Q.Which of these functions could or could not be carried out by a red blood cell? Briefly justify your answer.
a. Protein synthesis
b. Cell division
c. Lipid synthesis
d. Active transport

Step 1. Recall RBC structure. A mature mammalian red blood cell has discarded its nucleus, mitochondria, ribosomes and endoplasmic reticulum during development, keeping only its plasma membrane and cytoplasm packed with haemoglobin.

Step 2. Assess (a) Protein synthesis. Protein synthesis needs ribosomes to translate mRNA and, ultimately, a nucleus to transcribe genes in the first place - since the RBC has neither, it CANNOT carry out protein synthesis.

Step 3. Assess (b) Cell division. Cell division (mitosis) requires a nucleus containing DNA to replicate and segregate - without a nucleus, an RBC CANNOT divide; this is also why RBCs cannot repair or replace themselves and instead have a fixed 120-day lifespan.

Step 4. Assess (c) Lipid synthesis. Synthesising new lipids typically requires the smooth endoplasmic reticulum and associated enzymes - since these are absent, an RBC CANNOT carry out lipid synthesis. …

For each function, check whether it structurally requires a nucleus/ribosomes/ER (which the mature RBC lacks) or only require …

• Assuming that because an RBC lacks a nucleus it can do nothing at all metabolically - active transport does not require a nucleus. …