Cloning

The first human being has been cloned!

What would be your view on this if it happened?

Keyword Meaning Clone Changing the genetic

characteristics of an organism by manipulating genes and

introducing them into DNA.

Genetic Modification

In this technique, the nucleus from a body cell of the adult is removed and

implanted into an egg cell that has had the nucleus removed.

Nuclear Transfer

A genetic copy of another single organism, or group of cells

Inheritance A term used to describe the passing of genes from parents to offspring

1. Inheritance

A term used to describe the passing of genes from parents to

offspring.

2. Genetic ModificationChanging the genetic characteristics of an

organism by manipulating genes and introducing them

into DNA.

3. CloneA genetic copy of another

single organism, or group of cells

4. Nuclear TransferMost common method of artificial

cloning. In this technique, the nucleus from a body cell of the adult is removed and implanted into an egg cell that

has had the nucleus removed.

Cloning a single adult animal, especially a mammal, is very complicated.

The most famous animal clone is Dolly the sheep, who was born on 5 July 1996.

Dolly was not the first animal clone, but the first mammal to be cloned from an adult cell.

What is nuclear transfer?Dolly was created using a technique called nuclear transfer.

The egg cell is then made to divide and develop like a normal fertilized egg. The important difference is that it only contains the DNA from one, rather than two, animals.

In this technique, the nucleus (i.e. DNA) from a body cell of the adult is removed.

This nucleus is then inserted into an egg cell that has had its own nucleus removed.

Cloning has Many Uses

1. Could help with the shortage of organs for transplants.

2. Study of animal clones could lead to greater understanding of the development of the embryo and of ageing.

3. Preserve endangered species.

Issues Surrounding Cloning

Cloning mammals leads to a ‘reduced gene pool’- this means there are fewer different alleles in a population.

• If populations are all closely related and a new disease appears, they could all be wiped out-because there may be no allele in the population giving resistance to the disease.

Issues Surrounding Cloning...

Cloned mammals mightn’t live as long- Dolly the sheep only lived for 6 years

• She was put down because she had lung disease and she also had arthritis, these diseases were more usual in older sheep.

• Dolly was cloned from an older sheep, so its been suggested her ‘true age’ may have been older.

• But its possible she was just unlucky- and that her illnesses weren’t linked to her being a clone.

Issues Surrounding Cloning...

There are other risks and problems associated with cloning

• The cloning process often fails. It took hundreds of attempts to clone Dolly.

• Clones are often born with genetic defects.

• Cloned mammals immune systems are sometimes unhealthy- so they suffer from more disease.

Stem Cells

Quick Questions

1.In terms of cells what do specialised and differentiation mean?

2.Name one type of specialised cell and how it is adapted to do its job?

stem cells can differentiate into any type

of cell

1. In terms of cells what do specialised and differentiation mean?

Specialised – Cells that have special characteristics to

allow them to do their job.

Differentiation – In cells, the process whereby new cells

develop special characteristics to allow them to do their job.

2. Name one type of specialised cell

• Red Blood Cell - No nucleus, large surface area.

• Sperm Cell - Pointy head, tail, enzymes in the cytoplasm.

• Root hair cell - Large surface area, thin membrane.

What are stem cells?The first cells are stem cells. These are unspecialized cells capable of developing into many different types of cell.

If stem cells continued to divide as they were, humans would end up as a large jelly-like blob!

Stem cells found in embryos are called embryonic stem cells and develop into all the different types of cell in the body.

When the embryo contains about 500 cells, the cells stop being the same and they stop getting smaller with each division. They start to differentiate into different types of cell.

stem cell

tissue cellstem cell

Tissue cells continue to divide and differentiate, each time becoming more and more specialized.

Some will become nerve cells, others will become blood cells, muscle cells, bone cells, etc.

nerve cells red bloodcells

stem cell

tissue cells

cardiac musclecells

Stem Cells May be Able to cure Many diseases