🧬 What are Chromosomes?

🔄 Chromosome Formation:

• When the cell is not dividing, chromatin looks like a loose web spread throughout the nucleus.
• But when the cell prepares to divide, chromatin condenses (tightens up) into chromosomes.

📎 Example: You know how earphones are tangled in your pocket? That’s like chromatin. When you neatly roll them up, it’s like a chromosome – compact and ready to use.

🧩 Structure of a Chromosome:

Each chromosome:

• Has two identical arms called chromatids.
• The two chromatids are joined in the middle by a point called the centromere.

🔍 Visualize it like an X-shape, where the center of X is the centromere, and the arms are chromatids.

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📊 Chromosome Numbers – Species Specific

Species	Number of Chromosomes
Humans	46 (23 pairs)
Some ants & worms	2
Indian fern (Ophioglossum)	1260

🔑 Note: More chromosomes ≠ more complex organism. A fern has more chromosomes than humans, but that doesn’t mean it is more advanced.

🧠 Mnemonic: “Hi So InC”

• Hi = Humans → 46
• So = Some ants/worms → 2
• InC = Indian fern Count → 1260

✅ Helps you remember that chromosome number is unique to each species but doesn’t show how complex it is.