genome Band Estimate:
Euchromatin Characteristics:
Interbands Definition and Characteristics:
Proteins in Interbands:
Genetic Organization:
Accurate Gene Mapping:
Visualization of Heterozygous Inversions:
First Meiotic Division:
Size Comparison:
Protein-Dependent Differentiation:
Transcriptional Activity Types:
Conformation of DNA Axis:
Open and Locked Chromatin:
Association with Protein Bodies (PBs):
Model for Transcriptional Regulation:
Microchromosome Transcription Activity:
Analyses Based on Side Loops:
Variability with Reproductive Cycle:
Polymerase-Based Classification:
Division Based on Transcriptional Units:
Chromosome Structure Modification:
Role of "Constitutive" Nucleosomes:
Active vs. Inactive Chromatin:
Asymmetrical Mantle and Loop Length:
Transcription Rate and Loop Length:
Consistency in Chromosome Maps:
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1. What are polytene chromosomes and why are they considered peculiar? |
2. How do polytene chromosomes differ from regular chromosomes in terms of their banding pattern? |
3. What is the significance of puffs in polytene chromosomes? |
4. Can polytene chromosomes be found in all organisms? |
5. How are polytene chromosomes molecularly organized within the bands and interbands? |
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