MOLECULAR CELL BIOLOGY AND
GENETIC DISORDERS:
QUESTION AND ANSWERS
1. As cells grow and regenerate, what mechanism does the body use to get rid of the continuously
dying cells? And what kind of cells can’t be replaced once dead?
2. I cannot find out why some of the autosomal dominant diseases have a male or female
preponderance, e.g. I have never seen a female Marfans. I was attributing it to imprinting but on
reading about imprinting in detail it cannot be the case.
3. We have been told that some tumours in the colon are associated with microsatellite instability.
What does this mean?
4. I understand that microarrays are being used to define the molecular abnormality and the
prognosis in some patients with leukaemia. What are microarrays?
5. Why do mitochondrial diseases cause a myopathy?
6. Why do successive generations of patients with some genetic disorders present earlier and with
progressively worse symptoms.
7. Does a normal serum uric acid level exclude the diagnosis of Lesch–Nyhan syndrome?
8. How is retinoblastoma an autosomal dominant disease if the mutation of both RB genes is
required to express the disease?
ANS:
1. Cells are continually dying by a process of apoptosis (programmed cell death). These cells (or
their fragments) are phagocytosed by macrophages or neutrophils where they undergo autolysis
within these phagosomes. Brain cells cannot be replaced when dead, although recent evidence
challenges this view. Further reading Voss H. V. et al (2006) Journal of Clinical Investigation 116:
2005–2011
GENETIC DISORDERS:
QUESTION AND ANSWERS
1. As cells grow and regenerate, what mechanism does the body use to get rid of the continuously
dying cells? And what kind of cells can’t be replaced once dead?
2. I cannot find out why some of the autosomal dominant diseases have a male or female
preponderance, e.g. I have never seen a female Marfans. I was attributing it to imprinting but on
reading about imprinting in detail it cannot be the case.
3. We have been told that some tumours in the colon are associated with microsatellite instability.
What does this mean?
4. I understand that microarrays are being used to define the molecular abnormality and the
prognosis in some patients with leukaemia. What are microarrays?
5. Why do mitochondrial diseases cause a myopathy?
6. Why do successive generations of patients with some genetic disorders present earlier and with
progressively worse symptoms.
7. Does a normal serum uric acid level exclude the diagnosis of Lesch–Nyhan syndrome?
8. How is retinoblastoma an autosomal dominant disease if the mutation of both RB genes is
required to express the disease?
ANS:
1. Cells are continually dying by a process of apoptosis (programmed cell death). These cells (or
their fragments) are phagocytosed by macrophages or neutrophils where they undergo autolysis
within these phagosomes. Brain cells cannot be replaced when dead, although recent evidence
challenges this view. Further reading Voss H. V. et al (2006) Journal of Clinical Investigation 116:
2005–2011
