Deoxyribosenucleic acid – this is such an important molecule, but do you know why?

Want to know why DNA is important, watch this little video for an introduction.


Now it’s time to study DNA, not just another biological molecule! Well actually it is, but it is very important. It is the molecule that is shared (with just very small variation) by every living organism on the planet – well all the ones we know about anyway. As the instrument of heredity it is well worthy of our study, together with how it replicates itself everytime that you grow a new cell. Now before you start to panic that it is going to be really complicated, ask yourself this question – ‘How complicated can DNA replication actually be if it occurs trillions of times in your  body with very few errors’? While it does seem complicated (especially with the language that we use), DNA is actually a very simple code.

We will shortly  extract DNA from  bananas. If you want to impress your friends and family by doing it at home, here is a delightful video showing you how to extract DNA from strawberries.

First we will look at DNA structure, check out

Then even more presentations from Mr. Taylor – this man is a veritible human dynamo when it comes to IB Bio presentations:

DNA structure

DNA replication

If after the last two lessons you are still struggling to get to grips with DNA replication then check out these summary notes. Can you use them to complete the activity from last class (re-arranging the key words)? DNA replication notes. AHL

Protein synthesis core

Protein synthesis HL

and finally here is a really useful powerpoint produced by Mrs. DickinsonProtein-Synthesis-AHL

Edit This

Anyone need a hand?


Several people have spoken to me about the slideshare we are using to learn about biological molecules, and are struggling to use it effectively. (It’s ok, different resources work for different people).  I am also aware that the SL students are still missing a text book. To help I have some supplementary notes that cover the same information which I have posted here for you Organic Compounds Notes if you dont like the slideshare. Thanks to Gretchen Kitchener for this.

While I am at it here are a few notes that support the additional higher level information you need to know about proteins.Additional HL notes about proteins.  and slide share if you are aiming for a level 6 or 7 I do recommend this slideshare(Topic 7.5), OR you can look at this powerpoint from Mrs. Nadine Dickinson which has the same information (but without polar molecules).Proteins AHL. We will look at these in more detail later – though if the HL students want to get ahead then ……..

In class today I will set you a homework on biological molecules, if you lose the printed version you can access it HERE

You are what you eat, but what do you eat? An investigation into food testing


There are so many questions that we need to be able to answer in this first section, some of which are given below:-

  • Can you distinguish between organic and inorganic compounds?
  • Can you identify carbohydrates, lipids and proteins from diagrams?
  • Can you explain the role of condensation and hydrolysis reactions between amino acids and polypeptides, between mono, di and polysaccharides, and between fatty acids, glycerol and triglycerides?
  • Can you compare the use of carbohydrates and lipids in energy storage?

To get the ball rolling we are going to start off with an investigation into foods by performing some food testing. In this practical Lab-Comparison-of-chemical-composition-of-food you will learn how to test everyday foods for Starch, Reducing sugars, proteins and lipids. This investigation will be another opportunity to practice writing conclusions and evaluations; I am looking forward to seeing which of you are reflective learners, will you learn from your previous mistakes? Look back at your first attempt at writing a conclusion and evaluation. Look also at this exemplar, for Conclusion and evaluation tips Draft Exemplar sa to vol lab, or in windows 2003 format here Draft Exemplar sa to vol lab

Once we have performed the lab we will use another slideshare from Stephen Taylor to learn about the Carbohydrates, Lipids and Proteins

While working through the slideshare some students told me about the following web site This site gives you access to ‘flash card’ type resources for a myriad of subjects, not just Biology. Just search within the site IB Biology (or any other subject that you want) and then find relevant resources. For a content heavy section like Biochemistry this could be very useful. Thanks to the students concerned for bringing it

Goblins, Ghouls, Magic and the Dark Arts; oh and Homeopathy – an investigation into Pseudoscience


Now before you all start shouting at me for being unfair “my mum swears by homeopathic treatments”, I want to ask a question. Is there any evidence to support the hypothesis that water has memory? Is the idea that water somehow ‘remembers’ the molecules it has been in contact with a reasonable one? If you think it is, you should be able to come up with an aim and hypothesis to investigate this idea. Has anyone done this for homeopathic treatments? Is there any evidence available that supports the efficacy of homeopathic treatment, or does the homeopathic industry rely on anecdotal claims to justify it’s existence?

If this sounds like TOK then good, because it is! Remember my favourite saying ‘Without evidence it is just an opinion’. If you want something useful to do over the holiday you could try to do some research to see if there is any evidence in support of water memory.

Feel free to look at your own resources, but you may want to check out some of these articles from the Skeptics society. Check out first the ‘about’ page to get an idea of where the Skeptics society is coming from. Then you may wish to look at

To get some balance check out the evidence for homeopathy from, and

Confused? Good! You might as well realise now that the path to enlightenment is not an easy one!

Hold everything!!

Hi folks

Apologies for this but I have been in contact with Ms Cavalli and she has requested that several of you be excused during the lesson tomorrow to help out with a CAS activity. If we still write the test tomorrow it means I would have to write separate HL and SL tests for the CAS participants. Consequently I have decided to move the test to


This means that the students who take SL Maths will be able to concentrate fully upon their Maths test on Friday!