You can certainly use genes from one animal and insert into another animal. But, we are not quite at the stage of creating hybrids (something that is half one animal, and half another) through genetic engineering. People have tried to create these sort of animals through breeding for many years however, a mule is made from a parent donkey and a parent horse. Such hybrids are often infertile and can’t have their own offspring. It is a good question though, it raises all sorts of ethical considerations in this sort of research.
No. We have a certain number of chromosomes and genes. This is very specific to us. If you mix a sperm from a human with an egg from another animal, they would not be able to mix to form another animal. In fact this is the definition most biologists use for what a species is- if two different types of animals cannot reproduce, they are a different species.
In the lab we can mix genes from what is known as a plasmid, a small ring of DNA, into bacterial cells. We can put genes in to these cells using viruses to transmit the DNA. In this way we can get bacterial cells to produce things we need, like insulin for diabetics.
It is possible to form an organism through the combination of gametes from different species in a lab. Gametes are the reproductive cells- sperm and egg. In 1984 a ‘geep’ (pronounced like geek) was produced by fusing the gametes from a goat and sheep! This is known as a chimeric organism (after the ancient Greek Chimera- half lion/half snake I think but this could be wrong!) and there are other ways to form chimeras too. Also in 2003- scientists managed to fuse human skin cells with dead rabbit cells to form chimeric human embryos that had rabbit genes in them. These embryos were only allowed to develop for a few days and the scientists harvested the stem cells in the embryos to do other research on them. So you can create half- human half animal embryos but we will (hopefully) never know what sort of organisms they would grow into- you would have two very different modes of growth and development competing with each other and this could potentially kill the growing organism. It would also cause a lot of suffering if an organism like that was created in a lab and allowed to grow into an adult- can you imagine! It’s highly unlikely that would happen though since organisms follow strict blueprints when they’re developing from embryos and these blueprints are provided by their genes! If you mix two sets of genes you mix two sets of blueprints and this would probably not work. However, if you just want a very early stage embryo which is just a ball of cells then you could do this providing your research was really important and justifiable.