Exercises: Stem Cells

Define the term stem cell and name two characteristics that distinguish stem cells from other cells.

Name two sources of stem cells and state whether each is likely to be embryonic or adult.

Explain the difference between totipotent, pluripotent and multipotent stem cells.

Bone marrow transplants are used to treat leukaemia.

1. a) Identify the type of stem cell found in bone marrow.

1. b) State the types of cell these stem cells can produce.

1. c) Explain why the donor must be closely matched to the patient.

Therapeutic cloning involves transferring the nucleus of a patient's somatic cell into an enucleated egg cell and growing the resulting embryo to obtain stem cells.

1. a) Outline the steps in this process.

1. b) Explain why the stem cells produced are unlikely to be rejected by the patient.

1. c) State one difference between therapeutic cloning and reproductive cloning.

Stem cells can be used to grow skin for burn victims and may one day treat conditions such as Parkinson's disease.

1. a) Explain how stem cells can be used to regenerate damaged tissue.

1. b) State one risk associated with the use of stem cells in therapy.

1. c) Explain why embryonic stem cells are of more interest than adult stem cells for treating a wide range of conditions.

A debate takes place in a Dublin school on the use of human embryos in stem cell research.

1. a) Present one argument in favour of this research and one against.

1. b) Outline an alternative source of pluripotent cells that avoids the use of embryos.

1. c) Evaluate how scientific knowledge and ethical judgement each contribute to deciding whether this research should be permitted.

All the cells of an adult human have essentially the same genome, yet a neuron and a muscle cell differ greatly.

1. a) Explain how cells with the same genome can become specialised.

1. b) Explain how this relates to the potency of stem cells.

1. c) Explain why a stem cell differentiating into a specific tissue is described as a change in gene expression and not in DNA content.

Dolly the sheep was produced by transferring the nucleus of a mammary gland cell into an enucleated egg.

1. a) Explain what Dolly's creation showed about the genetic material of differentiated cells.

1. b) Explain why Dolly was genetically identical to the nucleus donor in nuclear DNA, but not necessarily in mitochondrial DNA.

1. c) Discuss one reason why reproductive cloning of humans is widely opposed.