(August 2003) The separation of DNA/RNA fragments or a protein sample based on size can be useful in many applications, but visualizing samples on a gel does not give any information about the identity of the sample (i.e. which gene fragment, mRNA or protein you are looking at). So how can you pick out the band you’re interested in? E.M. Southern answered this question when he developed a method that was subsequently named after him, the Southern Blot. Figure 1. The layout for a Southern Blot. The Southern Blot takes advantage of the fact that DNA fragments will stick to…

(August 2003) The Polymerase Chain Reaction (PCR) is an important tool for many applications. For example, it can be used to amplify a sample of DNA when there isn’t enough to analyze (e.g. a sample of DNA from a crime scene, archeological samples), as a method of identifying a gene of interest, or to test for disease. The method uses specifically designed primers that are complementary to the sequence to be amplified. The primers provide a starting point for the extension of the DNA by a DNA polymerase (usually Taq or Pfu polymerase). Amplification is carried out in cycles. First,…

(August 2004) Intelligence is a very difficult concept to define. Intellect is described as “the power of the mind to think in a logical manner and acquire knowledge” [1]. Even psychology experts have not agreed upon what this actually means [2]. Intelligence can be divided into various subcategories such as reasoning, problem solving, and memory, and so creating a consistent scale by which one can measure intelligence is quite difficult. Figure 1. IQ testing is a widely used measure of g. Many researchers working on intelligence use a psychometric definition for intelligence, termed “general mental ability” or the “g factor”.…

(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…