(August 2004) Genetics and sex determination Genetics is defined as the study of genes. Genes are composed of deoxyribonucleic acid (DNA) that can be passed down and inherited from one generation to the next. The information encoded in DNA is critical for determining the properties of a species1. DNA is divided into discrete molecules called chromosomes, each of which contain numerous genes. Figure 1. Non-disjunction during meiosis II results in two normal gametes, one n+1 gamete, and one n-1 gamete. A ‘normal’ human cell is diploid (2n) because it contains 2 copies of each of the 23 chromosomes. Included in…

(August 2005) DNA is the genetic code of life, a sort of molecular instruction manual that is passed on from mother to daughter cell. This set of instructions is read by the cell and translated into proteins, which perform specific functions within the cell. The DNA molecule itself is made up of a linear sequence of four deoxyribo-nucleotides: adenine (A), guanine (G), cysteine (C) and thymine (T), which form the alphabet of genetic information. The sequence of this linear code leads to the synthesis of proteins through the cellular processes of transcription and translation. To give you a general picture…

(August 2004) It has been 15 years now that the Cre/lox system has been used as a way to artificially control gene expression. If your radar hasn’t picked it up yet, you’re missing out on a clever way to move pieces of DNA around in a cell. Over the years, this system has allowed researchers to create a variety of genetically modified animals and plants with the gene of their choice being externally regulated [1]. This has contributed to our understanding of how individual genes and proteins work. How it works The system begins with the cre gene, short for…

(August 2004) It has been 15 years now that the Cre/lox system has been used as a way to artificially control gene expression. If your radar hasn’t picked it up yet, you’re missing out on a clever way to move pieces of DNA around in a cell. Over the years, this system has allowed researchers to create a variety of genetically modified animals and plants with the gene of their choice being externally regulated [1]. This has contributed to our understanding of how individual genes and proteins work. How it works The system begins with the cre gene, short for…

(August 2004) Deoxyribonucleic acid (DNA) is the fundamental building component of all living cells. Our characteristics, traits and physical features are determined by the specific arrangement of DNA base-pair sequences in the cell. It is this distinct arrangement of adenine, guanine, thymine and cytosine (called DNA nucleotides) that regulates the production of specific proteins and enzymes via the Central Dogma Theory [1]. In a living system, this DNA arrangement is uniform throughout the organism, irrespective of the organ. If the DNA from the hair, organs or any body fluid such as blood, saliva or semen, of a particular organism were…

Picture a group of scientists exploring tropical forests to collect plants, fungi or microorganism samples. They are bioprospecting. In other words, they are looking for new compounds that may help remediate so-far incurable diseases. Picture them settling in villages and discussing with the shaman to learn their traditional way of using plants to heal their people. These local medicine men are often rich of a secular oral tradition about nature’s secrets. Now, picture the scientists coming back to their wealthy country with their suitcase full of unexplored drug candidates. Ten years later, after intense research work and numerous trial and…

(August, 2004) Seeing a cell is an essential aspect of cell biology. To the small world of the cell, confocal microscopy is a major advance upon normal light microscopy since it allows one to visualize not only deep into cells and tissues, but to also create images in three dimensions [1]. There are many aspects to a confocal microscope that make it a much more versatile instrument than a conventional fluorescence microscope. Although the confocal microscope is often thought of as an instrument that can create 3D images of live cells, the great versatility of the machines means that many…

(August, 2003) Flow cytometry is a technology that allows a single cell to be measured for a variety of characteristics, determined by looking at how they flow in liquid [1]. Instruments used for this can gather information about cells by measuring visible and fluorescent light emissions, allowing cell sorting based on physical, biochemical and antigenic traits. Flow Cytometers A flow cytometer, sometimes called a Fluorescence Activated Cell Sorter (FACS), has several key components [2] (see Figure 1): 1. A light or excitation source, typically a laser that emits light at a particular wavelength; 2. A liquid flow that moves the…

It is estimated that nearly 194 million people worldwide have diabetes. This is an increase from the 1995 global estimation of 135 million which was published in a World Health Organization study in 1998[1]. The International Diabetes Federation reconfirms that type 2 diabetes, which is the non-insulin dependent type, constitutes about 85% to 95% of all diabetes cases in developed nations and accounts for an even higher percentage in developing nations. Diabetes continues to affect increasing numbers of people around the world while public awareness remains low. Figure 1. The importance of Islet Amyloid What is type 2 diabetes? Type…