B2.2 & B2.3 Compartmentalisation and Specialisation

Question 1

What are the advantages of the separation of nucleus and cytoplasm?

Answer 1

Post-transcriptional modification can happen before the mRNA meets ribosomes in the cytoplasm. Not possible in prokaryotes.

Question 2

Advantages of compartmentalization in the cytoplasm of cells

Answer 2

• Enzymes and substrates can be more concentrated
• Substances that can cause damage to the cell can be kept inside the membrane of an organelle.
• pH can be maintained at optimum level for a particular process.
• Organelles can be moved around with their content.

Question 3

What are considered organelles?

Answer 3

YES: Nuclei, vesicles, ribosomes, and plasma membrane.
NO: cell wall, cytoskeleton, and cytoplasm.

Question 4

What are the constraints with cell size?

Answer 4

• The surface area to volume ratio of a cell limits the size the cell can reach.
• Exchange of materials across a cell surface depends on its area.
• The need for exchange depends on cell volume.
• As the width of an object such as a cell increases, the SA increases, but at a much slower rate than the volume.
• When there is insufficient SA to support a cell’s increasing volume, the cell will either divide or die.