Lesson 3 ·Class 10 · Structure of Chromosomes, Cell Cycle and Cell Division · Label Lab
Inside a Chromosome
Chromatid, centromere, arms and genes.
Tap any part of the diagram to learn its name and its job.
Free play — explore the diagram, or switch to "Label it yourself" and place every label. Switch to when you're ready to test yourself.
This is a DUPLICATED chromosome, which is why it looks like an X. It is still counted as ONE chromosome, because the two chromatids share a single centromere — that is the definition worth holding on to when you meet mitosis.
What this lesson covers
The parts you label
- Chromatid — One of the two identical threads of a duplicated chromosome.
- Sister chromatid — Its identical partner, produced when the DNA was copied in S phase.
- Centromere — The constriction joining the two chromatids, and the point that attaches to the spindle. One centromere means one chromosome.
- Short arm (p) — The shorter section above the centromere.
- Long arm (q) — The longer section below the centromere.
- Gene — A segment of DNA at a fixed position, controlling one character.
- Telomere — The protective cap at the end of each arm.
Challenges to clear
- Tap the part that attaches to the spindle — and that decides whether this counts as one chromosome or two.
- Tap the segment that controls a single character.
- Label the whole chromosome.
Hint
This is a DUPLICATED chromosome, which is why it looks like an X. It is still counted as ONE chromosome, because the two chromatids share a single centromere — that is the definition worth holding on to when you meet mitosis.