A-Level Biology & Chemistry and GCSE Science Tuition. A-Level Biology Revision.
Control of blood glucose is very important. Sufficient glucose must be delivered to cells for respiration, but too much glucose can eventually result in coma or even death. The concentration of glucose is affected by factors such as eating and exercise, and must be brought back to the normal level of about 4mmol/L to 5.5mmol/L.... Continue Reading →
Homeostasis is the maintenance of a stable internal environment. The conditions inside the body must be stable so that cells can function properly. For example, if the temperature or pH are too high, enzymes can become denatured. It is also important to maintain blood glucose concentration and water potential, which we will look at in... Continue Reading →
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... Continue Reading →
The environmental conditions must be just right for photosynthesis to take place at the fastest possible rate. Today we're going to take a look at how light intensity, temperature and carbon dioxide (CO2) concentration can affect and limit the rate of photosynthesis. They will also affect plant growth, because photosynthesis produces glucose for respiration. Plants... Continue Reading →
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 →
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 →
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 →
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 →
So far in the exchange and transport series we have mainly been looking at exchange and transport of gases. However, organisms also need to absorb nutrients such as glucose and amino acids so they can carry out processes like respiration and protein synthesis. In this article we will cover how large food molecules are broken... Continue Reading →
We've already looked at the monomers that make up a protein: amino acids. But fully functioning 3D proteins are much more complex in structure than a simple polypeptide chain. Today we will look at the different levels of structure in proteins and some specific examples. Levels of protein structure So let's start with a quick... Continue Reading →
