Presentation on theme: "All you ever wanted to know about cloning but were afraid to ask!"— Presentation transcript:
All you ever wanted to know about cloning but were afraid to ask!
First we need to talk a little about normal reproduction... As you know, HAPLOID gametes are produced by meiosis During fertilization, the sperm cell encounters an egg cell and deposits its chromosomes into the egg The egg cell is now fertilized, has DNA from 2 sources, and is DIPLOID. We call this cell a zygote.
Here are the sperm cells trying to fertilize the egg
A fertilized egg = zygote Notice the nuclei from the egg and sperm fusing
What happens to the zygote? The zygote begins a rapid cell division to divide into a ball of cells called the embryo. This is done by mitosis so all of the cells in the embryo are genetically identical. Within a few days, the middle of the embryo hollows out during the blastocyst stage.
This is what 4 day old embryos look like
5 day old embryo at the blastocyst stage
How big is a blastocyst?
During this time, the embryo is moving from the site of fertilization (in the fallopian tube) to the uterus where it will implant and continue its development.
Heres where the process happens in the female system
That takes care of natural reproduction but how exactly is something cloned?
Cloning The term clone simply means two things with identical DNA (ie. identical twins) When we try to clone organisms (this is called reproductive cloning) we need to take the diversity out of reproduction. Instead of using two sources of DNA (the egg and sperm), we use one source of DNA. Cloning sounds easy but it is actually quite difficult
How to clone something To clone an organism, there are 5 steps involved. 1.Take an egg cell 2.Remove the DNA from the egg cell so that it is empty 3.Take a diploid cell from what you want to clone. Add the diploid DNA to the empty egg 4.Let the cell divide into an embryo 5.Implant the embryo into the uterus of a surrogate mother to finish development Note: the clone will be genetically identical to the diploid cell that was used in the procedure.
How to clone most anything in 5 easy steps!
Now you have the basics so lets move on to the history and some ethical issues
Reproductive Cloning Or, Ewe?
Ra a leader of the Raelian Movement, the world's largest UFO-related organization numbering 60,000 members in almost 100 countries, founded Clonaid, the first company offering to clone human beings. In 2003, Clonaid announced that they had cloned the first human named Eve. Well, according to Clonaid,…..YOU!
Of course everyone from the Vatican to the US government to biotechnology companies criticized the alleged cloning. Proof has yet to be provided on this claim and no genetic testing on this alleged baby has ever been done.
Is it illegal to clone a human?
THE PRESIDENT'S COUNCIL ON BIOETHICS Washington, D.C. July 10, 2002 The Council holds unanimously that cloning-to-produce-children is unethical, ought not to be attempted, and should be indefinitely banned by federal law, regardless of who performs the act or whether federal funds are involved.
There are no United States federal laws against cloning. In 2001 the House of Representatives passed a bill to ban both reproductive and research cloning, which President Bush indicated he would sign. The Senate tabled the legislation and a vote was never taken. Why is it that the US, unlike many other nations, has not yet been successful in enacting legislation to ban reproductive cloning? The US Food and Drug Administration (FDA) has claimed jurisdiction over human cloning, but is mandated by law to consider only safety and efficacy, and not to consider social, political, or moral issues.
State human cloning laws Fifteen states have laws pertaining to human cloning. The issue was first addressed by California legislature, which banned reproductive cloning, or cloning to initiate a pregnancy, in Since then Arkansas, Connecticut, Indiana, Iowa, Maryland, Massachusetts, Michigan, Rhode Island, New Jersey, North Dakota, South Dakota, and Virginia have enacted measures to prohibit reproductive cloning. By NJ law: violators who are found guilty could receive a prison sentence of up to 20 years!
Some common points of discussion on cloning humans
Concern: Cloners might bring back horrible people from history, like Hitler. The clone would have the same genes as Hitler and therefore, look like Hitler…but he would not behave like Hitler. We also know in utero development and environment play a major role in who a person is and how they behave! Genes code proteins, not memories or souls. – Ronald Bailey
Concern: Having a clone of oneself would lessen ones own uniqueness as an individual. The President's Council on Bioethics expresses this as: Our genetic uniqueness is an important source of our sense of who we are and how we regard ourselves. It is an emblem of independence and individuality. It endows us with a sense of life as a never-before-enacted- possibility…we go forward as genetically unique individuals into relatively indeterminate futures.
But, do identical twins suffer from a badly impaired sense of individuality and identity? Genetic essentialism is a term coined by a bioethicist at UVA. This is the idea that our genes completely determine who we are (approx % of polled Americans feel this way.) Or that the human genome is equated with the essence of the human.
And, we also know that maternal factors in each egg and differences in the womb between the original vs. surrogate mother can influence development. Therefore, a clone is not carbon copy! Lets take a look at a human egg… proteins RNA (mitochondria have their own DNA and so all your mitochondrial DNA came from your mother only!)
