Learning question: What is cloning? Is it morally right to clone?

Title: Cloning

Homework: exams next week! Study, study, study!

20 April 2023

Learning Objectives

(d) outline the potential for cloning human embryos in order to create a supply of embryonic stem cells for therapeutic use and ‘designer babies’ in reproductive cloning (HSW6a, 6b, 7c);

(e) discuss the ethical issues involved in therapeutic and reproductive cloning and in transplant surgery (HSW6a, 6b, 7c).

Key words•Pluripotent•Differentiate•Embryonic stem cells

•Oocyte•Blastocyst•Degenerative disease

•Therapeutic cloning

•Reproductive cloning

•eugenics

Stem Cells• All cells start of with the same

DNA, so why do they end up looking so different?

• Some genes “switch on” while others “switch off”, leading to a process called differentiation.

• Cells that have differentiated cells lose their ability to divide and produce more cells of different kinds.

Stem Cells• What happens to cells that

remain undifferentiated?

• These undifferentiated cells are called stem cells – they have the ability to become any other cell in the body (or more stem cells).

• Why is this useful?

Obtaining stem cells - embryos• Most useful at a few days

old – ball of undifferentiated cells.

• Cells at this stage are totipotent – divide to form a whole new organism!

• 50-100 cell stage is described as pluripotent – ability to become any cell type, but not a new organism because some cell differentiation has already started.

Obtaining embryonic stem cells

• Left over blastocysts from IVF can be donated for stem cell research

• Cloned embryos are harvested for stem cells.

• Embryos are destroyed before 14 days old and not allowed to develop any larger than a pin head.

Embryo formation

• Embryo is formed by transferring DNA from embryonic stem cells to an egg whose nucleus has been removed.

• Reconstructed egg containing DNA from a donor cell is treated with an electric current to stimulate cell division and blastocyst formation.

Why are embryonic stem cells needed?

• Degenerative diseases– Alzheimer’s disease– Parkinson’s disease– Spinal cord injury– Stroke etc– Using patients DNA therapeutically to create healthy

stem cells to replace damaged ones.

• Organ transplant– Demand outweighs supply

Why are embryonic stem cells needed?

• “Designer” babies– Produce healthy babies with alleles that are selected to avoid genetic

diseases– Allows for the best combination of genes to be put into making the

new baby– Decrease risk of illness / occurrence of mutant alleles

• Used to test new drugs– Safe testing on differentiated cells generated from embryonic stem

cells– Already use cancer cell lines to treat potential anti-tumour drugs

Ethical issues in cloning and transplant

• Therapeutic cloning• Used in fighting disease, battling infertility, preserving

endangered species

• Reproductive cloning– Made illegal in 2001 for purpose of making a baby– Fear of eugenics – offspring bread to suit social preferences

e.g. looks, memory, intelligence, athletic ability– Moral implications – who gets the technology? The rich?

Ethical issues in transplant surgery• Suggestions that prisoners, homeless and brain-damaged individuals used

as potential donors has been rejected

• BUT could this be a good way to get round the issue of supply and demand of organ donation?

• Transplants from cadavers is considered acceptable (drawbacks last lesson)

• Using “brain dead” patients or those on ventilators requires more thought– Coma patients – are they dead? Can we harvest their organs?– Brain-stem patients on life-support machines are considered (these patients are NOT

alive – they are kept alive by artificial means)

Useful links

• How stem cells are made

• Ethical issues