Q3. Differentiate between the following pairs of terms:
- (i)) Polar microtubules and Kinetochore microtubules (100 words)
- (ii)) Diplotene and Diakinesis (100 words)
- (iii)) Primary active transport and Secondary active transport (100 words)
- (iv)) Desmosomes and Hemidesmosomes (100 words)
Key Points:
- Kinetochore microtubules attach to chromosome kinetochores, while polar microtubules overlap at the spindle equator.
- Diplotene is marked by chiasmata; Diakinesis shows maximum chromosome condensation and nuclear envelope breakdown.
- Primary active transport uses direct ATP hydrolysis; secondary active transport uses established ion gradients.
- Desmosomes mediate cell-to-cell adhesion; Hemidesmosomes anchor cells to the extracellular matrix.
Answer: Polar microtubules and kinetochore microtubules are both essential components of the mitotic spindle, originating from the centrosomes. However, they differ significantly in their attachment points and primary functions during cell division. Polar microtubules (also called interpolar microtubules) extend from each spindle pole towards the opposite pole, overlapping at the spindle equator. They do not attach to chromosomes but are crucial for maintaining the structural integrity of the spindle a...