Concern: Children should be brought into the world naturally and not in this unnatural manner. There are many reasons and in many ways that individuals decide to bring a child into their family. Children are born into all kinds of situations. Just because the child wasnt a fruit of the embrace doesnt mean they are unnatural or unwanted. This generic argument may start down a slippery slope of what types or manners of reproduction, or having a child, are acceptable. Presidents Council on Bioethics states, procreation is not making but the outgrowth of doing. A man and a woman give themselves in love to each other, setting aside their projects to do just that. Yet a child results, arriving on its own, mysterious, independent, yet fruit of the embrace.
Concern: Clones will be made for the purpose of spare parts (to prevent immune rejection). Senator Christopher Bond (R-MO) stated, The creation of human beings should not be for spare parts or as a replacement. Most everyone would agree with Senator Bond; not likely much disagreement there. The U.S. has recently passed a fetal farming bill that prohibits this too. Remember, even if cloning in humans were successful we dont know if this type of production for spare parts would be. More to come on this when we discuss therapeutic cloning.
Concern: Sexual reproduction creates genetic diversity for the purpose of staying ahead of ever-mutating pathogens. Diversity in a population is good. True. Genetic diversity is good. This is a concern with cloned plants and animals used in agriculture in which they are all identical. But, hypothetically, if all of those in one neighborhood decided they must clone a human, would they all choose to clone the same person? No. Therefore some diversity remains.
Lets absurdly imagine that there were millions of clones of one person. Was it genetic diversity that allowed humans to beat polio, measles, typhoid, and typhus, etc? Nope, it was modern medicine and sanitation. So… if a new pathogen comes along in a slightly less diverse human world…it is likely medicine and technology will win again.
Concern: Scientists will be ready to forge ahead with reproductive cloning as soon as they can perform the task technically. Well, we know we can do it technically with the production of Dolly. But those successes in animals have also shown us it has a high rate of failure and is highly inefficient. That is, it takes many failed embryos to produce one healthy cloned animal. Severe abnormalities can develop in cloned animals too (such as enlarged hearts, defective kidneys, obesity). Only a small percent of clones are long term survivors. Dr. Ryuzo Yanagimachi, University of Hawaii Genetically identical mice: the obese one on the right is the clone.
Should human cloning be banned? If human cloning is banned or made permanently illegal; there may eventually be off- shore cloning yet there would not be standards and safety rules. This obviously would bring up concerns of wellbeing and unsafe cloning. But, if it is not made illegal and technology advances before biological and ethical issues are resolved, there could be a huge impact on our society. Ultimately, you have to make this decision for yourself.
Historically, we find that many a great medical breakthrough, now seen as a blessing, was in its own time ferociously condemned by bio-conservative moralists. This was the case with anesthesia during surgery and childbirth - people argued that it was unnatural and that it would weaken our moral fibers. It was also the case with heart transplantations - how yucky to take a living heart of one person and put it in the chest of another! And it was the case with in vitro fertilization - these "test tube babies" would be dehumanized and would be subject to grave psychological abuse. Now of course, anesthesia is taken for granted, heart transplantation is seen as one of medicine's greatest triumphs, and the public approval rate of IVF is up from 15% in the early seventies to over 70% today. In the big scheme of things, cloning will not significantly change the world. Some people will owe their lives to this technology, and some infertile couples will be grateful for having had the chance to raise a child of their own that they would otherwise have lacked. Some people may misguidedly use cloning to try to bring back a lost child or a loved one, not realizing that personal identity is not reducible to genetic identity. Some people may choose to have a child that is a clone of a stranger they admire, perhaps a great scientist, athlete or religious leader; yet if the current level of demand for elite sperm or elite eggs is any indication, the class of people who will choose to do this will be a tiny minority. Dr. Nick Bostrom; Lecturer, Department of Philosophy, Yale University Another opinion:
Why are scientists interested in cloning animals? To control the selective breeding we are already doing now in dogs To produce pharmaceuticals from the desired protein produced in the milk of such animals. (Researchers have managed to transfer human genes that produce useful proteins into sheep and cows, so that they can produce, for instance, the blood clotting agent factor IX to treat haemophilia) Enhance biodiversity by keeping endangered species numbers up. Xenotransplantation- animal to human transplants
Some animals that have been cloned: Carp Cats Cattle Deer Dog Ferret Frog (tadpole) Fruit Flies Goat Noah (48 h) Horse Mice Mouflon (1 st to live past infancy) Mule Pig Pyrenean Ibex (7 min) Rabbit Rats Rhesus Monkeys Sheep Water Buffalo Wolf
Another source of information: Presidents Council on Bioethics
Materials for this presentation were provided by: Dr. Kelly Hogan, UNC Meredith Norris, UNCC Jennifer Warner, UNCC