Muscle contraction requires a large amount of ATP, meaning that a constant source of ATP is needed. In this article we will look at the three sources of ATP which muscle fibre cells can use. Phosphocreatine ATP has to be made by adding a phosphate group (Pi) to ADP. In the ATP-phosphocreatine system, the phosphate... Continue Reading →
Muscle Contraction – Muscles Ep 2
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. Before beginning this article, make sure you are happy with the different parts of a muscle fibre cell. Sarcomeres Myofibrils are made up of two main protein filaments: actin... Continue Reading →
Light-Independent Reaction – Photosynthesis Ep 2
In the last article we left photosynthesis at a point where ATP, reduced NADP, and oxygen had been produced in the light-dependent reaction. Oxygen is a waste product of photosynthesis, however the ATP and reduced NADP are used for the light-independent reaction. So although light energy isn't specifically needed for any reaction in this next... Continue Reading →
Light-Dependent Reaction – Photosynthesis Ep 1
Photosynthesis is the process used by plants and other photosynthetic organisms to produce glucose. The glucose can then go on to be used in respiration, stored as starch, or used for other purposes. Photosynthesis requires light energy, but it is actually only the first stage which is directly light-dependent. We will focus on the light-dependent... Continue Reading →
Anaerobic Respiration and Respiratory Quotients – Respiration Ep 4
Anaerobic respiration happens when there isn't enough oxygen present for aerobic respiration to continue. Different types of organism use different pathways. For both pathways we will learn about today, the yield of ATP is much lower than in aerobic respiration because the only ATP produced comes from glycolysis (2ATP per glucose molecule). In this article... Continue Reading →
Oxidative Phosphorylation – Respiration Ep 3
We've reached the final stage of aerobic respiration - oxidative phosphorylation. This step takes place using proteins in the inner mitochondrial membrane. Now we will find out what all the reduced NAD and reduced FAD produced in glycolysis, the link reaction, and the Krebs cycle is used for. Oxidative phosphorylation The coenzymes NAD and FAD... Continue Reading →
The Krebs Cycle – Respiration Ep 2
The Krebs cycle has many names. Sometimes it is called the tricarboxylic acid (TCA) cycle or the citric acid cycle. But whatever name you give it, it's an important part of aerobic respiration. In the last article we covered the first two stages of aerobic respiration (glycolysis and the link reaction). We ended the link... Continue Reading →
Glycolysis and The Link Reaction – Respiration Ep 1
In this series we are going to be looking at respiration. This is the process that releases energy from glucose to produce ATP. In the first few articles we'll be focusing on aerobic respiration (which uses oxygen) and then we will cover anaerobic respiration (which doesn't use oxygen) in the last article. Please bear in... Continue Reading →
Active Transport – Exchange and Transport Ep 4
So far we have looked at the passive movement of substances across cell membranes by diffusion and osmosis. Sometimes substances need to move against a concentration gradient, which is when active transport comes into action. Active transport Active transport uses energy from ATP to transport substances from an area of lower concentration to an area... Continue Reading →
ATP – Biological Molecules Ep 5
Today we are looking at adenosine triphosphate, often just abbreviated to ATP because as with most scientific terms, it's a bit of a mouthful. This molecule is very important in providing an immediate source of energy for processes in cells. Let's have a closer look at its structure and function. Structure of ATP ATP is... Continue Reading →
