Search results

Mutations A mutation is a change in a gene. It involves some change in the base sequence of the DNA composing the gene. It can be a substitution of one or more bases for others, deletion (omission) of bases or insertion (addition) of bases. If the mutation takes place in an essential part of...

Darwin's 'dangerous' idea The impact of Darwin's theory of natural selection went far beyond science and biology. Darwin's theory of evolution brought to head the clash between science and religion. For centuries studies of religion, theology, philosophy, the arts and science had been...

Haemoglobin and oxygen levels The city of La Paz in Bolivia is a city with one of the highest altitudes in the world. Some poeple who visit La Paz find it very difficult to breathe especially if they exercise. Newcomers to La Paz are recommended to move slowly at first to acclimatise themselves...

Diseases and cleanliness TRANSMISSION Disease pathogens can be transferred from one individual to another in a number of ways - by air, water, food, contact and vectors. Air is continuously moving around due to temperature changes and air currents. It contains gases, water vapour, microbes...

Stages of gene expression There are a number of stages at which gene expression can be controlled in eucaryotic cells. While transcription is an important stage, it is not the only one. STAGE ONE - UNPACKING - DNA is bundled or wound around protiens called histones to form structures...

Amount of Substrate When we did this pract our teacher told us that the smount of substrate does not matter as long as it is kept constant in all test tubes and is balanced with whatever else you a putting in. e.g. you can put 10ml of sugar in a test tube and expect it to dissolve in 2ml of...

Cell differentiation Cell Differentiantion - Most multicellular plants and animals begin their existance as a single cell. In multicellular organisms, this cell undergoes a long sequence of changes, which eventually provides all the different tissues and organs. All cells in an organism...