Cloning

A clone is an organism that is genetically identical to its parent. We can say that daughter cells form mitosis are clones because they are genetically identical to their parent cell. We can also say that daughter cells from meiosis are not clones because they are not genetically identical to their parent cells.

We do not clone humans because we don't know the effects and there are many ethical considerations which currently outweigh the possibilities. However, we can clone plants in a number of ways for many reasons. It is also not unheard of to clone animals like cows and chickens for products and specific advantageous characteristics.

Plant cloning can be done in a number of ways. One method involves taking cuttings of plants. A plant can be easily cloned by taking a cutting from the shoot tips, areas around the leaves and from the root tips (we use these areas because that's where the unspecialised meristem cells are to grow into a new plant). Next, we dip the cuttings in rooting powder and plant them in nutrient soil. It's important to know that we can't produce too many of these as it would cause significant harm to the original plant.

 (chuttersnap)

Alternatively, we can use another method of cloning. We can, again, take samples from the root tips, shoot tips or areas around the leaves. Next the tissues are taken off and separated into cells. The cell walls are removed and the wall-less cells are places into nutrient rich agar jelly. The jelly provides everything the cells need to grow and divide such as hormones. We can use this method on a larger scale than the first method as we only need a few cells to produce whole plants- though how expensive is it to remove a tiny cell's cell wall?

Similarly, we can clone animal embryos for specific purposes. A frequently used example includes the cloning of cow embryos. A normal cow produces 8-10 calves during her normal working life however using embryo cloning, she can produce more calves than that in a single year! Using cloned embryos allows high quality embryos to be transported all around the world - which is particularly useful for cows with high milk/strong meat yields. But how do we clone the embryos in the first place?

 Enjoy these chunky country cows (Luca Basili)

1. A cow with the desired characteristics is fed hormones to allow her to produce an egg cell. This egg cell is collected
2. Sperm from bull (could have desired characteristics) is collected and the egg is artificially fertilised (in a lab)
3. The fertilised egg starts to divide into an embryo (mitosis). Four unspecialised egg cells are removed from the embryo 
4. The four unspecialised cells develop into their own embryos. These new embryos are implanted into four host mothers. 
5. The four host mothers give birth to four genetically identical clones

The four calves are genetically identical because they are made up of the same DNA of the original parents. The host (surrogate) mother cos that gave birth to them have nothing to do with the genetics.

We can also look at the cloning of sheep to create a clone of the parent sheep:

1.  DNA is extracted from sheep 1
2. The nucleus is removed from sheep 2's egg cell
3. The DNA from sheep 1 is fused with sheep 2's egg cell
4. The fused cell develops into an embryo which is place into surrogate sheep 3
5. A lamb is born as a clone of sheep 1

I( Jorgen Haland)

As previously mentioned, cloning also ties in with many ethical considerations. We have to weigh up the advantages and disadvantages;

• We can use cloning in regenerative medicine e.g growing new organs, skin grafts PRO
• Overcomes the shortages in organ donors- grow the organs PRO
• Help in research PRO
• Reproductive cloning allows infertile couples to reproduce PRO
• An embryo is not a human PRO
• Old age can be combatted, increases life expectancy PRO
• It's against man religious teachings CON
• Meat from cloning could be unsafe for human consumption CON
• It's a relatively new process so could have unseen circumstances and impacts CON
• Confuses animal kinship (eg who is my cow mum?) CON
• Destroying embryos could be seen as equivalent to killing  twin, sibling CON 

(Keisha Monfleury)