17th February 2022
A-Level Biology is an entry requirement for many Medical Schools, along with Chemistry, but which parts of the A-Level syllabus will be the most helpful when you’re at university? In this blog, Kirsty shares how she is using her A-Level Biology knowledge at Med School, so you can prepare yourself and know what to expect.

I studied the Edexcel syllabus for my Biology A-Level, and this gave me an excellent foundation in many scientific principles. Here are just some of the ways that my A-Level Biology knowledge has been put to good use while I’ve been studying Medicine so far.

Biological Molecules – The Gastrointestinal System

When I began to study the gastrointestinal system at Med School, I was surprised by how many fundamentals had been covered as part of my Biology A-Level. I already had a good understanding of the molecular structure of proteins, carbohydrates and lipids, and how they could be formed and broken down via condensation reactions and hydrolysis respectively. This aided my understanding of chemical digestion throughout the GI tract and of how each nutrient is broken down into its constituent monomers and absorbed.

My A-Level knowledge of enzymes proved particularly helpful in understanding the concept of an active site and a complementary region of the substrate, as well as the effect of temperature and pH on the rate of enzymes, and explaining why different nutrients undergo digestion at different regions of the GIT. An interesting fact from A-Level Biology relates to the production and release of peptidases from the stomach – how can these enzymes be released without digesting themselves? (A-Level Biology teaches us that enzymes are in fact proteins themselves!)

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DNA And Cell Division – Molecular Basis Of Chromosomal Abnormality

It was part of my A-Level Biology syllabus to learn about the DNA replication process, plus mitosis and meiosis. Following on from this, something I found particularly interesting in my first year of Med School was the genetic causes of Down Syndrome (trisomy 21).

At A-Level, I was taught about meiosis and the separation of the sister chromatids into their daughter cells during the second round of division in meiosis. If there is a segregation error, there may be two of the same chromosomes in one daughter cell (aneuploidy). And if this gamete is fertilised, this may lead to a trisomy such as trisomy 21, or Down’s Syndrome. This is one reason why trisomy might occur. However, at Med School we have also learned about a different molecular basis for Down’s Syndrome – chromosomal translocation and how this can cause partial trisomy, giving rise to the condition.

Movement In And Out Of Cells – Pathology

In A-Level Biology, I learned about different types of movement in and out of cells, such as active transport and facilitated diffusion. I was also taught about different types of channel and carrier protein, which aid movement across the cell membrane.

At Med School, we have learned about how various abnormalities in these transport proteins (i.e. genetic mutations resulting in a non-functional protein) may give rise to different types of pathology. For example, we can consider type 2 diabetes and resistance to insulin, and therefore the lack of GLUT-4 channels which are important for the transport of glucose from the blood into cells. We can also consider cystic fibrosis and a genetic mutation which gives rise to a non-functional membrane protein and chloride channel (CFTR). This means that there is abnormal salt transport by epithelial cells, resulting in thick, sticky secretions. Finally we can consider the ion channels involved in the action potentials of the heart, and how a mutation in a potassium or a calcium channel may affect the contractile activity of the heart and give rise to an arrythmia.

Statistics And Their Use In Evidence-Based Medicine

Although it can be tricky to get your head around the P test, statistical significance and the null hypothesis, this A-Level Biology knowledge really helped me at Med School when we were considering study design and evidence-based Medicine.

It can help you to differentiate between a current and an alternative therapy, and to see if an alternative therapy should be integrated into clinical practice if it will promote a better therapeutic outcome for patients. It can also enable you to consider the accuracy of a study and determine if it is trying to hoodwink its readers – e.g. if the results are approaching statistical significance, when what this really means is the results have not shown significant difference between two given interventions. An understanding of basic statistical tests has helped me to understand the concept of the type I and the type II error. In other words, rejecting the null hypothesis when it is true and rejecting the null hypothesis when it is false respectively. To sum up, A-Level Biology has enabled me to be more critical when reading scientific papers.

Drug Receptor Interactions/ Pharmacology

Finally, my knowledge gained from A-Level Biology has helped me with my understanding of pharmacology. At A-Level, I learned about different binding regions when considering the enzyme and its substrate (the active site of the enzyme), as well as complementary and non-complementary regions of the substrate. We also considered competitive and non-competitive inhibition.

At Med School, we have studied drugs which can be considered as antagonists and agonists, depending on whether they inhibit or stimulate a given pathway respectively. I have found it interesting to explore competitive inhibition and non-competitive inhibition between these two types of drug, and to consider what the overall effect will be on the patient (e.g. the effects on the sympathetic nervous system of the patient). It has also been fascinating to think about competitive inhibition, and how this may lead to certain drug/drug interactions and toxicity associated with certain drugs.

Check out this guide to surviving your first year of Med School to discover what else you can expect to face as a new Med student – including dissection, patient interaction, and your first exams.

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