HIV (human immunodeficiency virus) is a virus which can eventually lead to development of AIDS (acquired immunodeficiency syndrome). However, it is not the virus itself which causes AIDS symptoms; HIV weakens the immune system, meaning other infections can take hold more easily. In this article we will look at HIV structure, replication, and development of … Read more
Electrophoresis is a method used to separate fragments of DNA or RNA based on their size (length*) using an electric current. It has applications in processes such as genetic fingerprinting and disease diagnosis. DNA and RNA are negatively charged which means they will move towards a positive electrode. This technique can be used for proteins, … Read more
So far in the genetic engineering journey we have learnt how to isolate or produce a DNA fragment, and amplify it in vitro using PCR. Bacterial transformation is a method to amplify a DNA fragment in vivo (in a living organism), and to engineer bacteria to produce a protein. In this article we will look … Read more
Once a DNA fragment has been isolated or produced (see the last article), the next step is often to produce many copies of it. One common way to do this is to use the polymerase chain reaction, which is a fairly simple process that can be automated. In this article we will look in detail … Read more
This article begins a new series about gene technologies. Many gene technologies, especially recombinant DNA technologies, begin with the need to isolate or make DNA fragments. We will look at three different ways that this can be achieved. Restriction enzymes This method allows DNA fragments to be "cut out" of existing DNA. Restriction enzymes, sometimes … Read more
There is a huge variety of life on this planet. In this series we will look at how all that variation exists, from the DNA level to the population level. Today we are starting off with a source of variation at the DNA level. What are mutations? A genetic mutation occurs when the DNA base … Read more
Meiosis is a little more complicated than mitosis, and has a different outcome. Meiosis is a method of cell division which only happens in the reproductive organs of organisms which reproduce by sexual reproduction. It produces genetically different gametes with half the number of chromosomes as the parent cell. These gametes (the egg cells and … Read more
In the last article we looked at mitosis as a method of cell division. However, mitosis can only take place in eukaryotic cells. Prokaryotic cells such as bacteria, which don't have a nucleus, divide by binary fission. This process produces two genetically identical daughter cells from the parent cell, and is a method of asexual … Read more
Mitosis is a method of cell division used by multicellular organisms for growth and repair of tissues. Some plants and fungi (and rarely some animals) also use it for asexual reproduction - producing genetically identical offspring from one parent. Mitosis results in two daughter cells which are genetically identical to the parent cell. In this … Read more
All the cells in multicellular organisms which are capable of division go through a cell cycle - a sequence of phases which incorporates cell growth, DNA replication, and cell division by mitosis. However, remember that not all cells are capable of division e.g. red blood cells. The Cell Cycle The cell cycle begins just after … Read more
