Interesting read about telomeres (you will learn this in the later topics) for the layman

http://sg.news.yahoo.com/why-flatworms-may-hold-the-secret-to-immortality.html

"Key to a flatworm’s immortality lays in its telomeres – tiny sections of DNA that cap the ends of chromosomes, protecting them from damage and the loss of cell functions linked to ageing.

Each time a cell divides the protective telomere ‘cap’ gets shorter. When they get too short, the cell loses its ability to renew and divide. According to the study an immortal animal would expect cells to be able to maintain telomere length indefinitely so that they could continue to replicate. "

On the Straits Times

Read about 'Open Lectures' on the papers a few days back. It is a website with free online lectures catered for 'A' level students. As it is still in its infancy stage, there are not many lectures available yet. But you can still check it out, hopefully it is of use to you in time to come.

http://openlectures.sg/

Biological molecules tutorial (Protein recap): Response to questions posed in class today

Q1) Amino acids can be ionised in solution (i.e. Amino/NH2 group becomes NH3+, and Carboxyl/COOH group becomes COO-), hence they are soluble in water. So why can't the NH3+ and COO- groups form ionic bonds with each other?

A1) This is because the NH2 and COOH groups are involved in peptide bond formation. Hence ionic bonds in proteins can only be formed between the charged R groups.

Unionised form of amino acid

Ionised form of amino acid

Q2) FYI: What is the difference between haemoglobin and myoglobin?

A2) - Haemoglobin is found in red blood cells while myoglobin is found in muscle tissue.
- Haemoglobin consists of four polypeptide chains while myoglobin consists of one polypeptide chain.
- Haemoglobin transports oxygen while myoglobin stores oxygen (that is used during periods of oxygen deprivation).

Response to a blog query: Visual of a beta-pleated sheet

Beta-pleated sheet is made up of one polypeptide chain. The beta strands that make up the polypeptide chain can run in parallel or antiparallel directions.

Video animation on the levels of protein structure

Link to video shown in class:
http://www.youtube.com/watch?v=lijQ3a8yUYQ&list=FL-cFTJ8NxBjonnjuwSQgSsw&index=1&feature=plpp_video

Link to another video (not shown in class):
http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter2/animation__protein_denaturation.html

Hi!

Welcome to my blog! Please post any biology-related questions under comments (anywhere)! :)