Muscle contraction is a tricky bit of A-Level biology. There are lots of new terms to learn and a complex process to get your head around. Make sure to review it regularly so that it sticks in your brain. Before beginning this article, make sure you are happy with the different parts of a muscle... Continue Reading →
Muscle Fibre Cells – Muscles Ep 1
Muscle fibre cells are a great example of how animal cells can be highly specialised for their function. In this article we will look at the structure of muscle fibre cells and how it relates to their function. Muscle fibres cells - structure and function The below diagram shows a cross-section of a muscle fibre... Continue Reading →
Cystic Fibrosis – Diseases Ep 3
Cystic fibrosis is an inherited disorder affecting specific channel proteins in cell membranes. In this article we will look at how it is inherited, how chloride ion transport is affected, and the symptoms which develop as a consequence. Inheritance of cystic fibrosis Cystic fibrosis is an inherited recessive disorder, meaning it is caused by a... Continue Reading →
Biochemical Tests – Practical Skills Ep 2
In A-Level biology, there are four biochemical tests to learn for four different biological molecules. This article gives full details of the tests, and a helpful colour summary at the bottom. Test for reducing and non-reducing sugars A sugar is a monosaccharide or disaccharide. The vast majority of sugars learnt about in A-Level biology (glucose,... Continue Reading →
Mutations – Variation and Biodiversity Ep 1
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... Continue Reading →
Antibodies – Immunity Ep 4
Antibodies are very important proteins in the immune response. We've already mentioned them a lot in the last few articles but today we will take a detailed look at their structure and function, and how they can be used in medical applications. Antibody structure Antibodies are proteins with a quaternary structure. They have two longer... Continue Reading →
Coenzymes and Cofactors – Enzymes Ep 4
So far in this series we have looked at how enzymes work, what can affect the rate at which they work, and how their action can be inhibited. Today we are looking at coenzymes and cofactors: non-proteins that are needed in order for some enzymes to be able to catalyse their reaction. Coenzymes Coenzymes are... Continue Reading →
Enzyme Inhibition – Enzymes Ep 3
An enzyme inhibitor is a molecule that binds to an enzyme and prevents it from catalysing a reaction. In this article we will look at two types of enzyme inhibition - competitive and non-competitive inhibition. Although enzyme inhibitors can sometimes have devastating consequences, some of them are actually quite important. We will look at some... Continue Reading →
Factors Affecting Enzyme Activity – Enzymes Ep 2
In the last article we looked at how enzymes work as biological catalysts. However, there are various factors affecting enzyme activity, and consequently the rate of the reactions they catalyse. Today we will look at the four main factors that influence the rate of enzyme activity. Substrate concentration This one makes quite good sense. If... Continue Reading →
Enzyme Basics – Enzymes Ep 1
You know when you look at a word too much and it starts to look weird? That will definitely happen with the word 'enzyme' as we move through this topic. Today we're going to take a look at the basics of what enzymes are and how they act. What are enzymes? Perhaps the first phrase... Continue Reading →
